# II. Physikalisches Institut BFachbereich Physik

## Publikationen – AG Morgenstern

### 2019

1. Pilot-scale fabrication and analysis of graphene-nanocomposite fibers Carbon 144, 351-361 (2019); doi:https://doi.org/10.1016/j.carbon.2018.12.042

Graphene/polymer composites can be spun into fibers with remarkable mechanical, thermal and electrical properties, but few studies have considered requirements for the pilot-scale production of such fibers using commercially available graphene nanoplatelets (GnP). To address this limitation, we fabricated melt-spun polyamide 6 (PA6) multifilament yarns in which 3% or 5% (w/w) GnP was incorporated into the PA6 matrix by melt compounding during the initial process step. We tested a range of melt-spinning process parameters and analyzed the properties of the resulting fibers in detail. We were able to fabricate yarns containing 24 single filaments at a maximum winding speed of 1800 m/min while applying a draw ratio of 2.5. The electrical conductivity of the as-spun yarns was in the 10 μS/m range, which is suitable for the production of anti-static textiles. Furthermore, the degree of crystallization declined as the GnP content increased, reducing the tenacity of the yarn but improving its elastic modulus, allowing the production of composite textiles. In conclusion, we confirmed that large amounts of graphene can be incorporated into PA6 polymers by melt spinning and that the resulting composite fibers are suitable for multiple downstream applications in the textile industry.

@article{WEISE2019351,
title = "Pilot-scale fabrication and analysis of graphene-nanocomposite fibers",
journal = "Carbon",
volume = "144",
pages = "351 - 361",
year = "2019",
issn = "0008-6223",
doi = "https://doi.org/10.1016/j.carbon.2018.12.042",
url = "http://www.sciencedirect.com/science/article/pii/S000862231831176X",
author = "Benjamin A. Weise and Konstantin G. Wirth and Lukas Völkel and Markus Morgenstern and Gunnar Seide",
abstract = "Graphene/polymer composites can be spun into fibers with remarkable mechanical, thermal and electrical properties, but few studies have considered requirements for the pilot-scale production of such fibers using commercially available graphene nanoplatelets (GnP). To address this limitation, we fabricated melt-spun polyamide 6 (PA6) multifilament yarns in which 3% or 5% (w/w) GnP was incorporated into the PA6 matrix by melt compounding during the initial process step. We tested a range of melt-spinning process parameters and analyzed the properties of the resulting fibers in detail. We were able to fabricate yarns containing 24 single filaments at a maximum winding speed of 1800 m/min while applying a draw ratio of 2.5. The electrical conductivity of the as-spun yarns was in the 10 μS/m range, which is suitable for the production of anti-static textiles. Furthermore, the degree of crystallization declined as the GnP content increased, reducing the tenacity of the yarn but improving its elastic modulus, allowing the production of composite textiles. In conclusion, we confirmed that large amounts of graphene can be incorporated into PA6 polymers by melt spinning and that the resulting composite fibers are suitable for multiple downstream applications in the textile industry."
}
2. Protection of one-dimensional Si chains embedded in Pt(111) and protected by a hexagonal boron-nitride monolayer Surface Science 685, 24-33 (2019); doi:https://doi.org/10.1016/j.susc.2019.01.013

Using scanning tunneling microscopy, we study the regime of submonolayer Si deposition on Pt(111) at 300 K. We find a novel network of one-dimensional chains embedded into the Pt surface. Even in ultrahigh vacuum, these chains disappear within a few hours in favor of clusters on top of the Pt surface. Exposing the chains to different gases reveals that CO effectively induces the lifting. However, the Si chains can be protected by a monolayer of hexagonal BN (h-BN) deposited prior to the Si deposition. Then, the chains survive even an exposure for ten min to air. Interestingly, the Si chains below the h-BN are rotated by 30∘ with respect to the ones on the bare Pt(111). This might be related to the anisotropic elastic modulus of the h-BN on top.

@article{ROSE201924,
author = {Rose, S. and Nemes-Incze, P. and Pratzer, M. and Caciuk, V.
and Atodiresei, N. and Morgenstern, M.},
title = {Protection of one-dimensional Si chains embedded in Pt(111) and protected by a hexagonal boron-nitride monolayer},
journal = {Surface Science},
volume = {685},
pages = {24 - 33},
year = {2019},
issn = {0039-6028},
doi = {https://doi.org/10.1016/j.susc.2019.01.013},
url = {http://www.sciencedirect.com/science/article/pii/S0039602818310343},
keywords = {Scanning tunneling microscopy, Pt-silicide, 1D systems, Dislocation lines, Hexagonal boron nitride protection},
abstract = {Using scanning tunneling microscopy, we study the regime of submonolayer Si deposition on Pt(111) at 300 K. We find a novel network of one-dimensional chains embedded into the Pt surface. Even in ultrahigh vacuum, these chains disappear within a few hours in favor of clusters on top of the Pt surface. Exposing the chains to different gases reveals that CO effectively induces the lifting. However, the Si chains can be protected by a monolayer of hexagonal BN (h-BN) deposited prior to the Si deposition. Then, the chains survive even an exposure for ten min to air. Interestingly, the Si chains below the h-BN are rotated by 30∘ with respect to the ones on the bare Pt(111). This might be related to the anisotropic elastic modulus of the h-BN on top.}
}

### 2018

1. Mapping the band structure of GeSbTe phase change alloys around the Fermi level Communications Physics 1, 5 (2018); doi:10.1038/s42005-018-0005-8

Phase change alloys are used for non-volatile random-access memories exploiting the conductivity contrast between amorphous and metastable, crystalline phase. However, this contrast has never been directly related to the electronic band structure. Here we employ photoelectron spectroscopy to map the relevant bands for metastable, epitaxial GeSbTe films. The constant energy surfaces of the valence band close to the Fermi level are hexagonal tubes with little dispersion perpendicular to the (111) surface. The electron density responsible for transport belongs to the tails of this bulk valence band, which is broadened by disorder, i.e., the Fermi level is 100 meV above the valence band maximum. This result is consistent with transport data of such films in terms of charge carrier density and scattering time. In addition, we find a state in the bulk band gap with linear dispersion, which might be of topological origin.

@ARTICLE{Kellner:844990,
author = {Kellner, J. and Bihlmayer, G. and Liebmann, M. and Otto, S.
and Pauly, C. and Boschker, J. E. and Bragaglia, V. and
Cecchi, S. and Wang, R. N. and Deringer, V. L. and Küppers,
P. and Bhaskar, P. and Golias, E. and Sánchez-Barriga, J.
and Dronskowski, R. and Fauster, T. and Rader, O. and
Calarco, R. and Morgenstern, M.},
title = {{M}apping the band structure of {G}e{S}b{T}e phase change
alloys around the {F}ermi level},
journal = {Communications Physics},
volume = {1},
number = {1},
issn = {2399-3650},
publisher = {Springer Nature},
reportid = {FZJ-2018-02325},
pages = {5},
year = {2018},
abstract = {Phase change alloys are used for non-volatile random-access
memories exploiting the conductivity contrast between
amorphous and metastable, crystalline phase. However, this
contrast has never been directly related to the electronic
band structure. Here we employ photoelectron spectroscopy to
map the relevant bands for metastable, epitaxial GeSbTe
films. The constant energy surfaces of the valence band
close to the Fermi level are hexagonal tubes with little
dispersion perpendicular to the (111) surface. The electron
density responsible for transport belongs to the tails of
this bulk valence band, which is broadened by disorder,
i.e., the Fermi level is 100 meV above the valence band
maximum. This result is consistent with transport data of
such films in terms of charge carrier density and scattering
time. In addition, we find a state in the bulk band gap with
linear dispersion, which might be of topological origin.},
cin = {PGI-1 / IAS-1 / JARA-FIT / JARA-HPC},
ddc = {530},
cid = {I:(DE-Juel1)PGI-1-20110106 / I:(DE-Juel1)IAS-1-20090406 /
$I:(DE-82)080009_20140620$ / $I:(DE-82)080012_20140620$},
pnm = {143 - Controlling Configuration-Based Phenomena (POF3-143)},
pid = {G:(DE-HGF)POF3-143},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000433471800005},
doi = {10.1038/s42005-018-0005-8},
url = {https://www.nature.com/articles/s42005-018-0005-8.pdf},
}
2. Mask aligner for ultrahigh vacuum with capacitive distance control Applied Physics Letters 112, 161602 (2018); doi:10.1063/1.5022462
@article{doi:10.1063/1.5022462,
author = {Priyamvada Bhaskar and Simon Mathioudakis and Tim Olschewski and Florian Muckel and Jan Raphael Bindel and Marco Pratzer and Marcus Liebmann and Markus Morgenstern},
title = {Mask aligner for ultrahigh vacuum with capacitive distance control},
journal = {Applied Physics Letters},
volume = {112},
number = {16},
pages = {161602},
year = {2018},
doi = {10.1063/1.5022462},
URL = {
https://doi.org/10.1063/1.5022462
},
eprint = {
https://doi.org/10.1063/1.5022462
}
}
3. Large tunable valley splitting in edge-free graphene quantum dots on boron nitride Nature Nanotechnology (2018); doi:10.1038/s41565-018-0080-8

Coherent manipulation of the binary degrees of freedom is at the heart of modern quantum technologies. Graphene offers two binary degrees: the electron spin and the valley. Efficient spin control has been demonstrated in many solid-state systems, whereas exploitation of the valley has only recently been started, albeit without control at the single-electron level. Here, we show that van der Waals stacking of graphene onto hexagonal boron nitride offers a natural platform for valley control. We use a graphene quantum dot induced by the tip of a scanning tunnelling microscope and demonstrate valley splitting that is tunable from −5 to +10 meV (including valley inversion) by sub-10-nm displacements of the quantum dot position. This boosts the range of controlled valley splitting by about one order of magnitude. The tunable inversion of spin and valley states should enable coherent superposition of these degrees of freedom as a first step towards graphene-based qubits.

@article{doi:10.1038/s41565-018-0080-8,
author = {Nils Freitag and Tobias Reisch and Larisa A. Chizhova and Péter Nemes Incze and Christian Holl and Colin R. Woods and Roman V. Gorbachev and Yang Cao and Andre K. Geim and Kostya S. Novosevov and Joachim Burgdörfer and Florian Libisch and Markus Morgenstern},
title = {Large tunable valley splitting in edge-free graphene quantum dots on boron nitride},
journal = {Nature Nanotechnology},year = {2018},
doi = {10.1038/s41565-018-0080-8},
URL = {https://www.nature.com/articles/s41565-018-0080-8
},
eprint = {
https://doi.org/10.1038/s41565-018-0080-8
}
,abstract = { Coherent manipulation of the binary degrees of freedom is at the heart of modern quantum technologies. Graphene offers two binary degrees: the electron spin and the valley. Efficient spin control has been demonstrated in many solid-state systems, whereas exploitation of the valley has only recently been started, albeit without control at the single-electron level. Here, we show that van der Waals stacking of graphene onto hexagonal boron nitride offers a natural platform for valley control. We use a graphene quantum dot induced by the tip of a scanning tunnelling microscope and demonstrate valley splitting that is tunable from −5 to +10 meV (including valley inversion) by sub-10-nm displacements of the quantum dot position. This boosts the range of controlled valley splitting by about one order of magnitude. The tunable inversion of spin and valley states should enable coherent superposition of these degrees of freedom as a first step towards graphene-based qubits. }
}

### 2017

1. Exploring the subsurface atomic structure of the epitaxially grown phase-change material Ge2Sb2Te5 Phys. Rev. B 96, 245408 (2017); doi:10.1103/PhysRevB.96.245408

Scanning tunneling microscopy (STM) and spectroscopy (STS) in combination with density functional theory (DFT) calculations are employed to study the surface and subsurface properties of the metastable phase of the phase-change material Ge2Sb2Te5 as grown by molecular beam epitaxy. The (111) surface is covered by an intact Te layer, which nevertheless permits the detection of the more disordered subsurface layer made of Ge and Sb atoms. Centrally, we find that the subsurface layer is significantly more ordered than expected for metastable Ge2Sb2Te5. First, we show that vacancies are nearly absent within the subsurface layer. Secondly, the potential fluctuation, tracked by the spatial variation of the valence band onset, is significantly less than expected for a random distribution of atoms and vacancies in the subsurface layer. The strength of the fluctuation is compatible with the potential distribution of charged acceptors without being influenced by other types of defects. Thirdly, DFT calculations predict a partially tetrahedral Ge bonding within a disordered subsurface layer, exhibiting a clear fingerprint in the local density of states as a peak close to the conduction band onset. This peak is absent in the STS data implying the absence of tetrahedral Ge, which is likely due to the missing vacancies required for structural relaxation around the shorter tetrahedral Ge bonds. Finally, isolated defect configurations with a low density of 10−4nm−2 are identified by comparison of STM and DFT data, which corroborates the significantly improved order in the epitaxial films driven by the buildup of vacancy layers.

@article{PhysRevB.96.245408,
title = {Exploring the subsurface atomic structure of the epitaxially grown phase-change material Ge2Sb2Te5},
author = {Kellner, J. and Bihlmayer, G. and Deringer, V. L. and Liebmann, M. and Pauly, C. and Giussani, A. and Boschker, J. E. and Calarco, R. and Dronskowski, R. and Morgenstern, M.},
journal = {Phys. Rev. B},
volume = {96},
issue = {24},
pages = {245408},
numpages = {11},
year = {2017},
month = {Dec},
publisher = {American Physical Society},
doi = {10.1103/PhysRevB.96.245408},
abstract = { Scanning tunneling microscopy (STM) and spectroscopy (STS) in combination with density functional theory (DFT) calculations are employed to study the surface and subsurface properties of the metastable phase of the phase-change material Ge2Sb2Te5 as grown by molecular beam epitaxy. The (111) surface is covered by an intact Te layer, which nevertheless permits the detection of the more disordered subsurface layer made of Ge and Sb atoms. Centrally, we find that the subsurface layer is significantly more ordered than expected for metastable Ge2Sb2Te5. First, we show that vacancies are nearly absent within the subsurface layer. Secondly, the potential fluctuation, tracked by the spatial variation of the valence band onset, is significantly less than expected for a random distribution of atoms and vacancies in the subsurface layer. The strength of the fluctuation is compatible with the potential distribution of charged acceptors without being influenced by other types of defects. Thirdly, DFT calculations predict a partially tetrahedral Ge bonding within a disordered subsurface layer, exhibiting a clear fingerprint in the local density of states as a peak close to the conduction band onset. This peak is absent in the STS data implying the absence of tetrahedral Ge, which is likely due to the missing vacancies required for structural relaxation around the shorter tetrahedral Ge bonds. Finally, isolated defect configurations with a low density of 10−4nm−2 are identified by comparison of STM and DFT data, which corroborates the significantly improved order in the epitaxial films driven by the buildup of vacancy layers. }
}
2. Bi1Te1 is a dual topological insulator Nature Communications 8, (2017);

New three-dimensional (3D) topological phases can emerge in superlattices containing constituents of known two-dimensional topologies. Here we demonstrate that stoichiometric Bi1Te1, which is a natural superlattice of alternating two Bi2Te3 quintuple layers and one Bi bilayer, is a dual 3D topological insulator where a weak topological insulator phase and topological crystalline insulator phase appear simultaneously. By density functional theory, we find indices (0;001) and a non-zero mirror Chern number. We have synthesized Bi1Te1 by molecular beam epitaxy and found evidence for its topological crystalline and weak topological character by spin- and angle-resolved photoemission spectroscopy. The dual topology opens the possibility to gap the differently protected metallic surface states on different surfaces independently by breaking the respective symmetries, for example, by magnetic field on one surface and by strain on another surface.

@article{eschbach2017bi1te1,
abstract = {New three-dimensional (3D) topological phases can emerge in superlattices containing constituents of known two-dimensional topologies. Here we demonstrate that stoichiometric Bi1Te1, which is a natural superlattice of alternating two Bi2Te3 quintuple layers and one Bi bilayer, is a dual 3D topological insulator where a weak topological insulator phase and topological crystalline insulator phase appear simultaneously. By density functional theory, we find indices (0;001) and a non-zero mirror Chern number. We have synthesized Bi1Te1 by molecular beam epitaxy and found evidence for its topological crystalline and weak topological character by spin- and angle-resolved photoemission spectroscopy. The dual topology opens the possibility to gap the differently protected metallic surface states on different surfaces independently by breaking the respective symmetries, for example, by magnetic field on one surface and by strain on another surface.},
author = {Eschbach, Markus and Lanius, Martin and Niu, Chengwang and Młyńczak, Ewa and Gospodarič, Pika and Kellner, Jens and Schüffelgen, Peter and Gehlmann, Mathias and Döring, Sven and Neumann, Elmar and Luysberg, Martina and Mussler, Gregor and Plucinski, Lukasz and Morgenstern, Markus and Grützmacher, Detlev and Bihlmayer, Gustav and Blügel, Stefan and Schneider, Claus M.},
interhash = {2d8bd4849d2c531324a99c54bdddcf25},
intrahash = {e829fe7ecb5cf1f3e0de6251886d4b73},
journal = {Nature Communications},
month = {April},
number = 14976,
title = {Bi1Te1 is a dual topological insulator},
url = {https://www.nature.com/articles/ncomms14976},
volume = 8,
year = 2017
}
3. Probing the Nodal Structure of Landau Level Wave Functions in Real Space Phys. Rev. Lett. 118, 16803 (2017); doi:10.1103/PhysRevLett.118.016803
@article{PhysRevLett.118.016803,
title = {Probing the Nodal Structure of Landau Level Wave Functions in Real Space},
author = {Bindel, J. R. and Ulrich, J. and Liebmann, M. and Morgenstern, M.},
journal = {Phys. Rev. Lett.},
volume = {118},
issue = {1},
pages = {016803},
numpages = {6},
year = {2017},
month = {Jan},
publisher = {American Physical Society},
doi = {10.1103/PhysRevLett.118.016803},
}
4. An ultrahigh-vacuum cryostat for simultaneous scanning tunneling microscopy and magneto-transport measurements down to 400 mK Review of Scientific Instruments 88, 123707 (2017); doi:10.1063/1.4999555
@article{doi:10.1063/1.4999555,
author = {Marcus Liebmann and Jan Raphael Bindel and Mike Pezzotta and Stefan Becker and Florian Muckel and Tjorven Johnsen and Christian Saunus and Christian R. Ast and Markus Morgenstern},
title = {An ultrahigh-vacuum cryostat for simultaneous scanning tunneling microscopy and magneto-transport measurements down to 400 mK},
journal = {Review of Scientific Instruments},
volume = {88},
number = {12},
pages = {123707},
year = {2017},
doi = {10.1063/1.4999555},
URL = {
https://doi.org/10.1063/1.4999555
},
eprint = {
https://doi.org/10.1063/1.4999555
}
}
5. Graphene Quantum Dots Probed by Scanning Tunneling Microscopy Annalen der Physik 529, 1700018 (2017); doi:10.1002/andp.201700018

Scanning tunneling spectroscopy results probing the electronic properties of graphene quantum dots are reviewed. After a short summary of the study of squared wave functions of graphene quantum dots on metal substrates, we firstly present data where the Landau level gaps caused by a perpendicular magnetic field are used to electrostatically confine electrons in monolayer graphene, which are probed by the Coulomb staircase revealing the consecutive charging of a quantum dot. It turns out that these quantum dots exhibit much more regular charging sequences than lithographically confined ones. Namely, the consistent grouping of charging peaks into quadruplets, both, in the electron and hole branch, portrays a regular orbital splitting of about 10meV. At low hole occupation numbers, the charging peaks are, partly, additionally grouped into doublets. The spatially varying energy separation of the doublets indicates a modulation of the valley splitting by the underlying BN substrate. We outline that this property might be used to eventually tune the valley splitting coherently. Afterwards, we describe graphene quantum dots with multiple contacts produced without lithographic resist, namely by local anodic oxidation. Such quantum dots target the goal to probe magnetotransport properties during the imaging of the corresponding wave functions by scanning tunneling spectroscopy.

@article {ANDP:ANDP201700018,
author = {Morgenstern, Markus and Freitag, Nils and Nent, Alexander and Nemes-Incze, Peter and Liebmann, Marcus},
title = {Graphene Quantum Dots Probed by Scanning Tunneling Microscopy},
journal = {Annalen der Physik},
volume = {529},
number = {11},
issn = {1521-3889},
url = {http://dx.doi.org/10.1002/andp.201700018},
doi = {10.1002/andp.201700018},
pages = {1700018--n/a},
keywords = {Graphene quantum dots, scanning tunneling microscopy, valley splitting, local anodic oxidation},
year = {2017},
pages = {1700018},
abstract = {Scanning tunneling spectroscopy results probing the electronic properties of graphene quantum dots are reviewed. After a short summary of the study of squared wave functions of graphene quantum dots on metal substrates, we firstly present data where the Landau level gaps caused by a perpendicular magnetic field are used to electrostatically confine electrons in monolayer graphene, which are probed by the Coulomb staircase revealing the consecutive charging of a quantum dot. It turns out that these quantum dots exhibit much more regular charging sequences than lithographically confined ones. Namely, the consistent grouping of charging peaks into quadruplets, both, in the electron and hole branch, portrays a regular orbital splitting of about 10meV. At low hole occupation numbers, the charging peaks are, partly, additionally grouped into doublets. The spatially varying energy separation of the doublets indicates a modulation of the valley splitting by the underlying BN substrate. We outline that this property might be used to eventually tune the valley splitting coherently. Afterwards, we describe graphene quantum dots with multiple contacts produced without lithographic resist, namely by local anodic oxidation. Such quantum dots target the goal to probe magnetotransport properties during the imaging of the corresponding wave functions by scanning tunneling spectroscopy.},
}
6. Tuning the Pseudospin Polarization of Graphene by a Pseudomagnetic Field Nano Letters 17, 2240-2245 (2017); doi:10.1021/acs.nanolett.6b04870

One of the intriguing characteristics of honeycomb lattices is the appearance of a pseudomagnetic field as a result of mechanical deformation. In the case of graphene, the Landau quantization resulting from this pseudomagnetic field has been measured using scanning tunneling microscopy. Here we show that a signature of the pseudomagnetic field is a local sublattice symmetry breaking observable as a redistribution of the local density of states. This can be interpreted as a polarization of graphene’s pseudospin due to a strain induced pseudomagnetic field, in analogy to the alignment of a real spin in a magnetic field. We reveal this sublattice symmetry breaking by tunably straining graphene using the tip of a scanning tunneling microscope. The tip locally lifts the graphene membrane from a SiO2 support, as visible by an increased slope of the I(z) curves. The amount of lifting is consistent with molecular dynamics calculations, which reveal a deformed graphene area under the tip in the shape of a Gaussian. The pseudomagnetic field induced by the deformation becomes visible as a sublattice symmetry breaking which scales with the lifting height of the strained deformation and therefore with the pseudomagnetic field strength. Its magnitude is quantitatively reproduced by analytic and tight-binding models, revealing fields of 1000 T. These results might be the starting point for an effective THz valley filter, as a basic element of valleytronics.

@article{doi:10.1021/acs.nanolett.6b04870,
abstract = {One of the intriguing characteristics of honeycomb lattices is the appearance of a pseudomagnetic field as a result of mechanical deformation. In the case of graphene, the Landau quantization resulting from this pseudomagnetic field has been measured using scanning tunneling microscopy. Here we show that a signature of the pseudomagnetic field is a local sublattice symmetry breaking observable as a redistribution of the local density of states. This can be interpreted as a polarization of graphene’s pseudospin due to a strain induced pseudomagnetic field, in analogy to the alignment of a real spin in a magnetic field. We reveal this sublattice symmetry breaking by tunably straining graphene using the tip of a scanning tunneling microscope. The tip locally lifts the graphene membrane from a SiO2 support, as visible by an increased slope of the I(z) curves. The amount of lifting is consistent with molecular dynamics calculations, which reveal a deformed graphene area under the tip in the shape of a Gaussian. The pseudomagnetic field induced by the deformation becomes visible as a sublattice symmetry breaking which scales with the lifting height of the strained deformation and therefore with the pseudomagnetic field strength. Its magnitude is quantitatively reproduced by analytic and tight-binding models, revealing fields of 1000 T. These results might be the starting point for an effective THz valley filter, as a basic element of valleytronics. },
author = {Georgi, Alexander and Nemes-Incze, Peter and Carrillo-Bastos, Ramon and Faria, Daiara and Viola Kusminskiy, Silvia and Zhai, Dawei and Schneider, Martin and Subramaniam, Dinesh and Mashoff, Torge and Freitag, Nils M. and Liebmann, Marcus and Pratzer, Marco and Wirtz, Ludger and Woods, Colin R. and Gorbachev, Roman V. and Cao, Yang and Novoselov, Kostya S. and Sandler, Nancy and Morgenstern, Markus},
doi = {10.1021/acs.nanolett.6b04870},
eprint = {http://dx.doi.org/10.1021/acs.nanolett.6b04870},
interhash = {42720c256c6587d86b91a8f5366bbd37},
intrahash = {9ce8e9b18dc0c569335486ed46bd5ecc},
journal = {Nano Letters},
note = {PMID: 28211276},
number = 4,
pages = {2240-2245},
title = {Tuning the Pseudospin Polarization of Graphene by a Pseudomagnetic Field},
url = {http://dx.doi.org/10.1021/acs.nanolett.6b04870},
volume = 17,
year = 2017
}
7. Chemical Tuning of Carrier Type and Concentration in a Homologous Series of Crystalline Chalcogenides Chemistry of Materials 29, 6749-6757 (2017); doi:10.1021/acs.chemmater.7b01595

Tellurium-based phase-change materials (PCMs) enable applications from optical and electronic data storage to thermoelectrics and plasmonics, which all demand precise control of electronic properties. These materials contain an unusually large number of vacancies: “stoichiometric” ones that stem from the chemical composition and “excess” vacancies that act like classical dopants. Here we show how both types of vacancies can be controlled independently in the solid solution Sn(Sb1–xBix)2Te4. We vary x in small steps over the entire compositional range and show that this has a profound effect on the material’s electronic nature: remarkably, we observe a change from p- to n-type conduction at x ≈ 0.7, solely controlled by composition. Our findings lead to a new compositionally (that is, chemically) tunable materials platform that enables precise control of electrical properties.

@article{doi:10.1021/acs.chemmater.7b01595,
author = {Schäfer, Tobias and Konze, Philipp M. and Huyeng, Jonas D. and Deringer, Volker L. and Lesieur, Thibault and Müller, Paul and Morgenstern, Markus and Dronskowski, Richard and Wuttig, Matthias},
title = {Chemical Tuning of Carrier Type and Concentration in a Homologous Series of Crystalline Chalcogenides},
journal = {Chemistry of Materials},
volume = {29},
number = {16},
pages = {6749-6757},
year = {2017},
doi = {10.1021/acs.chemmater.7b01595},
URL = {
http://dx.doi.org/10.1021/acs.chemmater.7b01595
},
eprint = {
http://dx.doi.org/10.1021/acs.chemmater.7b01595
}
,
abstract = { Tellurium-based phase-change materials (PCMs) enable applications from optical and electronic data storage to thermoelectrics and plasmonics, which all demand precise control of electronic properties. These materials contain an unusually large number of vacancies: “stoichiometric” ones that stem from the chemical composition and “excess” vacancies that act like classical dopants. Here we show how both types of vacancies can be controlled independently in the solid solution Sn(Sb1–xBix)2Te4. We vary x in small steps over the entire compositional range and show that this has a profound effect on the material’s electronic nature: remarkably, we observe a change from p- to n-type conduction at x ≈ 0.7, solely controlled by composition. Our findings lead to a new compositionally (that is, chemically) tunable materials platform that enables precise control of electrical properties. }
}

### 2016

1. Apparent rippling with honeycomb symmetry and tunable periodicity observed by scanning tunneling microscopy on suspended graphene Phys. Rev. B 94, 184302 (2016); doi:10.1103/PhysRevB.94.184302
@article{PhysRevB.94.184302,
title = {Apparent rippling with honeycomb symmetry and tunable periodicity observed by scanning tunneling microscopy on suspended graphene},
author = {Georgi, A. and Nemes-Incze, P. and Szafranek, B. and Neumaier, D. and Geringer, V. and Liebmann, M. and Morgenstern, M.},
journal = {Phys. Rev. B},
volume = {94},
issue = {18},
pages = {184302},
numpages = {10},
year = {2016},
month = {Nov},
publisher = {American Physical Society},
doi = {10.1103/PhysRevB.94.184302},
}
2. Spin mapping of surface and bulk Rashba states in ferroelectric $\ensuremath{\alpha}$-GeTe(111) films Phys. Rev. B 94, 201403 (2016); doi:10.1103/PhysRevB.94.201403
@article{PhysRevB.94.201403,
title = {Spin mapping of surface and bulk Rashba states in ferroelectric $\ensuremath{\alpha}$-GeTe(111) films},
author = {Elmers, H. J. and Wallauer, R. and Liebmann, M. and Kellner, J. and Morgenstern, M. and Wang, R. N. and Boschker, J. E. and Calarco, R. and S\'anchez-Barriga, J. and Rader, O. and Kutnyakhov, D. and Chernov, S. V. and Medjanik, K. and Tusche, C. and Ellguth, M. and Volfova, H. and Borek, St. and Braun, J. and Min\'ar, J. and Ebert, H. and Sch\"onhense, G.},
journal = {Phys. Rev. B},
volume = {94},
issue = {20},
pages = {201403},
numpages = {5},
year = {2016},
month = {Nov},
publisher = {American Physical Society},
doi = {10.1103/PhysRevB.94.201403},
}
3. Probing variations of the Rashba spin-orbit coupling at the nanometre scale Nat Phys 12, 920-925 (2016); doi:10.1038/nphys3774
@article{Bindel_2016,
author = {Bindel, Jan Raphael and Pezzotta, Mike and Ulrich, Jascha and Liebmann, Marcus and Sherman, Eugene Ya. and Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/2b8879439e91a08b3f326ac3c08cea9c8/institut2b},
doi = {10.1038/nphys3774},
interhash = {20259b0ee1987bb78bf6c1ccd5bde27f},
intrahash = {b8879439e91a08b3f326ac3c08cea9c8},
journal = {Nat Phys},
keywords = {morgenstern},
pages = {920-925},
month = may,
publisher = {Springer Nature},
timestamp = {2016-05-17T18:20:42.000+0200},
title = {Probing variations of the Rashba spin-orbit coupling at the nanometre scale},
url = {http://dx.doi.org/10.1038/nphys3774},
volume = 12,
year = 2016
}
4. Electrostatically Confined Monolayer Graphene Quantum Dots with Orbital and Valley Splittings Nano Letters 16, 5798-5805 (2016); doi:10.1021/acs.nanolett.6b02548

The electrostatic confinement of massless charge carriers is hampered by Klein tunneling. Circumventing this problem in graphene mainly relies on carving out nanostructures or applying electric displacement fields to open a band gap in bilayer graphene. So far, these approaches suffer from edge disorder or insufficiently controlled localization of electrons. Here we realize an alternative strategy in monolayer graphene, by combining a homogeneous magnetic field and electrostatic confinement. Using the tip of a scanning tunneling microscope, we induce a confining potential in the Landau gaps of bulk graphene without the need for physical edges. Gating the localized states toward the Fermi energy leads to regular charging sequences with more than 40 Coulomb peaks exhibiting typical addition energies of 7–20 meV. Orbital splittings of 4–10 meV and a valley splitting of about 3 meV for the first orbital state can be deduced. These experimental observations are quantitatively reproduced by tight binding calculations, which include the interactions of the graphene with the aligned hexagonal boron nitride substrate. The demonstrated confinement approach appears suitable to create quantum dots with well-defined wave function properties beyond the reach of traditional techniques.

@article{Freitag2016,
abstract = {The electrostatic confinement of massless charge carriers is hampered by Klein tunneling. Circumventing this problem in graphene mainly relies on carving out nanostructures or applying electric displacement fields to open a band gap in bilayer graphene. So far, these approaches suffer from edge disorder or insufficiently controlled localization of electrons. Here we realize an alternative strategy in monolayer graphene, by combining a homogeneous magnetic field and electrostatic confinement. Using the tip of a scanning tunneling microscope, we induce a confining potential in the Landau gaps of bulk graphene without the need for physical edges. Gating the localized states toward the Fermi energy leads to regular charging sequences with more than 40 Coulomb peaks exhibiting typical addition energies of 7–20 meV. Orbital splittings of 4–10 meV and a valley splitting of about 3 meV for the first orbital state can be deduced. These experimental observations are quantitatively reproduced by tight binding calculations, which include the interactions of the graphene with the aligned hexagonal boron nitride substrate. The demonstrated confinement approach appears suitable to create quantum dots with well-defined wave function properties beyond the reach of traditional techniques. },
author = {Freitag, Nils M. and Chizhova, Larisa A. and Nemes-Incze, Peter and Woods, Colin R. and Gorbachev, Roman V. and Cao, Yang and Geim, Andre K. and Novoselov, Kostya S. and Burgdörfer, Joachim and Libisch, Florian and Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/2c5ecec83f25bb8cc92c7c6d77bd8a5b2/institut2b},
doi = {10.1021/acs.nanolett.6b02548},
eprint = {http://dx.doi.org/10.1021/acs.nanolett.6b02548},
interhash = {217216f4599381e7879a6eef8dd5f5c0},
intrahash = {c5ecec83f25bb8cc92c7c6d77bd8a5b2},
journal = {Nano Letters},
keywords = {morgenstern},
note = {PMID: 27466881},
month = august,
number = 9,
pages = {5798-5805},
timestamp = {2016-08-09T13:39:08.000+0200},
title = {Electrostatically Confined Monolayer Graphene Quantum Dots with Orbital and Valley Splittings},
url = {http://dx.doi.org/10.1021/acs.nanolett.6b02548},
volume = 16,
year = 2016
}
5. Electronic Structure of the Dark Surface of the Weak Topological Insulator Bi14Rh3I9 ACS Nano 10, 3995-4003 (2016); doi:10.1021/acsnano.6b00841

Compound Bi14Rh3I9 consists of ionic stacks of intermetallic [(Bi4Rh)3I]2+ and insulating [Bi2I8]2– layers and has been identified to be a weak topological insulator. Scanning tunneling microscopy revealed the robust edge states at all step edges of the cationic layer as a topological fingerprint. However, these edge states are found 0.25 eV below the Fermi level, which is an obstacle for transport experiments. Here, we address this obstacle by comparing results of density functional slab calculations with scanning tunneling spectroscopy and angle-resolved photoemission spectroscopy. We show that the n-type doping of the intermetallic layer is intrinsically caused by the polar surface and is well-screened toward the bulk. In contrast, the anionic “spacer” layer shows a gap at the Fermi level, both on the surface and in the bulk; that is, it is not surface-doped due to iodine desorption. The well-screened surface dipole implies that a buried edge state, probably already below a single spacer layer, is located at the Fermi level. Consequently, a multilayer step covered by a spacer layer could provide access to the transport properties of the topological edge states. In addition, we find a lateral electronic modulation of the topologically nontrivial surface layer, which is traced back to the coupling with the underlying zigzag chain structure of the spacer layer.

@article{doi:10.1021/acsnano.6b00841,
abstract = { Compound Bi14Rh3I9 consists of ionic stacks of intermetallic [(Bi4Rh)3I]2+ and insulating [Bi2I8]2– layers and has been identified to be a weak topological insulator. Scanning tunneling microscopy revealed the robust edge states at all step edges of the cationic layer as a topological fingerprint. However, these edge states are found 0.25 eV below the Fermi level, which is an obstacle for transport experiments. Here, we address this obstacle by comparing results of density functional slab calculations with scanning tunneling spectroscopy and angle-resolved photoemission spectroscopy. We show that the n-type doping of the intermetallic layer is intrinsically caused by the polar surface and is well-screened toward the bulk. In contrast, the anionic “spacer” layer shows a gap at the Fermi level, both on the surface and in the bulk; that is, it is not surface-doped due to iodine desorption. The well-screened surface dipole implies that a buried edge state, probably already below a single spacer layer, is located at the Fermi level. Consequently, a multilayer step covered by a spacer layer could provide access to the transport properties of the topological edge states. In addition, we find a lateral electronic modulation of the topologically nontrivial surface layer, which is traced back to the coupling with the underlying zigzag chain structure of the spacer layer. },
author = {Pauly, Christian and Rasche, Bertold and Koepernik, Klaus and Richter, Manuel and Borisenko, Sergey and Liebmann, Marcus and Ruck, Michael and van den Brink, Jeroen and Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/2b9bc945d49dcdbc62c6fe7efc6d340d4/institut2b},
doi = {10.1021/acsnano.6b00841},
eprint = {http://dx.doi.org/10.1021/acsnano.6b00841},
interhash = {4426df61e3282336e92ac61dbc2190fd},
intrahash = {b9bc945d49dcdbc62c6fe7efc6d340d4},
journal = {ACS Nano},
keywords = {morgenstern},
note = {PMID: 26967061},
number = 4,
pages = {3995-4003},
timestamp = {2016-06-02T12:19:35.000+0200},
title = {Electronic Structure of the Dark Surface of the Weak Topological Insulator Bi14Rh3I9},
url = {/brokenurl# http://dx.doi.org/10.1021/acsnano.6b00841 },
volume = 10,
year = 2016
}
6. Giant Rashba-Type Spin Splitting in Ferroelectric GeTe(111) Advanced Materials 28, 560-565 (2016); doi:10.1002/adma.201503459
@article{ADMA:ADMA201503459,
author = {Liebmann, Marcus and Rinaldi, Christian and Di Sante, Domenico and Kellner, Jens and Pauly, Christian and Wang, Rui Ning and Boschker, Jos Emiel and Giussani, Alessandro and Bertoli, Stefano and Cantoni, Matteo and Baldrati, Lorenzo and Asa, Marco and Vobornik, Ivana and Panaccione, Giancarlo and Marchenko, Dmitry and Sánchez-Barriga, Jaime and Rader, Oliver and Calarco, Raffaella and Picozzi, Silvia and Bertacco, Riccardo and Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/268713471073e27725e5c16fc2781953a/institut2b},
interhash = {f7637e910d2d4b5eb6d9c30ff3711911},
intrahash = {68713471073e27725e5c16fc2781953a},
issn = {1521-4095},
keywords = {morgenstern},
number = 3,
pages = {560--565},
timestamp = {2016-04-22T10:47:48.000+0200},
title = {Giant Rashba-Type Spin Splitting in Ferroelectric GeTe(111)},
volume = 28,
year = 2016
}
7. Graphene quantum dots: wave function mapping by scanning tunneling spectroscopy and transport spectroscopy of quantum dots prepared by local anodic oxidation physica status solidi (RRL) – Rapid Research Letters 10, 24-38 (2016); doi:10.1002/pssr.201510164

Graphene quantum dots (GQDs) are considered as promising alternatives to quantum dots in III–V semiconductors, e.g., for the use as spin qubits. However, this potential has not been realized in experiments so far, calling for a more fundamental investigation of GQDs including a full control of the wave function properties during transport spectroscopy. Here, we review the recent success in mapping wave functions of GQDs by scanning tunneling microscopy (STM). We show that GQDs on Ir(111) are softly confined rendering the wave functions more regular. The wave function mapping is disturbed by a sp-type surface state from Ir(111), which can be improved by Au intercalation or adequate Fourier analysis. Edge states are absent on Ir(111), but reappear after intercalating Au and coupling the σ-bonds of the zig-zag edges to BN. Finally, we show how the goal of probing such wave functions during transport spectroscopy might be achieved. Therefore, we present transport spectroscopy of GQDs on SiO2 which are prepared in a STM compatible fashion.

@article{PSSR:PSSR201510164,
abstract = {Graphene quantum dots (GQDs) are considered as promising alternatives to quantum dots in III–V semiconductors, e.g., for the use as spin qubits. However, this potential has not been realized in experiments so far, calling for a more fundamental investigation of GQDs including a full control of the wave function properties during transport spectroscopy. Here, we review the recent success in mapping wave functions of GQDs by scanning tunneling microscopy (STM). We show that GQDs on Ir(111) are softly confined rendering the wave functions more regular. The wave function mapping is disturbed by a sp-type surface state from Ir(111), which can be improved by Au intercalation or adequate Fourier analysis. Edge states are absent on Ir(111), but reappear after intercalating Au and coupling the σ-bonds of the zig-zag edges to BN. Finally, we show how the goal of probing such wave functions during transport spectroscopy might be achieved. Therefore, we present transport spectroscopy of GQDs on SiO2 which are prepared in a STM compatible fashion.},
author = {Morgenstern, Markus and Freitag, Nils and Vaid, Aviral and Pratzer, Marco and Liebmann, Marcus},
biburl = {http://www.bibsonomy.org/bibtex/2d45cb4ae34b547d5a76f537a4e50f202/institut2b},
doi = {10.1002/pssr.201510164},
interhash = {6de77937d1c91f0a70ca246c9ed0d7ef},
intrahash = {d45cb4ae34b547d5a76f537a4e50f202},
issn = {1862-6270},
journal = {physica status solidi (RRL) – Rapid Research Letters},
keywords = {morgenstern},
number = 1,
pages = {24--38},
publisher = {WILEY-VCH Verlag Berlin GmbH},
timestamp = {2016-02-11T18:20:56.000+0100},
title = {Graphene quantum dots: wave function mapping by scanning tunneling spectroscopy and transport spectroscopy of quantum dots prepared by local anodic oxidation},
url = {http://dx.doi.org/10.1002/pssr.201510164},
volume = 10,
year = 2016
}

### 2015

1. Realization of a vertical topological p-n junction in epitaxial Sb2Te3/Bi2Te3 heterostructures Nat Commun 6, (2015);

Three-dimensional (3D) topological insulators are a new state of quantum matter, which exhibits both a bulk band structure with an insulating energy gap as well as metallic spin-polarized Dirac fermion states when interfaced with a topologically trivial material. There have been various attempts to tune the Dirac point to a desired energetic position for exploring its unusual quantum properties. Here we show a direct experimental proof by angle-resolved photoemission of the realization of a vertical topological p-n junction made of a heterostructure of two different binary 3D TI materials Bi2Te3 and Sb2Te3 epitaxially grown on Si(111). We demonstrate that the chemical potential is tunable by about 200[thinsp]meV when decreasing the upper Sb2Te3 layer thickness from 25 to 6 quintuple layers without applying any external bias. These results make it realistic to observe the topological exciton condensate and pave the way for exploring other exotic quantum phenomena in the near future.

@article{eschbach2015realization,
abstract = {Three-dimensional (3D) topological insulators are a new state of quantum matter, which exhibits both a bulk band structure with an insulating energy gap as well as metallic spin-polarized Dirac fermion states when interfaced with a topologically trivial material. There have been various attempts to tune the Dirac point to a desired energetic position for exploring its unusual quantum properties. Here we show a direct experimental proof by angle-resolved photoemission of the realization of a vertical topological p-n junction made of a heterostructure of two different binary 3D TI materials Bi2Te3 and Sb2Te3 epitaxially grown on Si(111). We demonstrate that the chemical potential is tunable by about 200[thinsp]meV when decreasing the upper Sb2Te3 layer thickness from 25 to 6 quintuple layers without applying any external bias. These results make it realistic to observe the topological exciton condensate and pave the way for exploring other exotic quantum phenomena in the near future.},
author = {Eschbach, Markus and Mlynczak, Ewa and Kellner, Jens and Kampmeier, Jorn and Lanius, Martin and Neumann, Elmar and Weyrich, Christian and Gehlmann, Mathias and Gospodaric, Pika and Doring, Sven and Mussler, Gregor and Demarina, Nataliya and Luysberg, Martina and Bihlmayer, Gustav and Schapers, Thomas and Plucinski, Lukasz and Blugel, Stefan and Morgenstern, Markus and Schneider, Claus M. and Grutzmacher, Detlev},
description = {Realization of a vertical topological p-n junction in epitaxial Sb2Te3/Bi2Te3 heterostructures : Nature Communications : Nature Publishing Group},
interhash = {3e03bd9867b61efafe54a9eb926c25ed},
journal = {Nat Commun},
keywords = {morgenstern},
month = nov,
timestamp = {2015-11-23T16:32:28.000+0100},
title = {Realization of a vertical topological p-n junction in epitaxial Sb2Te3/Bi2Te3 heterostructures},
url = {http://dx.doi.org/10.1038/ncomms9816},
volume = 6,
year = 2015
}
2. Spatially resolved Landau level spectroscopy of the topological Dirac cone of bulk-type Sb2Te3(0001): Potential fluctuations and quasiparticle lifetime Phys. Rev. B 92, 85140 (2015); doi:10.1103/PhysRevB.92.085140
@article{PhysRevB.92.085140,
title = {Spatially resolved Landau level spectroscopy of the topological Dirac cone of bulk-type Sb2Te3(0001): Potential fluctuations and quasiparticle lifetime},
author = {Pauly, C. and Saunus, C. and Liebmann, M. and Morgenstern, M.},
journal = {Phys. Rev. B},
volume = {92},
issue = {8},
pages = {085140},
numpages = {8},
year = {2015},
month = {Aug},
publisher = {American Physical Society},
doi = {10.1103/PhysRevB.92.085140},
}
3. Subnanometre-wide electron channels protected by topology Nat Phys 11, 338-343 (2015); doi:10.1038/nphys3264
@article{pauly2015subnanometrewide,
author = {Pauly, Christian and Rasche, Bertold and Koepernik, Klaus and Liebmann, Marcus and Pratzer, Marco and Richter, Manuel and Kellner, Jens and Eschbach, Markus and Kaufmann, Bernhard and Plucinski, Lukasz and Schneider, Claus M. and Ruck, Michael and van den Brink, Jeroen and Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/2c651d215ea047932c8e18942667172bb/institut2b},
description = {Subnanometre-wide electron channels protected by topology : Nature Physics : Nature Publishing Group},
doi = {10.1038/nphys3264},
interhash = {f553c2b6230289ac44ac4ebe385ec823},
intrahash = {c651d215ea047932c8e18942667172bb},
issn = {17452481},
journal = {Nat Phys},
keywords = {morgenstern},
month = mar,
number = 4,
pages = {338 - 343},
publisher = {Nature Publishing Group},
timestamp = {2015-03-16T23:58:42.000+0100},
title = {Subnanometre-wide electron channels protected by topology},
url = {http://dx.doi.org/10.1038/nphys3264},
volume = {11},
year = 2015
}
4. Tuning the Dirac point to the Fermi level in the ternary topological insulator (Bi1−xSbx)2Te3 Applied Physics Letters 107, 251603 (2015); doi:http://dx.doi.org/10.1063/1.4938394

In order to stabilize Majorana excitations within vortices of proximity induced topological superconductors, it is mandatory that the Dirac point matches the Fermi level rather exactly, such that the conventionally confined states within the vortex are well separated from the Majorana-type excitation. Here, we show by angle resolved photoelectron spectroscopy that (Bi1−xSbx)2Te3 thin films with x = 0.94 prepared by molecular beam epitaxy and transferred in ultrahigh vacuum from the molecular beam epitaxy system to the photoemission setup match this condition. The Dirac point is within 10 meV around the Fermi level, and we do not observe any bulk bands intersecting the Fermi level.

@article{:/content/aip/journal/apl/107/25/10.1063/1.4938394,
abstract = {In order to stabilize Majorana excitations within vortices of proximity induced topological superconductors, it is mandatory that the Dirac point matches the Fermi level rather exactly, such that the conventionally confined states within the vortex are well separated from the Majorana-type excitation. Here, we show by angle resolved photoelectron spectroscopy that (Bi1−xSbx)2Te3 thin films with x = 0.94 prepared by molecular beam epitaxy and transferred in ultrahigh vacuum from the molecular beam epitaxy system to the photoemission setup match this condition. The Dirac point is within 10 meV around the Fermi level, and we do not observe any bulk bands intersecting the Fermi level.},
author = {Kellner, Jens and Eschbach, Markus and Kampmeier, Jörn and Lanius, Martin and Młyńczak, Ewa and Mussler, Gregor and Holländer, Bernhard and Plucinski, Lukasz and Liebmann, Marcus and Grützmacher, Detlev and Schneider, Claus M. and Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/2da2ea066dcab2597fd80f3a81c344e36/institut2b},
doi = {http://dx.doi.org/10.1063/1.4938394},
eid = {251603},
interhash = {f15e3c872251b7254fcbf60090a16f8f},
intrahash = {da2ea066dcab2597fd80f3a81c344e36},
journal = {Applied Physics Letters},
keywords = {morgenstern},
number = 25,
pages = 251603,
timestamp = {2016-03-31T14:46:38.000+0200},
title = {Tuning the Dirac point to the Fermi level in the ternary topological insulator (Bi1−xSbx)2Te3},
url = {http://scitation.aip.org/content/aip/journal/apl/107/25/10.1063/1.4938394},
volume = 107,
year = 2015
}

### 2014

1. Preferential antiferromagnetic coupling of vacancies in graphene on ${\mathrm{SiO}}_{2}$: Electron spin resonance and scanning tunneling spectroscopy Phys. Rev. B 90, 125449 (2014); doi:10.1103/PhysRevB.90.125449
@article{PhysRevB.90.125449,
author = {Just, S. and Zimmermann, S. and Kataev, V. and B\"uchner, B. and Pratzer, M. and Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/2f3607da821cb854d5b54ef005fda8e76/institut2b},
description = {Phys. Rev. B 90, 125449 (2014) - Preferential antiferromagnetic coupling of vacancies in graphene on ${\mathrm{SiO}}_{2}$: Electron spin resonance and scanning tunneling spectroscopy},
doi = {10.1103/PhysRevB.90.125449},
interhash = {0efba1ed73afc55c689d99b9d9d9a64b},
intrahash = {f3607da821cb854d5b54ef005fda8e76},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = sep,
number = 12,
numpages = {9},
eid = {125449},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:17:40.000+0100},
title = {Preferential antiferromagnetic coupling of vacancies in graphene on ${\mathrm{SiO}}_{2}$: Electron spin resonance and scanning tunneling spectroscopy},
volume = 90,
year = 2014
}
2. Diffractive-wave guiding of surface electrons on Au(111) by the herringbone reconstruction potential Phys. Rev. B 90, 035442 (2014); doi:10.1103/PhysRevB.90.035442
@article{PhysRevB.90.035442,
author = {Libisch, F. and Geringer, V. and Subramaniam, D. and Burgd\"orfer, J. and Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/2a655454bf8b41d8cca597bfddcd98a50/institut2b},
description = {Phys. Rev. B 90, 035442 (2014) - Diffractive-wave guiding of surface electrons on Au(111) by the herringbone reconstruction potential},
doi = {10.1103/PhysRevB.90.035442},
interhash = {b2ef7dbaa0b01d56f4a43fc5c63277e9},
intrahash = {a655454bf8b41d8cca597bfddcd98a50},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = jul,
number = 3,
numpages = {9},
eid = {035442},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:18:11.000+0100},
title = {Diffractive-wave guiding of surface electrons on Au(111) by the herringbone reconstruction potential},
volume = 90,
year = 2014
}
3. Analyzing multiple encounter as a possible origin of electron spin resonance signals in scanning tunneling microscopy on Si(111) featuring C and O defects Surface Science 623, 47-54 (2014); doi:10.1016/j.susc.2013.12.009

Abstract The Si(111)7 × 7 surface exposed to 0.1 L of \{O2\} and the carbonized Si(111) surface are investigated by electron spin resonance scanning tunneling microscopy (ESR-STM) using frequency sweeps and magnetic field sweeps. Only after oxidizing the clean Si(111)7 × 7 or by using the carbonized Si(111), spatially averaged ESR-STM spectra exhibit several peaks and dips around the frequencies corresponding to g = 2. The energy difference between these features is close to the known hyperfine splitting of A ? 9 MHz for vacancies in SiC interacting with next-nearest neighbor 29Si. Such spectra with peaks and dips can be qualitatively reproduced by introducing a primary encounter of the lead electrons with the localized spin correlating the two spins which afterwards evolve in different local hyperfine fields, thus, developing a relative spin angle prior to tunneling.

@article{Manassen201447,
abstract = {Abstract The Si(111)7 × 7 surface exposed to 0.1 L of \{O2\} and the carbonized Si(111) surface are investigated by electron spin resonance scanning tunneling microscopy (ESR-STM) using frequency sweeps and magnetic field sweeps. Only after oxidizing the clean Si(111)7 × 7 or by using the carbonized Si(111), spatially averaged ESR-STM spectra exhibit several peaks and dips around the frequencies corresponding to g = 2. The energy difference between these features is close to the known hyperfine splitting of A ? 9 MHz for vacancies in SiC interacting with next-nearest neighbor 29Si. Such spectra with peaks and dips can be qualitatively reproduced by introducing a primary encounter of the lead electrons with the localized spin correlating the two spins which afterwards evolve in different local hyperfine fields, thus, developing a relative spin angle prior to tunneling. },
author = {Manassen, Y. and Averbukh, M. and Morgenstern, M.},
description = {Analyzing multiple encounter as a possible origin of electron spin resonance signals in scanning tunneling microscopy on Si(111) featuring C and O defects},
doi = {10.1016/j.susc.2013.12.009},
interhash = {ac02c847c9e95a1b03ab2aeb3e9c6e62},
issn = {0039-6028},
journal = {Surface Science },
keywords = {morgenstern},
number = 0,
pages = {47 - 54},
timestamp = {2015-03-17T00:16:09.000+0100},
title = {Analyzing multiple encounter as a possible origin of electron spin resonance signals in scanning tunneling microscopy on Si(111) featuring C and O defects },
url = {http://www.sciencedirect.com/science/article/pii/S0039602813003695},
volume = 623,
year = 2014
}

### 2013

1. Electronic and Magnetic Properties of Zigzag Graphene Nanoribbons on the (111) Surface of Cu, Ag, and Au Phys. Rev. Lett. 110, 216804 (2013); doi:10.1103/PhysRevLett.110.216804
@article{PhysRevLett.110.216804,
author = {Li, Yan and Zhang, Wei and Morgenstern, Markus and Mazzarello, Riccardo},
biburl = {http://www.bibsonomy.org/bibtex/2f4619dc30d6096bb5f76dfe226ffee9e/institut2b},
description = {Phys. Rev. Lett. 110, 216804 (2013) - Electronic and Magnetic Properties of Zigzag Graphene Nanoribbons on the (111) Surface of Cu, Ag, and Au},
doi = {10.1103/PhysRevLett.110.216804},
interhash = {e8c3ce0e3f71e84d18252158ed986949},
intrahash = {f4619dc30d6096bb5f76dfe226ffee9e},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = may,
number = 21,
numpages = {5},
eid = {216804},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:19:19.000+0100},
title = {Electronic and Magnetic Properties of Zigzag Graphene Nanoribbons on the (111) Surface of Cu, Ag, and Au},
volume = 110,
year = 2013
}
2. Evidence for topological band inversion of the phase change material Ge2Sb2Te5 Applied Physics Letters 103, 243109 (2013); doi:10.1063/1.4847715

We present an angle-resolved photoemission study of a ternary phase change material, namely Ge 2Sb2Te5, epitaxially grown on Si(111) in the metastable cubic phase. The observed upper bulk valence band shows a minimum at being 0.3eV below the Fermi level E F and a circular Fermi contour around with a dispersing diameter of 0.27–0.36Å-1. This is in agreement with density functional theory calculations of the Petrov stacking sequence in the cubic phase which exhibits a topological surface state. The topologically trivial cubic Kooi-De Hosson stacking shows a valence band maximum at G in line with all previous calculations of the hexagonal stable phase exhibiting the valence band maximum at G for a trivial topological invariant and away from G for non-trivial . Scanning tunneling spectroscopy exhibits a band gap of 0.4eV around E F. G ¯ G ¯ Z 2 ? 0 ? 0

@article{:/content/aip/journal/apl/103/24/10.1063/1.4847715,
abstract = {We present an angle-resolved photoemission study of a ternary phase change material, namely Ge 2Sb2Te5, epitaxially grown on Si(111) in the metastable cubic phase. The observed upper bulk valence band shows a minimum at being 0.3eV below the Fermi level E F and a circular Fermi contour around with a dispersing diameter of 0.27–0.36Å-1. This is in agreement with density functional theory calculations of the Petrov stacking sequence in the cubic phase which exhibits a topological surface state. The topologically trivial cubic Kooi-De Hosson stacking shows a valence band maximum at G in line with all previous calculations of the hexagonal stable phase exhibiting the valence band maximum at G for a trivial topological invariant and away from G for non-trivial . Scanning tunneling spectroscopy exhibits a band gap of 0.4eV around E F. G ¯ G ¯ Z 2 ? 0 ? 0},
author = {Pauly, Christian and Liebmann, Marcus and Giussani, Alessandro and Kellner, Jens and Just, Sven and Sánchez-Barriga, Jaime and Rienks, Emile and Rader, Oliver and Calarco, Raffaella and Bihlmayer, Gustav and Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/2d5a7a3ea1c605083e0793291a38bfb37/institut2b},
description = {Evidence for topological band inversion of the phase change material Ge2Sb2Te5},
doi = {10.1063/1.4847715},
eid = {243109},
interhash = {ac6942bc95b9c12011653d942e38ea41},
intrahash = {d5a7a3ea1c605083e0793291a38bfb37},
journal = {Applied Physics Letters},
keywords = {morgenstern},
number = 24,
timestamp = {2015-03-17T00:18:27.000+0100},
title = {Evidence for topological band inversion of the phase change material Ge2Sb2Te5},
url = {http://scitation.aip.org/content/aip/journal/apl/103/24/10.1063/1.4847715},
volume = 103,
year = 2013
}
3. Absence of Edge States in Covalently Bonded Zigzag Edges of Graphene on Ir(111) Advanced Materials 25, 1967-1972 (2013); doi:10.1002/adma.201204539
@article{ADMA:ADMA201204539,
author = {Li, Yan and Subramaniam, Dinesh and Atodiresei, Nicolae and Lazic, Predrag and Caciuc, Vasile and Pauly, Christian and Georgi, Alexander and Busse, Carsten and Liebmann, Marcus and Blügel, Stefan and Pratzer, Marco and Morgenstern, Markus and Mazzarello, Riccardo},
biburl = {http://www.bibsonomy.org/bibtex/29004e5c20dee0a9f84a02680fa614004/institut2b},
description = {Absence of Edge States in Covalently Bonded Zigzag Edges of Graphene on Ir(111) - Li - 2013 - Advanced Materials - Wiley Online Library},
interhash = {2b17f5b3893a63e14b412712d9e47305},
intrahash = {9004e5c20dee0a9f84a02680fa614004},
issn = {1521-4095},
keywords = {morgenstern},
number = 14,
pages = {1967--1972},
publisher = {WILEY-VCH Verlag},
timestamp = {2015-03-17T00:19:48.000+0100},
title = {Absence of Edge States in Covalently Bonded Zigzag Edges of Graphene on Ir(111)},
volume = 25,
year = 2013
}
4. Networks of \ABA\ and \ABC\ stacked graphene on mica observed by scanning tunneling microscopy Surface Science 610, 53-58 (2013); doi:10.1016/j.susc.2013.01.005

Abstract Graphene flakes are prepared on freshly cleaved mica by exfoliation and studied by scanning tunneling microscopy in ultra high vacuum. On few-layer graphene, a triangular network of partial dislocations separating \{ABC\} stacked and \{ABA\} stacked graphene was found similar to the networks occasionally visible on freshly cleaved HOPG. We found differences in the electronic structure of \{ABC\} and \{ABA\} stacked areas by scanning tunneling spectroscopy, i.e., a pronounced peak at 0.25 eV above the Fermi level exclusively in the \{ABA\} areas, which is shown to be responsible for the different apparent heights observed in \{STM\} images.

@article{Hattendorf201353,
abstract = {Abstract Graphene flakes are prepared on freshly cleaved mica by exfoliation and studied by scanning tunneling microscopy in ultra high vacuum. On few-layer graphene, a triangular network of partial dislocations separating \{ABC\} stacked and \{ABA\} stacked graphene was found similar to the networks occasionally visible on freshly cleaved HOPG. We found differences in the electronic structure of \{ABC\} and \{ABA\} stacked areas by scanning tunneling spectroscopy, i.e., a pronounced peak at 0.25 eV above the Fermi level exclusively in the \{ABA\} areas, which is shown to be responsible for the different apparent heights observed in \{STM\} images. },
author = {Hattendorf, S. and Georgi, A. and Liebmann, M. and Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/2d65d39bc7613fa8f10f72c6dd9864b02/institut2b},
description = {Networks of ABA and ABC stacked graphene on mica observed by scanning tunneling microscopy},
doi = {10.1016/j.susc.2013.01.005},
interhash = {c4a132a1aa60bbf957a693290da99bd7},
intrahash = {d65d39bc7613fa8f10f72c6dd9864b02},
issn = {0039-6028},
journal = {Surface Science },
keywords = {morgenstern},
number = 0,
pages = {53 - 58},
timestamp = {2015-03-17T00:19:54.000+0100},
title = {Networks of \{ABA\} and \{ABC\} stacked graphene on mica observed by scanning tunneling microscopy },
url = {http://www.sciencedirect.com/science/article/pii/S0039602813000101},
volume = 610,
year = 2013
}
5. Versatile scanning tunneling microscopy with 120ps time resolution Applied Physics Letters 102, 051601 (2013); doi:10.1063/1.4790180

We describe a fully ultra-high vacuum compatible scanning tunneling microscope (STM) optimized for radio-frequency signals. It includes in-situ exchangeable tips adapted to high frequency cabling and a standard sample holder, which offer access to the whole range of samples typically investigated by STM. We demonstrate a time resolution of 120ps using the nonlinear I(V)-characteristic of the surface of highly oriented pyrolithic graphite. We provide atomically resolved images in pulse mode related to a spatially varying nonlinearity of the local density of states of the sample, thus, demonstrating the possible spatial resolution of the instrument in pulse mode. Analysis of the noise reveals that changes in the tunneling junction of 50pA are dynamically detectable at 120ps time resolution.

@article{:/content/aip/journal/apl/102/5/10.1063/1.4790180,
abstract = {We describe a fully ultra-high vacuum compatible scanning tunneling microscope (STM) optimized for radio-frequency signals. It includes in-situ exchangeable tips adapted to high frequency cabling and a standard sample holder, which offer access to the whole range of samples typically investigated by STM. We demonstrate a time resolution of 120ps using the nonlinear I(V)-characteristic of the surface of highly oriented pyrolithic graphite. We provide atomically resolved images in pulse mode related to a spatially varying nonlinearity of the local density of states of the sample, thus, demonstrating the possible spatial resolution of the instrument in pulse mode. Analysis of the noise reveals that changes in the tunneling junction of 50pA are dynamically detectable at 120ps time resolution.},
author = {Saunus, Christian and Raphael Bindel, Jan and Pratzer, Marco and Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/2b1288f492f765ae277a07f424394a19a/institut2b},
description = {Versatile scanning tunneling microscopy with 120ps time resolution},
doi = {10.1063/1.4790180},
eid = {051601},
interhash = {42855c0861bdeef9a0cc9beb945cc8f4},
intrahash = {b1288f492f765ae277a07f424394a19a},
journal = {Applied Physics Letters},
keywords = {morgenstern},
number = 5,
timestamp = {2015-03-17T00:20:01.000+0100},
title = {Versatile scanning tunneling microscopy with 120ps time resolution},
url = {http://scitation.aip.org/content/aip/journal/apl/102/5/10.1063/1.4790180},
volume = 102,
year = 2013
}

### 2012

1. Probing two topological surface bands of Sb${}_{2}$Te${}_{3}$ by spin-polarized photoemission spectroscopy Phys. Rev. B 86, 235106 (2012); doi:10.1103/PhysRevB.86.235106
@article{PhysRevB.86.235106,
author = {Pauly, C. and Bihlmayer, G. and Liebmann, M. and Grob, M. and Georgi, A. and Subramaniam, D. and Scholz, M. R. and S\'anchez-Barriga, J. and Varykhalov, A. and Bl\"ugel, S. and Rader, O. and Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/22a7554bd80f303246c6a3600b597ce7a/institut2b},
description = {Phys. Rev. B 86, 235106 (2012) - Probing two topological surface bands of Sb${}_{2}$Te${}_{3}$ by spin-polarized photoemission spectroscopy},
doi = {10.1103/PhysRevB.86.235106},
interhash = {694812f932b8bf608750202e2c398745},
intrahash = {2a7554bd80f303246c6a3600b597ce7a},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = dec,
number = 23,
numpages = {8},
eid = {235106},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:21:14.000+0100},
title = {Probing two topological surface bands of Sb${}_{2}$Te${}_{3}$ by spin-polarized photoemission spectroscopy},
volume = 86,
year = 2012
}
2. Robust Nodal Structure of Landau Level Wave Functions Revealed by Fourier Transform Scanning Tunneling Spectroscopy Phys. Rev. Lett. 109, 116805 (2012); doi:10.1103/PhysRevLett.109.116805
@article{PhysRevLett.109.116805,
author = {Hashimoto, K. and Champel, T. and Florens, S. and Sohrmann, C. and Wiebe, J. and Hirayama, Y. and R\"omer, R. A. and Wiesendanger, R. and Morgenstern, M.},
description = {Phys. Rev. Lett. 109, 116805 (2012) - Robust Nodal Structure of Landau Level Wave Functions Revealed by Fourier Transform Scanning Tunneling Spectroscopy},
doi = {10.1103/PhysRevLett.109.116805},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = sep,
number = 11,
numpages = {5},
eid = {116805},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:21:44.000+0100},
title = {Robust Nodal Structure of Landau Level Wave Functions Revealed by Fourier Transform Scanning Tunneling Spectroscopy},
volume = 109,
year = 2012
}
3. Catalytic growth of N-doped MgO on Mo(001) Phys. Rev. B 86, 075455 (2012); doi:10.1103/PhysRevB.86.075455
@article{PhysRevB.86.075455,
author = {Grob, Martin and Pratzer, Marco and Morgenstern, Markus and Ležaic, Marjana},
biburl = {http://www.bibsonomy.org/bibtex/2f0509696130ea0250c92145a3c1e90c8/institut2b},
description = {Phys. Rev. B 86, 075455 (2012) - Catalytic growth of N-doped MgO on Mo(001)},
doi = {10.1103/PhysRevB.86.075455},
interhash = {97b6dc6640deb59875c08116899345b6},
intrahash = {f0509696130ea0250c92145a3c1e90c8},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = aug,
number = 7,
numpages = {5},
eid = {075455},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:21:19.000+0100},
title = {Catalytic growth of N-doped MgO on Mo(001)},
volume = 86,
year = 2012
}
4. Wave-Function Mapping of Graphene Quantum Dots with Soft Confinement Phys. Rev. Lett. 108, 046801 (2012); doi:10.1103/PhysRevLett.108.046801
@article{PhysRevLett.108.046801,
author = {Subramaniam, D. and Libisch, F. and Li, Y. and Pauly, C. and Geringer, V. and Reiter, R. and Mashoff, T. and Liebmann, M. and Burgd\"orfer, J. and Busse, C. and Michely, T. and Mazzarello, R. and Pratzer, M. and Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/23a34fe872aa1160ec4eb8b2b80fbbf67/institut2b},
description = {Phys. Rev. Lett. 108, 046801 (2012) - Wave-Function Mapping of Graphene Quantum Dots with Soft Confinement},
doi = {10.1103/PhysRevLett.108.046801},
interhash = {e0222ddc637ffeab382950974f136942},
intrahash = {3a34fe872aa1160ec4eb8b2b80fbbf67},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = jan,
number = 4,
numpages = {5},
eid = {046801},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:21:07.000+0100},
title = {Wave-Function Mapping of Graphene Quantum Dots with Soft Confinement},
volume = 108,
year = 2012
}
5. Monitoring structural influences on quantum transport in InAs nanowires Applied Physics Letters 101, 062104 (2012); doi:10.1063/1.4742326

A sample design that allows for quantum transport and transmission electron microscopy(TEM) on individual suspended nanostructures is used to investigate moderately n-type dopedInAsnanowires (NWs). The nanowires were grown by metal organic vapor phase epitaxy. Universal conductance fluctuations in the nanowires are investigated at temperatures down to 0.35K. These fluctuations show two different temperature dependences. The very same nanowire segments investigated in transport are subsequently analyzed by TEM revealing crystal phase mixing. However, we find no correspondence between the atomic structure of the wires and the temperature dependences of the conductance fluctuations.

@article{:/content/aip/journal/apl/101/6/10.1063/1.4742326,
abstract = {A sample design that allows for quantum transport and transmission electron microscopy(TEM) on individual suspended nanostructures is used to investigate moderately n-type dopedInAsnanowires (NWs). The nanowires were grown by metal organic vapor phase epitaxy. Universal conductance fluctuations in the nanowires are investigated at temperatures down to 0.35K. These fluctuations show two different temperature dependences. The very same nanowire segments investigated in transport are subsequently analyzed by TEM revealing crystal phase mixing. However, we find no correspondence between the atomic structure of the wires and the temperature dependences of the conductance fluctuations.},
author = {Frielinghaus, Robert and Flöhr, Kilian and Sladek, Kamil and Weirich, Thomas E. and Trellenkamp, Stefan and Hardtdegen, Hilde and Schäpers, Thomas and Schneider, Claus M. and Meyer, Carola},
description = {Monitoring structural influences on quantum transport in InAs nanowires},
doi = {10.1063/1.4742326},
eid = {062104},
interhash = {6ca3c6cd5e43a09862a939040148da40},
journal = {Applied Physics Letters},
keywords = {morgenstern},
number = 6,
timestamp = {2015-03-17T00:21:29.000+0100},
title = {Monitoring structural influences on quantum transport in InAs nanowires},
url = {http://scitation.aip.org/content/aip/journal/apl/101/6/10.1063/1.4742326},
volume = 101,
year = 2012
}
6. Scanning tunneling microscopy of two-dimensional semiconductors: Spin properties and disorder Physica E: Low-dimensional Systems and Nanostructures 44, 1795-1814 (2012); doi:10.1016/j.physe.2012.06.006

The interrelation between spin and charge in semiconductors leads to interesting effects, e.g., the Rashba-type spin–orbit splitting or the exchange enhancement. These properties are proposed to be used in applications such as spin transistors or spin qubits. Probing them on the local scale with the ultimate spatial resolution of the scanning tunneling microscope addresses their susceptibility to disorder directly. Here we review the results obtained on two-dimensional electron systems (2DESs) in semiconductors. We describe the preparation and characterization of an adequate 2DES which can be probed by scanning tunneling microscopy. It is shown how the electron density and the disorder within the 2DES can be tuned and measured. The observed local density of states of weakly and strongly disordered systems is discussed in detail. It is shown that the weakly disordered 2DES exhibits quantum Hall effect in magnetic field. The corresponding local density of states across a quantum Hall transition is mapped showing the development from localized states to extended states and back to localized states in real space. Decoupling the 2DES from screening electrons of the bulk of the III–V semiconductor leads to a measurable exchange enhancement of up to 0.7 meV which depends on the local spin polarization of the 2DES. At stronger confinement potential, i.e. larger doping, the Rashba spin splitting with a as large as 7×10-11 eV m is observed as a beating in the density of states in magnetic field. The Rashba spin splitting varies with position by about ±50% being largest at potential hills.

@article{Morgenstern20121795,
abstract = {The interrelation between spin and charge in semiconductors leads to interesting effects, e.g., the Rashba-type spin–orbit splitting or the exchange enhancement. These properties are proposed to be used in applications such as spin transistors or spin qubits. Probing them on the local scale with the ultimate spatial resolution of the scanning tunneling microscope addresses their susceptibility to disorder directly. Here we review the results obtained on two-dimensional electron systems (2DESs) in semiconductors. We describe the preparation and characterization of an adequate 2DES which can be probed by scanning tunneling microscopy. It is shown how the electron density and the disorder within the 2DES can be tuned and measured. The observed local density of states of weakly and strongly disordered systems is discussed in detail. It is shown that the weakly disordered 2DES exhibits quantum Hall effect in magnetic field. The corresponding local density of states across a quantum Hall transition is mapped showing the development from localized states to extended states and back to localized states in real space. Decoupling the 2DES from screening electrons of the bulk of the III–V semiconductor leads to a measurable exchange enhancement of up to 0.7 meV which depends on the local spin polarization of the 2DES. At stronger confinement potential, i.e. larger doping, the Rashba spin splitting with a as large as 7×10-11 eV m is observed as a beating in the density of states in magnetic field. The Rashba spin splitting varies with position by about ±50% being largest at potential hills. },
author = {Morgenstern, M. and Georgi, A. and Straßer, C. and Ast, C.R. and Becker, S. and Liebmann, M.},
biburl = {http://www.bibsonomy.org/bibtex/26cc8457f0d4cff5caee6e5be330d0b3d/institut2b},
description = {Scanning tunneling microscopy of two-dimensional semiconductors: Spin properties and disorder},
doi = {10.1016/j.physe.2012.06.006},
interhash = {8bbdcfbaa672ba5b864d6a1e91da262a},
intrahash = {6cc8457f0d4cff5caee6e5be330d0b3d},
issn = {1386-9477},
journal = {Physica E: Low-dimensional Systems and Nanostructures },
keywords = {morgenstern},
number = 9,
pages = {1795 - 1814},
timestamp = {2015-03-17T00:21:40.000+0100},
title = {Scanning tunneling microscopy of two-dimensional semiconductors: Spin properties and disorder },
url = {http://www.sciencedirect.com/science/article/pii/S1386947712002263},
volume = 44,
year = 2012
}
7. H 2 O on Pt(111): structure and stability of the first wetting layer Journal of Physics: Condensed Matter 24, 124103 (2012);

We study the structure and stability of the first water layer on Pt(111) by variable-temperature scanning tunneling microscopy. We find that a high Pt step edge density considerably increases the long-range order of the equilibrium ##IMG## [http://ej.iop.org/images/0953-8984/24/12/124103/cm405363ieqn1.gif] {$\sqrt{37}\times \sqrt{37}\mathrm{R25.3}$} °- and ##IMG## [http://ej.iop.org/images/0953-8984/24/12/124103/cm405363ieqn2.gif] {$\sqrt{39}\times \sqrt{39}\mathrm{R16.1}$} °-superstructures, presumably due to the capability of step edges to trap residual adsorbates from the surface. Passivating the step edges with CO or preparing a flat metal surface leads to the formation of disordered structures, which still show the same structural elements as the ordered ones. Coadsorption of Xe and CO proves that the water layer covers the metal surface completely. Moreover, we determine the two-dimensional crystal structure of Xe on top of the chemisorbed water layer which exhibits an Xe–Xe distance close to the one in bulk Xe and a rotation angle of 90° between the close-packed directions of Xe and the close-packed directions of the underlying water layer. CO is shown to replace H 2 O on the Pt(111) surface as has been deduced previously. In addition, we demonstrate that tunneling of electrons into the antibonding state or from the bonding state of H 2 O leads to dissociation of the molecules and a corresponding reordering of the adlayer into a ##IMG## [http://ej.iop.org/images/0953-8984/24/12/124103/cm405363ieqn3.gif] {$\sqrt{3}\times \sqrt{3}\mathrm{R30}$} °-structure. Finally, a so far not understood restructuring of the adlayer by an increased tunneling current has been observed.

@article{0953-8984-24-12-124103,
abstract = {We study the structure and stability of the first water layer on Pt(111) by variable-temperature scanning tunneling microscopy. We find that a high Pt step edge density considerably increases the long-range order of the equilibrium ##IMG## [http://ej.iop.org/images/0953-8984/24/12/124103/cm405363ieqn1.gif] {$\sqrt{37}\times \sqrt{37}\mathrm{R25.3}$} °- and ##IMG## [http://ej.iop.org/images/0953-8984/24/12/124103/cm405363ieqn2.gif] {$\sqrt{39}\times \sqrt{39}\mathrm{R16.1}$} °-superstructures, presumably due to the capability of step edges to trap residual adsorbates from the surface. Passivating the step edges with CO or preparing a flat metal surface leads to the formation of disordered structures, which still show the same structural elements as the ordered ones. Coadsorption of Xe and CO proves that the water layer covers the metal surface completely. Moreover, we determine the two-dimensional crystal structure of Xe on top of the chemisorbed water layer which exhibits an Xe–Xe distance close to the one in bulk Xe and a rotation angle of 90° between the close-packed directions of Xe and the close-packed directions of the underlying water layer. CO is shown to replace H 2 O on the Pt(111) surface as has been deduced previously. In addition, we demonstrate that tunneling of electrons into the antibonding state or from the bonding state of H 2 O leads to dissociation of the molecules and a corresponding reordering of the adlayer into a ##IMG## [http://ej.iop.org/images/0953-8984/24/12/124103/cm405363ieqn3.gif] {$\sqrt{3}\times \sqrt{3}\mathrm{R30}$} °-structure. Finally, a so far not understood restructuring of the adlayer by an increased tunneling current has been observed.},
author = {Standop, Sebastian and Morgenstern, Markus and Michely, Thomas and Busse, Carsten},
biburl = {http://www.bibsonomy.org/bibtex/2c31148c225bbebd4355b4b33147b0208/institut2b},
description = {H2O on Pt(111): structure and stability of the first wetting layer - Abstract - Journal of Physics: Condensed Matter - IOPscience},
interhash = {12ea44d658e2873859687f49b670ff99},
intrahash = {c31148c225bbebd4355b4b33147b0208},
journal = {Journal of Physics: Condensed Matter},
keywords = {morgenstern},
number = 12,
eid = {124103},
timestamp = {2015-03-17T00:21:47.000+0100},
title = {H 2 O on Pt(111): structure and stability of the first wetting layer},
url = {http://stacks.iop.org/0953-8984/24/i=12/a=124103},
volume = 24,
year = 2012
}
8. Scanning tunneling microscopy with InAs nanowire tips Applied Physics Letters 101, 243101 (2012); doi:10.1063/1.4769450

Indium arsenide nanowiresgrown by selective-area vapor phase epitaxy are used as tips for scanning tunneling microscopy(STM). The STM tips are realized by positioning the wires manually on the corner of a double cleaved gallium arsenide wafer with sub-µm precision and contacting them lithographically, which is fully compatible with further integrated circuitry on the GaAs wafer. STM images show a z noise of 2pm and a lateral stability of, at least, 0.5nm on a Au(111) surface.I(z) spectroscopy reveals an exponential decay indicating tunneling through vacuum. Subsequent electron microscopy images of the tip demonstrate that the wires are barely modified during the STM imaging.

@article{:/content/aip/journal/apl/101/24/10.1063/1.4769450,
abstract = {Indium arsenide nanowiresgrown by selective-area vapor phase epitaxy are used as tips for scanning tunneling microscopy(STM). The STM tips are realized by positioning the wires manually on the corner of a double cleaved gallium arsenide wafer with sub-µm precision and contacting them lithographically, which is fully compatible with further integrated circuitry on the GaAs wafer. STM images show a z noise of 2pm and a lateral stability of, at least, 0.5nm on a Au(111) surface.I(z) spectroscopy reveals an exponential decay indicating tunneling through vacuum. Subsequent electron microscopy images of the tip demonstrate that the wires are barely modified during the STM imaging.},
author = {Flöhr, Kilian and Sladek, Kamil and Yusuf Günel, H. and Ion Lepsa, Mihail and Hardtdegen, Hilde and Liebmann, Marcus and Schäpers, Thomas and Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/22b66d8eb206fb55826beff8015eff31e/institut2b},
description = {Scanning tunneling microscopy with InAs nanowire tips},
doi = {10.1063/1.4769450},
eid = {243101},
interhash = {f73d9d45cc3735c1550b890c1b68cc68},
intrahash = {2b66d8eb206fb55826beff8015eff31e},
journal = {Applied Physics Letters},
keywords = {morgenstern},
number = 24,
timestamp = {2015-03-17T00:21:24.000+0100},
title = {Scanning tunneling microscopy with InAs nanowire tips},
url = {http://scitation.aip.org/content/aip/journal/apl/101/24/10.1063/1.4769450},
volume = 101,
year = 2012
}

### 2011

1. Probing Electron-Electron Interaction in Quantum Hall Systems with Scanning Tunneling Spectroscopy Phys. Rev. Lett. 106, 156805 (2011); doi:10.1103/PhysRevLett.106.156805
@article{PhysRevLett.106.156805,
author = {Becker, S. and Karrasch, C. and Mashoff, T. and Pratzer, M. and Liebmann, M. and Meden, V. and Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/2d108d9f2f45962afccb8863869e5280c/institut2b},
description = {Phys. Rev. Lett. 106, 156805 (2011) - Probing Electron-Electron Interaction in Quantum Hall Systems with Scanning Tunneling Spectroscopy},
doi = {10.1103/PhysRevLett.106.156805},
intrahash = {d108d9f2f45962afccb8863869e5280c},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = apr,
number = 15,
numpages = {4},
eid = {156805},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:22:48.000+0100},
title = {Probing Electron-Electron Interaction in Quantum Hall Systems with Scanning Tunneling Spectroscopy},
volume = 106,
year = 2011
}
2. Scanning tunneling microscopy and spectroscopy of graphene on insulating substrates physica status solidi (b) 248, 2423-2434 (2011); doi:10.1002/pssb.201147312

Graphene is a truly two-dimensional (2D) material with exceptional electronic, mechanical, and optical properties. As such, it consists of surface only and can be probed by the well-developed surface science techniques such as, e.g., scanning tunneling microscopy (STM). This method bridges the gap between the surface science community and the electronic device community and might lead to novel combined approaches. Here, I review some of the STM and scanning tunneling spectroscopy (STS) experiments on monolayer graphene samples. I will concentrate on graphene samples deposited on insulating substrates, since these are related to graphene device concepts. In particular, I will discuss the morphology of graphene on SiO2 and other emerging substrates, some nanomechanical manipulation experiments using STM, and spectroscopic results. The latter can map the disorder potentials as well as the interaction of the electrons with the disorder, which is most pronounced in the quantum Hall regime.Three-dimensional representation of a STM image of graphene; the atomic resolution is displayed as color code, while the rippling is shown in three dimensions (courtesy of M. Pratzer, RWTH Aachen).

@article{PSSB:PSSB201147312,
abstract = {Graphene is a truly two-dimensional (2D) material with exceptional electronic, mechanical, and optical properties. As such, it consists of surface only and can be probed by the well-developed surface science techniques such as, e.g., scanning tunneling microscopy (STM). This method bridges the gap between the surface science community and the electronic device community and might lead to novel combined approaches. Here, I review some of the STM and scanning tunneling spectroscopy (STS) experiments on monolayer graphene samples. I will concentrate on graphene samples deposited on insulating substrates, since these are related to graphene device concepts. In particular, I will discuss the morphology of graphene on SiO2 and other emerging substrates, some nanomechanical manipulation experiments using STM, and spectroscopic results. The latter can map the disorder potentials as well as the interaction of the electrons with the disorder, which is most pronounced in the quantum Hall regime.Three-dimensional representation of a STM image of graphene; the atomic resolution is displayed as color code, while the rippling is shown in three dimensions (courtesy of M. Pratzer, RWTH Aachen).},
author = {Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/22ced71a42e1d774db15fb4f300393419/institut2b},
description = {Scanning tunneling microscopy and spectroscopy of graphene on insulating substrates - Morgenstern - 2011 - physica status solidi (b) - Wiley Online Library},
doi = {10.1002/pssb.201147312},
interhash = {da10f7f18ee0dc089e7307f0b03bdcf6},
intrahash = {2ced71a42e1d774db15fb4f300393419},
issn = {1521-3951},
journal = {physica status solidi (b)},
keywords = {morgenstern},
number = 11,
pages = {2423--2434},
publisher = {WILEY-VCH Verlag},
timestamp = {2015-03-17T00:24:09.000+0100},
title = {Scanning tunneling microscopy and spectroscopy of graphene on insulating substrates},
url = {http://dx.doi.org/10.1002/pssb.201147312},
volume = 248,
year = 2011
}
3. Manipulating InAs nanowires with submicrometer precision Review of Scientific Instruments 82, 113705 (2011); doi:10.1063/1.3657135

InAsnanowires are grown epitaxially by catalyst-free metal organic vapor phase epitaxy and are subsequently positioned with a lateral accuracy of less than 1 µm using simple adhesion forces between the nanowires and an indium tip. The technique, requiring only an optical microscope, is used to place individual nanowires onto the corner of a cleaved-edge wafer as well as across predefined holes in Si3N4 membranes. The precision of the method is limited by the stability of the micromanipulators and the precision of the optical microscope.

@article{:/content/aip/journal/rsi/82/11/10.1063/1.3657135,
abstract = {InAsnanowires are grown epitaxially by catalyst-free metal organic vapor phase epitaxy and are subsequently positioned with a lateral accuracy of less than 1 µm using simple adhesion forces between the nanowires and an indium tip. The technique, requiring only an optical microscope, is used to place individual nanowires onto the corner of a cleaved-edge wafer as well as across predefined holes in Si3N4 membranes. The precision of the method is limited by the stability of the micromanipulators and the precision of the optical microscope.},
author = {Flöhr, Kilian and Liebmann, Marcus and Sladek, Kamil and Günel, H. Yusuf and Frielinghaus, Robert and Haas, Fabian and Meyer, Carola and Hardtdegen, Hilde and Schäpers, Thomas and Grützmacher, Detlev and Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/21772892de8682a3b33d1f46543586b59/institut2b},
description = {Manipulating InAs nanowires with submicrometer precision},
doi = {10.1063/1.3657135},
eid = {113705},
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journal = {Review of Scientific Instruments},
keywords = {morgenstern},
number = 11,
timestamp = {2015-03-17T00:24:12.000+0100},
title = {Manipulating InAs nanowires with submicrometer precision},
url = {http://scitation.aip.org/content/aip/journal/rsi/82/11/10.1063/1.3657135},
volume = 82,
year = 2011
}
4. Jenseits des Gleichgewichts Physik in unserer Zeit 42, 168-175 (2011); doi:10.1002/piuz.201101271

Das Rastertunnelmikroskop bildet mit seiner Spitze Oberflächen und Nanostrukturen mit atomarer Präzision ab. Traditionell klärt es die Gleichgewichtseigenschaften von Atomen, Elektronen und magnetischen Dipolen auf. Inzwischen kann es auch dynamische Nichtgleichgewichts-Eigenschaften mit atomarer Präzision vermessen. Drei Beispiele demonstrieren dies. Im ersten Beispiel werden mit der inelastischen Tunnelspektroskopie die Energien und Lebensdauern von magnetischen Anregungen, Magnonen, vermessen. Im zweiten Beispiel bringt eine oszillierende Tunnelspannung eine Nanotrommel aus nur 800 Kohlenstoffatomen zum Schwingen. Im dritten Beispiel wird das Umklappen des magnetischen Dipols eines Atoms mit Nanosekunden-Präzision verfolgt. Dabei zeigt sich, dass der Dipol seine magnetische Ausrichtung nicht durch Drehen, sondern durch Tunneln ändert.

@article{PIUZ:PIUZ201101271,
abstract = {Das Rastertunnelmikroskop bildet mit seiner Spitze Oberflächen und Nanostrukturen mit atomarer Präzision ab. Traditionell klärt es die Gleichgewichtseigenschaften von Atomen, Elektronen und magnetischen Dipolen auf. Inzwischen kann es auch dynamische Nichtgleichgewichts-Eigenschaften mit atomarer Präzision vermessen. Drei Beispiele demonstrieren dies. Im ersten Beispiel werden mit der inelastischen Tunnelspektroskopie die Energien und Lebensdauern von magnetischen Anregungen, Magnonen, vermessen. Im zweiten Beispiel bringt eine oszillierende Tunnelspannung eine Nanotrommel aus nur 800 Kohlenstoffatomen zum Schwingen. Im dritten Beispiel wird das Umklappen des magnetischen Dipols eines Atoms mit Nanosekunden-Präzision verfolgt. Dabei zeigt sich, dass der Dipol seine magnetische Ausrichtung nicht durch Drehen, sondern durch Tunneln ändert.},
author = {Loth, Sebastian and Morgenstern, Markus and Wulfhekel, Wulf},
biburl = {http://www.bibsonomy.org/bibtex/224c45fbd6f50eff85d7a0ee1ac514ea3/institut2b},
description = {Jenseits des Gleichgewichts - Loth - 2011 - Physik in unserer Zeit - Wiley Online Library},
doi = {10.1002/piuz.201101271},
interhash = {de18e33e4676657cea5095b5725d20c8},
intrahash = {24c45fbd6f50eff85d7a0ee1ac514ea3},
issn = {1521-3943},
journal = {Physik in unserer Zeit},
keywords = {morgenstern},
number = 4,
pages = {168--175},
publisher = {WILEY-VCH Verlag},
timestamp = {2015-03-17T00:24:15.000+0100},
title = {Jenseits des Gleichgewichts},
url = {http://dx.doi.org/10.1002/piuz.201101271},
volume = 42,
year = 2011
}
5. Real-space mapping of a disordered two-dimensional electron system in the quantum Hall regime Journal of Physics: Conference Series 334, 012008 (2011);

By using scanning tunnelling spectroscopy, we study the influence of potential disorder on an adsorbate-induced two-dimensional electron system in the integer quantum Hall regime. The real-space imaged local density of states exhibits transition from localized drift states encircling the potential minima to another type of localized drift states encircling the potential maxima. While the former states show regular round shapes, the latter have irregular-shaped patterns. This difference is induced by different sources for the potential minima and maxima, i.e., substrate donors and an inhomogeneous distribution of the adsorbates, respectively.

@article{1742-6596-334-1-012008,
abstract = {By using scanning tunnelling spectroscopy, we study the influence of potential disorder on an adsorbate-induced two-dimensional electron system in the integer quantum Hall regime. The real-space imaged local density of states exhibits transition from localized drift states encircling the potential minima to another type of localized drift states encircling the potential maxima. While the former states show regular round shapes, the latter have irregular-shaped patterns. This difference is induced by different sources for the potential minima and maxima, i.e., substrate donors and an inhomogeneous distribution of the adsorbates, respectively.},
author = {Hashimoto, K and Wiebe, J and Inaoka, T and Hirayama, Y and Wiesendanger, R and Morgenstern, M},
biburl = {http://www.bibsonomy.org/bibtex/258858a94cfd827bd5e884ff75e49325f/institut2b},
description = {Real-space mapping of a disordered two-dimensional electron system in the quantum Hall regime - Abstract - Journal of Physics: Conference Series - IOPscience},
interhash = {38d2ccddb7aceef83147d0fd8f2ff2a0},
intrahash = {58858a94cfd827bd5e884ff75e49325f},
journal = {Journal of Physics: Conference Series},
keywords = {morgenstern},
number = 1,
eid = {012008},
timestamp = {2015-03-17T00:24:19.000+0100},
title = {Real-space mapping of a disordered two-dimensional electron system in the quantum Hall regime},
url = {http://stacks.iop.org/1742-6596/334/i=1/a=012008},
volume = 334,
year = 2011
}
6. M. Markus, M. Jorge, M. Thomas, and C. George. The Ice Bilayer on Pt(111): Nucleation, Structure and Melting. 2011. doi:10.1524/zpch.1997.198.Part_1_2.043
@misc{markus2011bilayer,
author = {Markus, Morgenstern and Jorge, Müller and Thomas, Michely and George, Comsa},
biburl = {http://www.bibsonomy.org/bibtex/27f473bd042cdc36aa47ed52f9ec1fb2d/institut2b},
booktitle = {Zeitschrift für Physikalische Chemie},
description = {The Ice Bilayer on Pt(111): Nucleation, Structure and Melting : Zeitschrift für Physikalische Chemie},
doi = {10.1524/zpch.1997.198.Part_1_2.043},
interhash = {9b7c2f73979634f0b8f42eb7a717f2e1},
intrahash = {7f473bd042cdc36aa47ed52f9ec1fb2d},
keywords = {morgenstern},
pages = {43--},
timestamp = {2015-03-17T01:20:25.000+0100},
title = {The Ice Bilayer on Pt(111): Nucleation, Structure and Melting},
url = {/brokenurl#//www.degruyter.com/view/j/zpch.1997.198.issue-part_1_2/zpch.1997.198.part_1_2.043/zpch.1997.198.part_1_2.043.xml},
volume = 198,
year = 2011
}

### 2010

1. Molecular structure of the ${\text{H}}_{2}\text{O}$ wetting layer on Pt(111) Phys. Rev. B 82, 161412 (2010); doi:10.1103/PhysRevB.82.161412
@article{PhysRevB.82.161412,
author = {Standop, Sebastian and Redinger, Alex and Morgenstern, Markus and Michely, Thomas and Busse, Carsten},
biburl = {http://www.bibsonomy.org/bibtex/24ff222c9a46111eff229d8d45a8be9ba/institut2b},
description = {Phys. Rev. B 82, 161412(R) (2010) - Molecular structure of the ${\text{H}}_{2}\text{O}$ wetting layer on Pt(111)},
doi = {10.1103/PhysRevB.82.161412},
interhash = {cdd99105412837180ffe69c224deb93e},
intrahash = {4ff222c9a46111eff229d8d45a8be9ba},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = oct,
number = 16,
numpages = {4},
eid = {161412},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:24:40.000+0100},
title = {Molecular structure of the ${\text{H}}_{2}\text{O}$ wetting layer on Pt(111)},
volume = 82,
year = 2010
}
2. Scanning tunneling spectroscopy of a dilute two-dimensional electron system exhibiting Rashba spin splitting Phys. Rev. B 81, 155308 (2010); doi:10.1103/PhysRevB.81.155308
@article{PhysRevB.81.155308,
author = {Becker, S. and Liebmann, M. and Mashoff, T. and Pratzer, M. and Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/2f3a0256dbddd57bb15c7641e312e9492/institut2b},
description = {Phys. Rev. B 81, 155308 (2010) - Scanning tunneling spectroscopy of a dilute two-dimensional electron system exhibiting Rashba spin splitting},
doi = {10.1103/PhysRevB.81.155308},
interhash = {5d9c04766928861fcd1e9c460e696f6a},
intrahash = {f3a0256dbddd57bb15c7641e312e9492},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = apr,
number = 15,
numpages = {9},
eid = {155308},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:24:34.000+0100},
title = {Scanning tunneling spectroscopy of a dilute two-dimensional electron system exhibiting Rashba spin splitting},
volume = 81,
year = 2010
}
3. Gundlach oscillations and Coulomb blockade of Co nanoislands on MgO/Mo(100) investigated by scanning tunneling spectroscopy at 300 K Phys. Rev. B 81, 125446 (2010); doi:10.1103/PhysRevB.81.125446
@article{PhysRevB.81.125446,
author = {Pauly, C. and Grob, M. and Pezzotta, M. and Pratzer, M. and Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/24ccd72bcd289e4e962e67f5b3d42f63d/institut2b},
description = {Phys. Rev. B 81, 125446 (2010) - Gundlach oscillations and Coulomb blockade of Co nanoislands on MgO/Mo(100) investigated by scanning tunneling spectroscopy at 300 K},
doi = {10.1103/PhysRevB.81.125446},
interhash = {7417aa3916d645343ce31719275fd5f5},
intrahash = {4ccd72bcd289e4e962e67f5b3d42f63d},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = mar,
number = 12,
numpages = {7},
eid = {125446},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:24:29.000+0100},
title = {Gundlach oscillations and Coulomb blockade of Co nanoislands on MgO/Mo(100) investigated by scanning tunneling spectroscopy at 300 K},
volume = 81,
year = 2010
}
4. Bistability and Oscillatory Motion of Natural Nanomembranes Appearing within Monolayer Graphene on Silicon Dioxide Nano Letters 10, 461-465 (2010); doi:10.1021/nl903133w

The truly two-dimensional material graphene is an ideal candidate for nanoelectromechanics due to its large strength and mobility. Here we show that graphene flakes provide natural nanomembranes of diameter down to 3 nm within its intrinsic rippling. The membranes can be lifted either reversibly or hysteretically by the tip of a scanning tunneling microscope. The clamped-membrane model including van-der-Waals and dielectric forces explains the results quantitatively. AC-fields oscillate the membranes, which might lead to a completely novel approach to controlled quantized oscillations or single atom mass detection.

@article{doi:10.1021/nl903133w,
abstract = { The truly two-dimensional material graphene is an ideal candidate for nanoelectromechanics due to its large strength and mobility. Here we show that graphene flakes provide natural nanomembranes of diameter down to 3 nm within its intrinsic rippling. The membranes can be lifted either reversibly or hysteretically by the tip of a scanning tunneling microscope. The clamped-membrane model including van-der-Waals and dielectric forces explains the results quantitatively. AC-fields oscillate the membranes, which might lead to a completely novel approach to controlled quantized oscillations or single atom mass detection. },
author = {Mashoff, T. and Pratzer, M. and Geringer, V. and Echtermeyer, T. J. and Lemme, M. C. and Liebmann, M. and Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/271d1547a95810e6c7debf537d10c31ef/institut2b},
description = {Bistability and Oscillatory Motion of Natural Nanomembranes Appearing within Monolayer Graphene on Silicon Dioxide - Nano Letters (ACS Publications)},
doi = {10.1021/nl903133w},
eprint = {http://dx.doi.org/10.1021/nl903133w},
interhash = {5e251da00049e1b52e896414ee422cd7},
intrahash = {71d1547a95810e6c7debf537d10c31ef},
journal = {Nano Letters},
keywords = {morgenstern},
note = {PMID: 20058873},
number = 2,
pages = {461-465},
timestamp = {2015-03-17T00:24:22.000+0100},
title = {Bistability and Oscillatory Motion of Natural Nanomembranes Appearing within Monolayer Graphene on Silicon Dioxide},
url = {http://dx.doi.org/10.1021/nl903133w},
volume = 10,
year = 2010
}
5. Electrical transport and low-temperature scanning tunneling microscopy of microsoldered graphene Applied Physics Letters 96, 082114 (2010); doi:10.1063/1.3334730

Using the recently developed technique of microsoldering, we perform systematic transport studies of the influence of polymethylmethacrylate on graphene revealing a doping effect with a n -type dopant density ? n of up to ? n = 3.8 × 10 12 cm – 2 but negligible influence on mobility and hysteresis. Moreover, we show that microsoldered graphene is free of contamination and exhibits very similar intrinsic rippling as found for lithographically contacted flakes. Characterizing the microsoldered sample by scanning tunneling spectroscopy, we demonstrate a current induced closing of the phonon gap and a B-field induced double peak attributed to the 0 Landau level.

@article{:/content/aip/journal/apl/96/8/10.1063/1.3334730,
abstract = {Using the recently developed technique of microsoldering, we perform systematic transport studies of the influence of polymethylmethacrylate on graphene revealing a doping effect with a n -type dopant density ? n of up to ? n = 3.8 × 10 12 cm - 2 but negligible influence on mobility and hysteresis. Moreover, we show that microsoldered graphene is free of contamination and exhibits very similar intrinsic rippling as found for lithographically contacted flakes. Characterizing the microsoldered sample by scanning tunneling spectroscopy, we demonstrate a current induced closing of the phonon gap and a B-field induced double peak attributed to the 0 Landau level.},
author = {Geringer, V. and Subramaniam, D. and Michel, A. K. and Szafranek, B. and Schall, D. and Georgi, A. and Mashoff, T. and Neumaier, D. and Liebmann, M. and Morgenstern, M.},
description = {Electrical transport and low-temperature scanning tunneling microscopy of microsoldered graphene},
doi = {10.1063/1.3334730},
eid = {082114},
journal = {Applied Physics Letters},
keywords = {morgenstern},
number = 8,
timestamp = {2015-03-17T00:24:26.000+0100},
title = {Electrical transport and low-temperature scanning tunneling microscopy of microsoldered graphene},
url = {http://scitation.aip.org/content/aip/journal/apl/96/8/10.1063/1.3334730},
volume = 96,
year = 2010
}
6. STM Ready for the Time Domain Science 329, 1609-1610 (2010); doi:10.1126/science.1194918
@article{Morgenstern24092010,
author = {Morgenstern, Markus},
description = {STM Ready for the Time Domain},
doi = {10.1126/science.1194918},
eprint = {http://www.sciencemag.org/content/329/5999/1609.full.pdf},
interhash = {156746079e769878738197b21533868a},
journal = {Science},
keywords = {morgenstern},
number = 5999,
pages = {1609-1610},
timestamp = {2015-03-17T00:24:37.000+0100},
title = {STM Ready for the Time Domain},
url = {http://www.sciencemag.org/content/329/5999/1609.short},
volume = 329,
year = 2010
}
7. Synthesis of Graphene on Silicon Dioxide by a Solid Carbon Source Nano Letters 10, 36-42 (2010); doi:10.1021/nl902558x

We report on a method for the fabrication of graphene on a silicon dioxide substrate by solid-state dissolution of an overlying stack of a silicon carbide and a nickel thin film. The carbon dissolves in the nickel by rapid thermal annealing. Upon cooling, the carbon segregates to the nickel surface forming a graphene layer over the entire nickel surface. By wet etching of the nickel layer, the graphene layer was allowed to settle on the original substrate. Scanning tunneling microscopy (STM) as well as Raman spectroscopy has been performed for characterization of the layers. Further insight into the morphology of the layers has been gained by Raman mapping indicating micrometer-size graphene grains. Devices for electrical measurement have been manufactured exhibiting a modulation of the transfer current by backgate electric fields. The presented approach allows for mass fabrication of polycrystalline graphene without transfer steps while using only CMOS compatible process steps.

@article{doi:10.1021/nl902558x,
abstract = { We report on a method for the fabrication of graphene on a silicon dioxide substrate by solid-state dissolution of an overlying stack of a silicon carbide and a nickel thin film. The carbon dissolves in the nickel by rapid thermal annealing. Upon cooling, the carbon segregates to the nickel surface forming a graphene layer over the entire nickel surface. By wet etching of the nickel layer, the graphene layer was allowed to settle on the original substrate. Scanning tunneling microscopy (STM) as well as Raman spectroscopy has been performed for characterization of the layers. Further insight into the morphology of the layers has been gained by Raman mapping indicating micrometer-size graphene grains. Devices for electrical measurement have been manufactured exhibiting a modulation of the transfer current by backgate electric fields. The presented approach allows for mass fabrication of polycrystalline graphene without transfer steps while using only CMOS compatible process steps. },
author = {Hofrichter, Jens and Szafranek, BartholomÃ¤us N. and Otto, Martin and Echtermeyer, Tim J. and Baus, Matthias and Majerus, Anne and Geringer, Viktor and Ramsteiner, Manfred and Kurz, Heinrich},
biburl = {http://www.bibsonomy.org/bibtex/2bef78466b1d1c34c1777f6726f069676/institut2b},
description = {Synthesis of Graphene on Silicon Dioxide by a Solid Carbon Source - Nano Letters (ACS Publications)},
doi = {10.1021/nl902558x},
eprint = {http://dx.doi.org/10.1021/nl902558x},
interhash = {5306d341a46303ff88898d52f98125f5},
intrahash = {bef78466b1d1c34c1777f6726f069676},
journal = {Nano Letters},
keywords = {morgenstern},
note = {PMID: 20028105},
number = 1,
pages = {36-42},
timestamp = {2015-03-17T00:25:58.000+0100},
title = {Synthesis of Graphene on Silicon Dioxide by a Solid Carbon Source},
url = {http://dx.doi.org/10.1021/nl902558x},
volume = 10,
year = 2010
}

### 2009

1. Intrinsic and extrinsic corrugation of monolayer graphene deposited on ${\mathrm{SiO}}_{2}$ Phys. Rev. Lett. 102, 076102 (2009); doi:10.1103/PhysRevLett.102.076102
@article{PhysRevLett.102.076102,
author = {Geringer, V. and Liebmann, M. and Echtermeyer, T. and Runte, S. and Schmidt, M. and R\"uckamp, R. and Lemme, M. C. and Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/230aa2fe3fcd4526f4ccb312c18aa0c96/institut2b},
description = {Phys. Rev. Lett. 102, 076102 (2009) - Intrinsic and extrinsic corrugation of monolayer graphene deposited on ${\mathrm{SiO}}_{2}$},
doi = {10.1103/PhysRevLett.102.076102},
intrahash = {30aa2fe3fcd4526f4ccb312c18aa0c96},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = feb,
number = 7,
numpages = {4},
eid = {076102},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:26:09.000+0100},
title = {Intrinsic and extrinsic corrugation of monolayer graphene deposited on ${\mathrm{SiO}}_{2}$},
volume = 102,
year = 2009
}
2. Scanning tunneling microscopy and spectroscopy of the phase change alloy Ge1Sb2Te4 Applied Physics Letters 95, 103110 (2009); doi:10.1063/1.3211991

Scanning tunneling microscopy and spectroscopy have been employed to reveal the evolution of the band gap and the Fermi level as a function of the annealing temperature for Ge 1 Sb 2 Te 4 , a promising material for phase change memory applications. The band gap decreases continuously from 0.65 eV in the amorphous phase via 0.3 eV in the metastable crystalline phase to zero gap in the stable crystalline phase. The Fermi level moves from the center of the gap in the amorphous phase close to the valence band within the crystalline phases. Moreover, the metastable phase has been imaged with atomic resolution, presumably showing the Te lattice at negative sample bias and the Ge/Sb/vacancy lattice at positive bias.

@article{:/content/aip/journal/apl/95/10/10.1063/1.3211991,
abstract = {Scanning tunneling microscopy and spectroscopy have been employed to reveal the evolution of the band gap and the Fermi level as a function of the annealing temperature for Ge 1 Sb 2 Te 4 , a promising material for phase change memory applications. The band gap decreases continuously from 0.65 eV in the amorphous phase via 0.3 eV in the metastable crystalline phase to zero gap in the stable crystalline phase. The Fermi level moves from the center of the gap in the amorphous phase close to the valence band within the crystalline phases. Moreover, the metastable phase has been imaged with atomic resolution, presumably showing the Te lattice at negative sample bias and the Ge/Sb/vacancy lattice at positive bias.},
author = {Subramaniam, D. and Pauly, C. and Liebmann, M. and Woda, M. and Rausch, P. and Merkelbach, P. and Wuttig, M. and Morgenstern, M.},
description = {Scanning tunneling microscopy and spectroscopy of the phase change alloy Ge1Sb2Te4},
doi = {10.1063/1.3211991},
eid = {103110},
interhash = {9360ce832862ebb99d67e80e5986abe6},
journal = {Applied Physics Letters},
keywords = {morgenstern},
number = 10,
timestamp = {2015-03-17T00:26:01.000+0100},
title = {Scanning tunneling microscopy and spectroscopy of the phase change alloy Ge1Sb2Te4},
url = {http://scitation.aip.org/content/aip/journal/apl/95/10/10.1063/1.3211991},
volume = 95,
year = 2009
}
3. A low-temperature high resolution scanning tunneling microscope with a three-dimensional magnetic vector field operating in ultrahigh vacuum Review of Scientific Instruments 80, 053702 (2009); doi:10.1063/1.3127589

We present a low-temperature ultrahigh vacuum (UHV) scanning tunneling microscope setup with a combination of a superconducting solenoid coil and two split-pair magnets, providing a rotatable magnetic field up to 500 mT applicable in all spatial directions. An absolute field maximum of B = 7 T ( 3 T ) can be applied perpendicular (parallel) to the sample surface. The instrument is operated at a temperature of 4.8 K. Topographic and spectroscopic measurements on tungsten carbide and indium antimonide revealed a z -noise of 300 fm pp , which barely changes in magnetic field. The microscope is equipped with a tip exchange mechanism and a lateral sample positioning stage, which allows exact positioning of the tip with an accuracy of 5 µ m prior to the measurement. Additional contacts to the sample holder allow, e.g., the application of an additional gate voltage. The UHV part of the system contains versatile possibilities of in situ sample and tip preparation as well as low-energy electron diffraction and Auger analysis.

@article{:/content/aip/journal/rsi/80/5/10.1063/1.3127589,
abstract = {We present a low-temperature ultrahigh vacuum (UHV) scanning tunneling microscope setup with a combination of a superconducting solenoid coil and two split-pair magnets, providing a rotatable magnetic field up to 500 mT applicable in all spatial directions. An absolute field maximum of B = 7 T ( 3 T ) can be applied perpendicular (parallel) to the sample surface. The instrument is operated at a temperature of 4.8 K. Topographic and spectroscopic measurements on tungsten carbide and indium antimonide revealed a z -noise of 300 fm pp , which barely changes in magnetic field. The microscope is equipped with a tip exchange mechanism and a lateral sample positioning stage, which allows exact positioning of the tip with an accuracy of 5 µ m prior to the measurement. Additional contacts to the sample holder allow, e.g., the application of an additional gate voltage. The UHV part of the system contains versatile possibilities of in situ sample and tip preparation as well as low-energy electron diffraction and Auger analysis.},
author = {Mashoff, T. and Pratzer, M. and Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/272e35a9c9a857f14c7eec517b24ec1ca/institut2b},
description = {A low-temperature high resolution scanning tunneling microscope with a three-dimensional magnetic vector field operating in ultrahigh vacuum},
doi = {10.1063/1.3127589},
eid = {053702},
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intrahash = {72e35a9c9a857f14c7eec517b24ec1ca},
journal = {Review of Scientific Instruments},
keywords = {morgenstern},
number = 5,
timestamp = {2015-03-17T00:26:06.000+0100},
title = {A low-temperature high resolution scanning tunneling microscope with a three-dimensional magnetic vector field operating in ultrahigh vacuum},
url = {http://scitation.aip.org/content/aip/journal/rsi/80/5/10.1063/1.3127589},
volume = 80,
year = 2009
}

### 2008

1. Quantum Hall Transition in Real Space: From Localized to Extended States Phys. Rev. Lett. 101, 256802 (2008); doi:10.1103/PhysRevLett.101.256802
@article{PhysRevLett.101.256802,
author = {Hashimoto, K. and Sohrmann, C. and Wiebe, J. and Inaoka, T. and Meier, F. and Hirayama, Y. and R\"omer, R. A. and Wiesendanger, R. and Morgenstern, M.},
description = {Phys. Rev. Lett. 101, 256802 (2008) - Quantum Hall Transition in Real Space: From Localized to Extended States},
doi = {10.1103/PhysRevLett.101.256802},
interhash = {5bf8fd67f249c9390a00208c9443df7f},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = dec,
number = 25,
numpages = {4},
eid = {256802},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:33:10.000+0100},
title = {Quantum Hall Transition in Real Space: From Localized to Extended States},
volume = 101,
year = 2008
}
2. Anisotropic superexchange in one-dimensional Fe-chains on InAs(1 1 0) Surface Science 602, 3297-3302 (2008); doi:10.1016/j.susc.2008.09.014

The magnetic and electronic properties of Fe chains on InAs(1 1 0) are calculated from first-principles using the density functional theory. The magnetic ground state is found to be antiferromagnetic (AF) for Fe chains along [1 -1 0] direction and ferromagnetic (FM) for Fe chains along the perpendicular [0 0 1] direction. The \{AF\} structure is explained with an \{AF\} superexchange between Fe atoms via mediating As, while the \{FM\} structure is explained with a more complicated exchange path via surface As and In atoms.

@article{Sacharow20083297,
abstract = {The magnetic and electronic properties of Fe chains on InAs(1 1 0) are calculated from first-principles using the density functional theory. The magnetic ground state is found to be antiferromagnetic (AF) for Fe chains along [1 -1 0] direction and ferromagnetic (FM) for Fe chains along the perpendicular [0 0 1] direction. The \{AF\} structure is explained with an \{AF\} superexchange between Fe atoms via mediating As, while the \{FM\} structure is explained with a more complicated exchange path via surface As and In atoms. },
author = {Sacharow, L. and Wiesendanger, R. and Bihlmeyer, G. and Blügel, S. and Morgenstern, M.},
description = {Anisotropic superexchange in one-dimensional Fe-chains on InAs(110)},
doi = {10.1016/j.susc.2008.09.014},
issn = {0039-6028},
journal = {Surface Science },
keywords = {morgenstern},
number = 21,
pages = {3297 - 3302},
timestamp = {2015-03-17T00:32:56.000+0100},
title = {Anisotropic superexchange in one-dimensional Fe-chains on InAs(1 1 0) },
url = {http://www.sciencedirect.com/science/article/pii/S003960280800589X},
volume = 602,
year = 2008
}
3. Metal-insulator transition in graphite: A comparison to heterostructures with high carrier mobility Technical Physics Letters 34, 30-33 (2008); doi:10.1134/S1063785008010094

Conditions for a transition from the insulator (I) to metal (M) state in the electron system of highly oriented pyrolytic graphite (HOPG) have been studied by means of magnetotransport measurements in a broad temperature range (0.3–150 K). In magnetic fields below a certain critical value (

@article{noKey,
abstract = {Conditions for a transition from the insulator (I) to metal (M) state in the electron system of highly oriented pyrolytic graphite (HOPG) have been studied by means of magnetotransport measurements in a broad temperature range (0.3–150 K). In magnetic fields below a certain critical value (},
author = {Konenkova, E.V. and Grundler, D. and Morgenstern, M. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/22585eff5812abf513d96caa21db60069/institut2b},
description = {Metal-insulator transition in graphite: A comparison to heterostructures with high carrier mobility - Springer},
doi = {10.1134/S1063785008010094},
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issn = {1063-7850},
journal = {Technical Physics Letters},
keywords = {morgenstern},
language = {English},
number = 1,
pages = {30-33},
publisher = {SP MAIK Nauka/Interperiodica},
timestamp = {2015-03-17T00:35:07.000+0100},
title = {Metal-insulator transition in graphite: A comparison to heterostructures with high carrier mobility},
url = {http://dx.doi.org/10.1134/S1063785008010094},
volume = 34,
year = 2008
}
4. Direkter Blick auf atomare Bits Physik Journal 7/2008, 16 (2008);
[BibTeX]
@article{morgenstern2008direkter,
author = {Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/271c83bb6086130dd39c6906f1310c5b6/institut2b},
interhash = {96b1d792da8f39df176430b161299e4e},
intrahash = {71c83bb6086130dd39c6906f1310c5b6},
journal = {Physik Journal},
keywords = {morgenstern},
pages = 16,
timestamp = {2015-03-17T04:08:50.000+0100},
title = {Direkter Blick auf atomare Bits},
volume = {7/2008},
year = 2008
}

### 2007

1. Local Electronic Structure near Mn Acceptors in InAs: Surface-Induced Symmetry Breaking and Coupling to Host States Phys. Rev. Lett. 99, 157202 (2007); doi:10.1103/PhysRevLett.99.157202
@article{PhysRevLett.99.157202,
author = {Marczinowski, F. and Wiebe, J. and Tang, J.-M. and Flatt\'e, M. E. and Meier, F. and Morgenstern, M. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/2868960640fddd345216e8a7ddf3bef74/institut2b},
description = {Phys. Rev. Lett. 99, 157202 (2007) - Local Electronic Structure near Mn Acceptors in InAs: Surface-Induced Symmetry Breaking and Coupling to Host States},
doi = {10.1103/PhysRevLett.99.157202},
interhash = {1875047a8a1d509a917c986ef51aa98d},
intrahash = {868960640fddd345216e8a7ddf3bef74},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = oct,
number = 15,
numpages = {4},
eid = {157202},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:41:15.000+0100},
title = {Local Electronic Structure near Mn Acceptors in InAs: Surface-Induced Symmetry Breaking and Coupling to Host States},
volume = 99,
year = 2007
}
2. M. Morgenstern. „Scanning Probe Microscopy on Low-Dimensional Electron Systems in III–V Semiconductors.“ Scanning Probe Microscopy. Eds. S. Kalinin and A. Gruverman. Springer New York, 2007. 349-371. doi:10.1007/978-0-387-28668-6_12

Since the discovery of the quantum Hall effect [

@incollection{noKey,
abstract = {Since the discovery of the quantum Hall effect [},
author = {Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/25d4669d0a7c47586c2c7bec6bcb79846/institut2b},
booktitle = {Scanning Probe Microscopy},
description = {Scanning Probe Microscopy on Low-Dimensional Electron Systems in III–V Semiconductors - Springer},
doi = {10.1007/978-0-387-28668-6_12},
editor = {Kalinin, Sergei and Gruverman, Alexei},
interhash = {f07a5aff1698a276720d1d36b1da2707},
intrahash = {5d4669d0a7c47586c2c7bec6bcb79846},
isbn = {978-0-387-28667-9},
keywords = {morgenstern},
language = {English},
pages = {349-371},
publisher = {Springer New York},
timestamp = {2015-03-17T00:42:16.000+0100},
title = {Scanning Probe Microscopy on Low-Dimensional Electron Systems in III–V Semiconductors},
url = {http://dx.doi.org/10.1007/978-0-387-28668-6_12},
year = 2007
}

### 2006

1. G. Pirug and M. Morgenstern. „3.8.1 H2O on metals.“ Adsorbed Layers on Surfaces. Part 5: Adsorption of molecules on metal, semiconductor and oxide surfaces. Ed. H. P. Bonzel. Vol. 42A5. Landolt-Börnstein – Group III Condensed Matter. Springer Berlin Heidelberg, 2006. 1-36. doi:10.1007/11364856_2

This document is part of Part 5 ‚Adsorption of molecules on metal, semiconductor and oxide surfaces‘ of Subvolume A ‚Adsorbate Layers on Surfaces‘ of Volume 42 ‚Physics of Covered Solid Surfaces‘ of Landolt-Börnstein – Group III Condensed Matter.

@incollection{noKey,
abstract = {This document is part of Part 5 'Adsorption of molecules on metal, semiconductor and oxide surfaces' of Subvolume A 'Adsorbate Layers on Surfaces' of Volume 42 'Physics of Covered Solid Surfaces' of Landolt-Börnstein - Group III Condensed Matter. },
author = {Pirug, G. and Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/267923b3a000da90469d3db9eda89cb25/institut2b},
booktitle = {Adsorbed Layers on Surfaces. Part 5: Adsorption of molecules on metal, semiconductor and oxide surfaces},
description = {3.8.1 H2O on metals - Springer},
doi = {10.1007/11364856_2},
editor = {Bonzel, H.P.},
interhash = {d330b39bdcd64b4ec68000a9e73f29c6},
intrahash = {67923b3a000da90469d3db9eda89cb25},
isbn = {978-3-540-25848-3},
keywords = {morgenstern},
language = {English},
pages = {1-36},
publisher = {Springer Berlin Heidelberg},
series = {Landolt-Börnstein - Group III Condensed Matter},
timestamp = {2015-03-17T00:41:21.000+0100},
title = {3.8.1 H2O on metals},
url = {http://dx.doi.org/10.1007/11364856_2},
volume = {42A5},
year = 2006
}

### 2005

1. M. Morgenstern. „Scanning Tunneling Spectroscopy.“ Scanning Probe Microscopy: Characterization, Nanofabrication and Device Application of Functional Materials. Eds. P. Vilarinho, Y. Rosenwaks, and A. Kingon. Vol. 186. NATO Science Series II: Mathematics, Physics and Chemistry. Springer Netherlands, 2005. 251-273. doi:10.1007/1-4020-3019-3_11

Scanning tunneling spectroscopy (STS) and its extension, the spin-polarized scanning tunneling spectroscopy (SPSTS), reveal basic information on the spatial distribution of electron systems. STS measures the local density of states given by the sum over squared single-particle wave functions at a chosen energy, while SPSTS detects the spatial distribution of the spin at the same energy. The application of these techniques on electron systems, which are not spatially uniform, is of particular interest. Here, we discuss two examples. First, the paradigmatic electron system located in the quasiparabolic conduction band of InAs is investigated and different types of electron phases are identified depending on the dimension of the system and the applied magnetic field. Second, the spin-polarized technique is used to determine the domain configuration of ferromagnetic particles at different heights.

@incollection{noKey,
abstract = {Scanning tunneling spectroscopy (STS) and its extension, the spin-polarized scanning tunneling spectroscopy (SPSTS), reveal basic information on the spatial distribution of electron systems. STS measures the local density of states given by the sum over squared single-particle wave functions at a chosen energy, while SPSTS detects the spatial distribution of the spin at the same energy. The application of these techniques on electron systems, which are not spatially uniform, is of particular interest. Here, we discuss two examples. First, the paradigmatic electron system located in the quasiparabolic conduction band of InAs is investigated and different types of electron phases are identified depending on the dimension of the system and the applied magnetic field. Second, the spin-polarized technique is used to determine the domain configuration of ferromagnetic particles at different heights.},
author = {Morgenstern, M.},
biburl = {http://www.bibsonomy.org/bibtex/202a6bb0e76e41d89a4bf1044c7822e09/institut2b},
booktitle = {Scanning Probe Microscopy: Characterization, Nanofabrication and Device Application of Functional Materials},
description = {Scanning Tunneling Spectroscopy - Springer},
doi = {10.1007/1-4020-3019-3_11},
editor = {Vilarinho, PaulaMaria and Rosenwaks, Yossi and Kingon, Angus},
interhash = {b337b3f85e40f9d2d769874ffc01d4c3},
intrahash = {02a6bb0e76e41d89a4bf1044c7822e09},
isbn = {978-1-4020-3017-8},
keywords = {morgenstern},
language = {English},
pages = {251-273},
publisher = {Springer Netherlands},
series = {NATO Science Series II: Mathematics, Physics and Chemistry},
timestamp = {2015-03-17T00:42:53.000+0100},
title = {Scanning Tunneling Spectroscopy},
url = {http://dx.doi.org/10.1007/1-4020-3019-3_11},
volume = 186,
year = 2005
}

### 2004

1. Contributions of the escape depth to the photoelectron intensity of a well-defined initial state Phys. Rev. B 70, 081305 (2004); doi:10.1103/PhysRevB.70.081305
@article{PhysRevB.70.081305,
author = {Morgenstern, M. and Strasser, T. and Adelung, R. and Getzlaff, M. and Kipp, L. and Skibowski, M. and Schattke, W. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/2f520cbf3dd31df8118f115916cdb5586/institut2b},
description = {Phys. Rev. B 70, 081305(R) (2004) - Contributions of the escape depth to the photoelectron intensity of a well-defined initial state},
doi = {10.1103/PhysRevB.70.081305},
interhash = {85c578e44bf4b91274783f4ca28d303e},
intrahash = {f520cbf3dd31df8118f115916cdb5586},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = aug,
number = 8,
numpages = {4},
eid = {081305},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:46:29.000+0100},
title = {Contributions of the escape depth to the photoelectron intensity of a well-defined initial state},
volume = 70,
year = 2004
}
2. Scanning tunneling spectroscopy on Co(0001): Spectroscopic signature of stacking faults and dislocation lines Phys. Rev. B 70, 035404 (2004); doi:10.1103/PhysRevB.70.035404
@article{PhysRevB.70.035404,
author = {Wiebe, J. and Sacharow, L. and Wachowiak, A. and Bihlmayer, G. and Heinze, S. and Bl\"ugel, S. and Morgenstern, M. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/2a3115d61f600d1a9631d5a6ed4bf576d/institut2b},
description = {Phys. Rev. B 70, 035404 (2004) - Scanning tunneling spectroscopy on Co(0001): Spectroscopic signature of stacking faults and dislocation lines},
doi = {10.1103/PhysRevB.70.035404},
interhash = {95ae3df567e7582a8ab87ea84eeb1735},
intrahash = {a3115d61f600d1a9631d5a6ed4bf576d},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = jul,
number = 3,
numpages = {13},
eid = {035404},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:46:39.000+0100},
title = {Scanning tunneling spectroscopy on Co(0001): Spectroscopic signature of stacking faults and dislocation lines},
volume = 70,
year = 2004
}
3. High spin polarization at the interface between a Fe monolayer and InAs(110) Phys. Rev. B 69, 085317 (2004); doi:10.1103/PhysRevB.69.085317
@article{PhysRevB.69.085317,
author = {Sacharow, L. and Morgenstern, M. and Bihlmayer, G. and Bl\"ugel, S.},
biburl = {http://www.bibsonomy.org/bibtex/2a3cf864d5b0af3e419a2ccd861d731be/institut2b},
description = {Phys. Rev. B 69, 085317 (2004) - High spin polarization at the interface between a Fe monolayer and InAs(110)},
doi = {10.1103/PhysRevB.69.085317},
interhash = {9b3cf79a01b26ae5fcaca45689c689e2},
intrahash = {a3cf864d5b0af3e419a2ccd861d731be},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = feb,
number = 8,
numpages = {5},
eid = {085317},
publisher = {American Physical Society},
timestamp = {2015-03-17T00:44:18.000+0100},
title = {High spin polarization at the interface between a Fe monolayer and InAs(110)},
volume = 69,
year = 2004
}
4. Thickness dependent magnetization states of Fe islands on W(110): From single domain to vortex and diamond patterns Applied Physics Letters 84, 948-950 (2004); doi:10.1063/1.1644613

We have studied the thickness dependent domain configuration of single-crystal nanoscale Fe islands on W(110) by spin-polarized scanning tunneling microscopy. The experimental results are compared with micromagnetic calculations. For very thin islands, the uniaxial surface anisotropy of Fe/W(110) leads to a single domain state. With increasing island thickness, the magnetostatic energy becomes increasingly important resulting in different flux closure configurations.

@article{:/content/aip/journal/apl/84/6/10.1063/1.1644613,
abstract = {We have studied the thickness dependent domain configuration of single-crystal nanoscale Fe islands on W(110) by spin-polarized scanning tunneling microscopy. The experimental results are compared with micromagnetic calculations. For very thin islands, the uniaxial surface anisotropy of Fe/W(110) leads to a single domain state. With increasing island thickness, the magnetostatic energy becomes increasingly important resulting in different flux closure configurations.},
author = {Bode, M. and Wachowiak, A. and Wiebe, J. and Kubetzka, A. and Morgenstern, M. and Wiesendanger, R.},
description = {Thickness dependent magnetization states of Fe islands on W(110): From single domain to vortex and diamond patterns},
doi = {10.1063/1.1644613},
eid = {948},
interhash = {61e3889a4235474e6092f5f9413af89b},
journal = {Applied Physics Letters},
keywords = {morgenstern},
number = 6,
pages = {948-950},
timestamp = {2015-03-17T00:44:24.000+0100},
title = {Thickness dependent magnetization states of Fe islands on W(110): From single domain to vortex and diamond patterns},
url = {http://scitation.aip.org/content/aip/journal/apl/84/6/10.1063/1.1644613},
volume = 84,
year = 2004
}
5. A 300 mK ultra-high vacuum scanning tunneling microscope for spin-resolved spectroscopy at high energy resolution Review of Scientific Instruments 75, 4871-4879 (2004); doi:10.1063/1.1794431

We describe the design and development of a scanning tunneling micoscope (STM) working at very low temperatures in ultra-high vacuum (UHV) and at high magnetic fields. The STM is mounted to the 3 He pot of an entirely UHV compatible 3 He refrigerator inside a tube which can be baked out to achieve UHV conditions even at room temperature. A base temperature of 315 mK with a hold time of 30 h without any recondensing or refilling of cryogenics is achieved. The STM can be moved from the cryostat into a lower UHV-chamber system where STM-tips and -samples can be exchanged without breaking UHV. The chambers contain standard surface science tools for preparation and characterization of tips and samples in particular for spin-resolved scanning tunnelingspectroscopy (STS). Test measurements using either superconducting tips or samples show that the system is adequate for performing STS with both high spatial and high energy resolution. The vertical stability of the tunnel junction is shown to be 5 pm pp and the energy resolution is about 100 µ eV .

@article{:/content/aip/journal/rsi/75/11/10.1063/1.1794431,
abstract = {We describe the design and development of a scanning tunneling micoscope (STM) working at very low temperatures in ultra-high vacuum (UHV) and at high magnetic fields. The STM is mounted to the 3 He pot of an entirely UHV compatible 3 He refrigerator inside a tube which can be baked out to achieve UHV conditions even at room temperature. A base temperature of 315 mK with a hold time of 30 h without any recondensing or refilling of cryogenics is achieved. The STM can be moved from the cryostat into a lower UHV-chamber system where STM-tips and -samples can be exchanged without breaking UHV. The chambers contain standard surface science tools for preparation and characterization of tips and samples in particular for spin-resolved scanning tunnelingspectroscopy (STS). Test measurements using either superconducting tips or samples show that the system is adequate for performing STS with both high spatial and high energy resolution. The vertical stability of the tunnel junction is shown to be 5 pm pp and the energy resolution is about 100 µ eV .},
author = {Wiebe, J. and Wachowiak, A. and Meier, F. and Haude, D. and Foster, T. and Morgenstern, M. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/2704e098834182955993e051b1072a6d7/institut2b},
description = {A 300 mK ultra-high vacuum scanning tunneling microscope for spin-resolved spectroscopy at high energy resolution},
doi = {10.1063/1.1794431},
eid = {4871},
interhash = {93d84f1f89bc0cb511c590779d629d31},
intrahash = {704e098834182955993e051b1072a6d7},
journal = {Review of Scientific Instruments},
keywords = {morgenstern},
number = 11,
pages = {4871-4879},
timestamp = {2015-03-17T00:50:33.000+0100},
title = {A 300 mK ultra-high vacuum scanning tunneling microscope for spin-resolved spectroscopy at high energy resolution},
url = {http://scitation.aip.org/content/aip/journal/rsi/75/11/10.1063/1.1794431},
volume = 75,
year = 2004
}
6. M. Morgenstern, A. Schwarz, and U. Schwarz. „Low Temperature Scanning Probe Microscopy.“ Springer Handbook of Nanotechnology. Ed. B. Bhushan. Springer Berlin Heidelberg, 2004. 413-447. doi:10.1007/3-540-29838-X_14

This chapter is dedicated to scanning probe microscopy, one of the most important techniques in nanotechnology. In general, scanning probe techniques allow the measurement of physical properties down to the nanometer scale. Some techniques, such as the scanning tunneling microscope and the scanning force microscope even go down to the atomic scale. The properties that are accessible are various. Most importantly, one can image the arrangement of atoms on conducting surfaces by scanning tunneling microscopy and on insulating substrates by scanning force microscopy. But also the arrangement of electrons (scanning tunneling spectroscopy), the force interaction between different atoms (scanning force spectroscopy), magnetic domains (magnetic force microscopy), the local capacitance (scanning capacitance microscopy), the local temperature (scanning thermo microscopy), and local light-induced excitations (scanning near-field microscopy) can be measured with high spatial resolution. In addition, some techniques even allow the manipulation of atomic configurations.

@incollection{noKey,
abstract = {This chapter is dedicated to scanning probe microscopy, one of the most important techniques in nanotechnology. In general, scanning probe techniques allow the measurement of physical properties down to the nanometer scale. Some techniques, such as the scanning tunneling microscope and the scanning force microscope even go down to the atomic scale. The properties that are accessible are various. Most importantly, one can image the arrangement of atoms on conducting surfaces by scanning tunneling microscopy and on insulating substrates by scanning force microscopy. But also the arrangement of electrons (scanning tunneling spectroscopy), the force interaction between different atoms (scanning force spectroscopy), magnetic domains (magnetic force microscopy), the local capacitance (scanning capacitance microscopy), the local temperature (scanning thermo microscopy), and local light-induced excitations (scanning near-field microscopy) can be measured with high spatial resolution. In addition, some techniques even allow the manipulation of atomic configurations.},
author = {Morgenstern, Markus and Schwarz, Alexander and Schwarz, UdoD.},
booktitle = {Springer Handbook of Nanotechnology},
description = {Low Temperature Scanning Probe Microscopy - Springer},
doi = {10.1007/3-540-29838-X_14},
editor = {Bhushan, Bharat},
interhash = {64647a33c478cc8373689583325d960b},
isbn = {978-3-540-01218-4},
keywords = {morgenstern},
language = {English},
pages = {413-447},
publisher = {Springer Berlin Heidelberg},
timestamp = {2015-03-17T00:58:02.000+0100},
title = {Low Temperature Scanning Probe Microscopy},
url = {http://dx.doi.org/10.1007/3-540-29838-X_14},
year = 2004
}
7. Fundamental studies of magnetism down to the atomic scale: present status and future perspectives of spin-polarized scanning tunneling microscopy Journal of Magnetism and Magnetic Materials 272–276, Part 3, 2115-2120 (2004); doi:10.1016/j.jmmm.2003.12.817

Recent developments in spin-polarized scanning tunneling microscopy and spectroscopy have led to an unprecedented insight into magnetism at the nanometer length scale and, in some cases, even down to the atomic level. The correlation between structural, local electronic and local magnetic structure can now be studied beyond the exchange length. Most striking recent results include the discovery of atomically sharp magnetic domain walls in atomic layers of iron and the determination of the intrinsic width of magnetic vortex cores in three-dimensional iron islands.

@article{Wiesendanger20042115,
abstract = {Recent developments in spin-polarized scanning tunneling microscopy and spectroscopy have led to an unprecedented insight into magnetism at the nanometer length scale and, in some cases, even down to the atomic level. The correlation between structural, local electronic and local magnetic structure can now be studied beyond the exchange length. Most striking recent results include the discovery of atomically sharp magnetic domain walls in atomic layers of iron and the determination of the intrinsic width of magnetic vortex cores in three-dimensional iron islands. },
author = {Wiesendanger, R. and Bode, M. and Kubetzka, A. and Pietzsch, O. and Morgenstern, M. and Wachowiak, A. and Wiebe, J.},
biburl = {http://www.bibsonomy.org/bibtex/2ae173d088eb02faf07fb13e03c69b489/institut2b},
description = {Fundamental studies of magnetism down to the atomic scale: present status and future perspectives of spin-polarized scanning tunneling microscopy},
doi = {10.1016/j.jmmm.2003.12.817},
interhash = {e8e7f5563fa170b804a40b9fca10c626},
intrahash = {ae173d088eb02faf07fb13e03c69b489},
issn = {0304-8853},
journal = {Journal of Magnetism and Magnetic Materials },
keywords = {morgenstern},
note = {Proceedings of the International Conference on Magnetism (ICM 2003) },
number = 0,
pages = {2115 - 2120},
timestamp = {2015-03-17T00:57:35.000+0100},
title = {Fundamental studies of magnetism down to the atomic scale: present status and future perspectives of spin-polarized scanning tunneling microscopy },
url = {http://www.sciencedirect.com/science/article/pii/S0304885303017803},
volume = {272–276, Part 3},
year = 2004
}
8. Der direkte Blick auf Elektronensysteme Physik Journal 3, 83-88 (2004);
[BibTeX]
@article{morgenstern2004preistragerder,
author = {Morgenstern, Markus},
biburl = {http://www.bibsonomy.org/bibtex/2dfbb138f4ca31c2820a2456eaf91a449/institut2b},
interhash = {3ab275b9f6591dd2b480d98049ddfcc4},
intrahash = {dfbb138f4ca31c2820a2456eaf91a449},
journal = {Physik Journal},
keywords = {morgenstern},
number = 8,
pages = {83-88},
timestamp = {2015-03-17T04:01:39.000+0100},
title = {Der direkte Blick auf Elektronensysteme},
volume = 3,
year = 2004
}

### 2003

1. Wave-Function Mapping of InAs Quantum Dots by Scanning Tunneling Spectroscopy Phys. Rev. Lett. 91, 196804 (2003); doi:10.1103/PhysRevLett.91.196804
@article{PhysRevLett.91.196804,
author = {Maltezopoulos, Theophilos and Bolz, Arne and Meyer, Christian and Heyn, Christian and Hansen, Wolfgang and Morgenstern, Markus and Wiesendanger, Roland},
biburl = {http://www.bibsonomy.org/bibtex/269e2d3ab8ef2854de2d924c94ff915cf/institut2b},
description = {Phys. Rev. Lett. 91, 196804 (2003) - Wave-Function Mapping of InAs Quantum Dots by Scanning Tunneling Spectroscopy},
doi = {10.1103/PhysRevLett.91.196804},
interhash = {535a3d05a93e8365473e802ba3dd42fb},
intrahash = {69e2d3ab8ef2854de2d924c94ff915cf},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = nov,
number = 19,
numpages = {4},
eid = {196804},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:00:41.000+0100},
title = {Wave-Function Mapping of InAs Quantum Dots by Scanning Tunneling Spectroscopy},
volume = 91,
year = 2003
}
2. Direct Measurement of the Local Density of States of a Disordered One-Dimensional Conductor Phys. Rev. Lett. 91, 076803 (2003); doi:10.1103/PhysRevLett.91.076803
@article{PhysRevLett.91.076803,
author = {Meyer, Chr. and Klijn, J. and Morgenstern, M. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/281e4794e4c297de391137a78c73645b4/institut2b},
description = {Phys. Rev. Lett. 91, 076803 (2003) - Direct Measurement of the Local Density of States of a Disordered One-Dimensional Conductor},
doi = {10.1103/PhysRevLett.91.076803},
interhash = {d7b142157053658decafbd5d49252bc2},
intrahash = {81e4794e4c297de391137a78c73645b4},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = aug,
number = 7,
numpages = {4},
eid = {076803},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:00:35.000+0100},
title = {Direct Measurement of the Local Density of States of a Disordered One-Dimensional Conductor},
volume = 91,
year = 2003
}
3. From quantized states to percolation: Scanning tunneling spectroscopy of a strongly disordered two-dimensional electron system Phys. Rev. B 68, 041402 (2003); doi:10.1103/PhysRevB.68.041402
@article{PhysRevB.68.041402,
author = {Wiebe, J. and Meyer, Chr. and Klijn, J. and Morgenstern, M. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/27d3cd1d42b5b8071bb798aa9360ed5ff/institut2b},
description = {Phys. Rev. B 68, 041402(R) (2003) - From quantized states to percolation: Scanning tunneling spectroscopy of a strongly disordered two-dimensional electron system},
doi = {10.1103/PhysRevB.68.041402},
intrahash = {7d3cd1d42b5b8071bb798aa9360ed5ff},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = jul,
number = 4,
numpages = {4},
eid = {041402},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:00:47.000+0100},
title = {From quantized states to percolation: Scanning tunneling spectroscopy of a strongly disordered two-dimensional electron system},
volume = 68,
year = 2003
}
4. Real-Space Observation of Drift States in a Two-Dimensional Electron System at High Magnetic Fields Phys. Rev. Lett. 90, 056804 (2003); doi:10.1103/PhysRevLett.90.056804
@article{PhysRevLett.90.056804,
author = {Morgenstern, M. and Klijn, J. and Meyer, Chr. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/2a62f43cfc39d72e436fa852582806c62/institut2b},
description = {Phys. Rev. Lett. 90, 056804 (2003) - Real-Space Observation of Drift States in a Two-Dimensional Electron System at High Magnetic Fields},
doi = {10.1103/PhysRevLett.90.056804},
interhash = {9a86369f402593cf4c415095720cd334},
intrahash = {a62f43cfc39d72e436fa852582806c62},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = feb,
number = 5,
numpages = {4},
eid = {056804},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:00:38.000+0100},
title = {Real-Space Observation of Drift States in a Two-Dimensional Electron System at High Magnetic Fields},
volume = 90,
year = 2003
}
5. Direct observation of confined states in metallic single-walled carbon nanotubes Applied Physics Letters 83, 1011-1013 (2003); doi:10.1063/1.1598282

We investigated the local density of states (LDOS) of extended individual metallic single-walled carbon nanotubes using low-temperature scanning tunneling spectroscopy. We observed that the LDOS oscillates with energy close to the Fermi level. The oscillation period of about 50 meV varies with position on the nanotube. Maps of the LDOS reveal that the peaks in the oscillation are related to confined states. The widths of the peaks increase with increasing distance from the Fermi level.

@article{:/content/aip/journal/apl/83/5/10.1063/1.1598282,
abstract = {We investigated the local density of states (LDOS) of extended individual metallic single-walled carbon nanotubes using low-temperature scanning tunneling spectroscopy. We observed that the LDOS oscillates with energy close to the Fermi level. The oscillation period of about 50 meV varies with position on the nanotube. Maps of the LDOS reveal that the peaks in the oscillation are related to confined states. The widths of the peaks increase with increasing distance from the Fermi level.},
author = {Maltezopoulos, Theophilos and Kubetzka, André and Morgenstern, Markus and Wiesendanger, Roland and Lemay, Serge G. and Dekker, Cees},
biburl = {http://www.bibsonomy.org/bibtex/2a11610fa285b738f3724f72ec8e3167c/institut2b},
description = {Direct observation of confined states in metallic single-walled carbon nanotubes},
doi = {10.1063/1.1598282},
eid = {1011},
interhash = {2e2b3dd761b38176b8a0085681b37421},
intrahash = {a11610fa285b738f3724f72ec8e3167c},
journal = {Applied Physics Letters},
keywords = {morgenstern},
number = 5,
pages = {1011-1013},
timestamp = {2015-03-17T01:00:44.000+0100},
title = {Direct observation of confined states in metallic single-walled carbon nanotubes},
url = {http://scitation.aip.org/content/aip/journal/apl/83/5/10.1063/1.1598282},
volume = 83,
year = 2003
}
6. STM measurements on the InAs(110) surface directly compared with surface electronic structure calculations Phys. Rev. B 68, 205327 (2003); doi:10.1103/PhysRevB.68.205327
@article{PhysRevB.68.205327,
author = {Klijn, Jan and Sacharow, Lilli and Meyer, Christian and Bl\"ugel, Stefan and Morgenstern, Markus and Wiesendanger, Roland},
biburl = {http://www.bibsonomy.org/bibtex/20ccbb7bd1a301fc282023696b1d61214/institut2b},
description = {Phys. Rev. B 68, 205327 (2003) - STM measurements on the InAs(110) surface directly compared with surface electronic structure calculations},
doi = {10.1103/PhysRevB.68.205327},
interhash = {6e66574d1b23477173bd1204dc060c0b},
intrahash = {0ccbb7bd1a301fc282023696b1d61214},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = nov,
number = 20,
numpages = {10},
eid = {205327},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:00:50.000+0100},
title = {STM measurements on the InAs(110) surface directly compared with surface electronic structure calculations},
volume = 68,
year = 2003
}
7. PROBING THE LOCAL DENSITY OF STATES OF DILUTE ELECTRON SYSTEMS IN DIFFERENT DIMENSIONS Surface Review and Letters 10, 933-962 (2003); doi:10.1142/S0218625X0300575X

<p class="first">Scanning tunneling spectroscopy at T = 6 K is used to investigate the local density of states (LDOS) of electron systems belonging to the bulk conduction band of InAs. In particular, the three-dimensional electron system (3DES) of the n-doped material, an adsorbate-induced two-dimensional electron system (2DES) and the tip-induced quantum dot (0DES) are investigated at B = 0 T and B = 6 T. It is found that the 3DES at B = 0 T can be described by Bloch states weakly interacting with the potential disorder provided by ionized dopants. The 2DES at B = 0 T exhibits much stronger LDOS corrugations, stressing the tendency for weak localization in the potential disorder. In a magnetic field, 3DES and 2DES show drift states, which are expected in 2D, but are surprising in 3D, where they point to a new electron phase consisting of droplets of quasi-2D systems.</p> <p class="last">The 0DES at B = 0 T reveals quantized states in accordance with Hartree calculations. At B = 6 T it exhibits Landau states with exchange enhanced spin splitting. These states are used to investigate the influence of potential disorder on the exchange enhancement, which visualizes the nonlocality of the exchange interaction.</p>

@article{doi:10.1142/S0218625X0300575X,
abstract = { <p class="first">Scanning tunneling spectroscopy at T = 6 K is used to investigate the local density of states (LDOS) of electron systems belonging to the bulk conduction band of InAs. In particular, the three-dimensional electron system (3DES) of the n-doped material, an adsorbate-induced two-dimensional electron system (2DES) and the tip-induced quantum dot (0DES) are investigated at B = 0 T and B = 6 T. It is found that the 3DES at B = 0 T can be described by Bloch states weakly interacting with the potential disorder provided by ionized dopants. The 2DES at B = 0 T exhibits much stronger LDOS corrugations, stressing the tendency for weak localization in the potential disorder. In a magnetic field, 3DES and 2DES show drift states, which are expected in 2D, but are surprising in 3D, where they point to a new electron phase consisting of droplets of quasi-2D systems.</p> <p class="last">The 0DES at B = 0 T reveals quantized states in accordance with Hartree calculations. At B = 6 T it exhibits Landau states with exchange enhanced spin splitting. These states are used to investigate the influence of potential disorder on the exchange enhancement, which visualizes the nonlocality of the exchange interaction.</p> },
author = {MORGENSTERN, MARKUS},
biburl = {http://www.bibsonomy.org/bibtex/22f079edcc64eb30a74ea2ba25ffcce09/institut2b},
description = {PROBING THE LOCAL DENSITY OF STATES OF DILUTE ELECTRON SYSTEMS IN DIFFERENT DIMENSIONS (World Scientific)},
doi = {10.1142/S0218625X0300575X},
eprint = {http://www.worldscientific.com/doi/pdf/10.1142/S0218625X0300575X},
interhash = {21c01b4940cd2b63e553feeb32d48d9d},
intrahash = {2f079edcc64eb30a74ea2ba25ffcce09},
journal = {Surface Review and Letters},
keywords = {morgenstern},
number = 06,
pages = {933-962},
timestamp = {2015-03-17T01:00:58.000+0100},
title = {PROBING THE LOCAL DENSITY OF STATES OF DILUTE ELECTRON SYSTEMS IN DIFFERENT DIMENSIONS},
url = {http://www.worldscientific.com/doi/abs/10.1142/S0218625X0300575X},
volume = 10,
year = 2003
}
8. Comparing measured and calculated local density of states in a disordered two-dimensional electron system Physica B: Condensed Matter 329–333, Part 2, 1536-1537 (2003); doi:10.1016/S0921-4526(02)02279-2

The local density of states (LDOS) of the adsorbate induced two-dimensional electron system (2DES) on n-InAs(110) is studied by low-temperature scanning tunneling spectroscopy. In contrast to a similar 3DES, the 2DES \{LDOS\} exhibits 20 times stronger corrugations and rather irregular structures. Both results are interpreted as a consequence of weak localization. Fourier transforms of the \{LDOS\} reveal that the k-values of the unperturbed 2DES still dominate the 2DES, but additional lower k-values contribute significantly. To clarify the origin of the \{LDOS\} patterns, we measure the potential landscape of the same 2DES area allowing to calculate the expected \{LDOS\} from the single particle Schrödinger equation and to directly compare it with the measured one.

@article{Morgenstern20031536,
abstract = {The local density of states (LDOS) of the adsorbate induced two-dimensional electron system (2DES) on n-InAs(110) is studied by low-temperature scanning tunneling spectroscopy. In contrast to a similar 3DES, the 2DES \{LDOS\} exhibits 20 times stronger corrugations and rather irregular structures. Both results are interpreted as a consequence of weak localization. Fourier transforms of the \{LDOS\} reveal that the k-values of the unperturbed 2DES still dominate the 2DES, but additional lower k-values contribute significantly. To clarify the origin of the \{LDOS\} patterns, we measure the potential landscape of the same 2DES area allowing to calculate the expected \{LDOS\} from the single particle Schrödinger equation and to directly compare it with the measured one. },
author = {Morgenstern, M. and Klijn, J. and Meyer, Chr. and Römer, R.A. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/2f71d2c20eaef16cf788f44a748cb6c10/institut2b},
description = {Comparing measured and calculated local density of states in a disordered two-dimensional electron system},
doi = {10.1016/S0921-4526(02)02279-2},
interhash = {3ef951769bf42b99026cd94d7639926e},
intrahash = {f71d2c20eaef16cf788f44a748cb6c10},
issn = {0921-4526},
journal = {Physica B: Condensed Matter },
keywords = {morgenstern},
note = {Proceedings of the 23rd International Conference on Low Temperature Physics },
number = 0,
pages = {1536 - 1537},
timestamp = {2015-03-17T01:00:55.000+0100},
title = {Comparing measured and calculated local density of states in a disordered two-dimensional electron system },
url = {http://www.sciencedirect.com/science/article/pii/S0921452602022792},
volume = {329–333, Part 2},
year = 2003
}
9. Low Density Two-Dimensional Electron Systems Studied by Scanning Tunneling Spectroscopy Japanese Journal of Applied Physics 42, 4809 (2003);

A two-dimensional electron system (2DES) belonging to the InAs conduction band has been prepared by depositing tiny amounts of adsorbates on the InAs(110) surface. Photoemission has been used to determine the resulting 2DES subband energies. Since the 2DES is close to the surface, it could be probed by low-temperature scanning tunneling spectroscopy. In zero magnetic field we find strong and rather irregular corrugations of the local density of states (LDOS), which are interpreted as due to the tendency of a 2DES to weakly localize. Applying a magnetic field leads to Landau quantization and to a dramatic change of the LDOS, which is now composed of drift states running along equipotential lines.

@article{1347-4065-42-7S-4809,
abstract = {A two-dimensional electron system (2DES) belonging to the InAs conduction band has been prepared by depositing tiny amounts of adsorbates on the InAs(110) surface. Photoemission has been used to determine the resulting 2DES subband energies. Since the 2DES is close to the surface, it could be probed by low-temperature scanning tunneling spectroscopy. In zero magnetic field we find strong and rather irregular corrugations of the local density of states (LDOS), which are interpreted as due to the tendency of a 2DES to weakly localize. Applying a magnetic field leads to Landau quantization and to a dramatic change of the LDOS, which is now composed of drift states running along equipotential lines.},
author = {Morgenstern, Markus and Klijn, Jan and Meyer, Christian and Getzlaff, Mathias and Johnson, Robert L. and Adelung, Rainer and Kipp, Lutz and Römer, Rudolf A. and Wiesendanger, Roland},
biburl = {http://www.bibsonomy.org/bibtex/2907ea790cfd4d8ff13cb887ded773496/institut2b},
description = {Low Density Two-Dimensional Electron Systems Studied by Scanning Tunneling Spectroscopy - Abstract - Japanese Journal of Applied Physics - IOPscience},
interhash = {20a1ae615c5e7bc1891437f02b565291},
intrahash = {907ea790cfd4d8ff13cb887ded773496},
journal = {Japanese Journal of Applied Physics},
keywords = {morgenstern},
number = {7S},
pages = {4809},
timestamp = {2015-03-17T01:00:53.000+0100},
title = {Low Density Two-Dimensional Electron Systems Studied by Scanning Tunneling Spectroscopy},
url = {http://stacks.iop.org/1347-4065/42/i=7S/a=4809},
volume = 42,
year = 2003
}
10. Comparing the local density of states of three- and two-dimensional electron systems by low-temperature scanning tunneling spectroscopy Physica E: Low-dimensional Systems and Nanostructures 16, 121-128 (2003);

Scanning tunneling spectroscopy performed at T=6 K is used to investigate the local density of states (LDOS) of electron systems in the bulk conduction band of InAs. In particular, the 3DES of the n-doped material and an adsorbate-induced 2DES located at the surface are investigated at B=0 and 6 T. It is found that the 3DES at B=0 T can be described by Bloch states weakly interacting with the potential disorder. The 2DES at B=0 T exhibits much stronger \{LDOS\} corrugations revealing the tendency of weak localization. In a magnetic field both systems show drift states, which are expected in 2D, but are surprising in 3D, where they point to a new electron phase consisting of droplets of quasi 2D-systems.

@article{noauthororeditor,
abstract = {Scanning tunneling spectroscopy performed at T=6 K is used to investigate the local density of states (LDOS) of electron systems in the bulk conduction band of InAs. In particular, the 3DES of the n-doped material and an adsorbate-induced 2DES located at the surface are investigated at B=0 and 6 T. It is found that the 3DES at B=0 T can be described by Bloch states weakly interacting with the potential disorder. The 2DES at B=0 T exhibits much stronger \{LDOS\} corrugations revealing the tendency of weak localization. In a magnetic field both systems show drift states, which are expected in 2D, but are surprising in 3D, where they point to a new electron phase consisting of droplets of quasi 2D-systems.},
author = {Morgenstern, M. and Haude, D. and Klijn, J. and Meyer, Chr. and Sacharow, L. and Heinze, S. and Blügel, S. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/290f849424345243d1a802d50b7398cfe/institut2b},
interhash = {68a0a4b33fe4458b3a26353f183f1d18},
intrahash = {90f849424345243d1a802d50b7398cfe},
journal = {Physica E: Low-dimensional Systems and Nanostructures},
keywords = {morgenstern},
number = 1,
pages = {121-128},
timestamp = {2015-03-17T04:10:08.000+0100},
title = {Comparing the local density of states of three- and two-dimensional electron systems by low-temperature scanning tunneling spectroscopy},
url = {http://www.sciencedirect.com/science/article/pii/S1386947702005854},
volume = 16,
year = 2003
}

### 2002

1. Coulomb pseudogap caused by partial localization of a three-dimensional electron system in the extreme quantum limit Phys. Rev. B 66, 121102 (2002); doi:10.1103/PhysRevB.66.121102
@article{PhysRevB.66.121102,
author = {Morgenstern, M. and Haude, D. and Klijn, J. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/20a95a531cb977eb5aa5971dd734248ab/institut2b},
description = {Phys. Rev. B 66, 121102(R) (2002) - Coulomb pseudogap caused by partial localization of a three-dimensional electron system in the extreme quantum limit},
doi = {10.1103/PhysRevB.66.121102},
interhash = {bd68959000d9e1775cd49bb354f59239},
intrahash = {0a95a531cb977eb5aa5971dd734248ab},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = sep,
number = 12,
numpages = {4},
eid = {121102},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:09:13.000+0100},
title = {Coulomb pseudogap caused by partial localization of a three-dimensional electron system in the extreme quantum limit},
volume = 66,
year = 2002
}
2. Direct Comparison between Potential Landscape and Local Density of States in a Disordered Two-Dimensional Electron System Phys. Rev. Lett. 89, 136806 (2002); doi:10.1103/PhysRevLett.89.136806
@article{PhysRevLett.89.136806,
author = {Morgenstern, M. and Klijn, J. and Meyer, Chr. and Getzlaff, M. and Adelung, R. and R\"omer, R. A. and Rossnagel, K. and Kipp, L. and Skibowski, M. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/226428e10c13c787932610bb8cdc1693b/institut2b},
description = {Phys. Rev. Lett. 89, 136806 (2002) - Direct Comparison between Potential Landscape and Local Density of States in a Disordered Two-Dimensional Electron System},
doi = {10.1103/PhysRevLett.89.136806},
interhash = {ff060acd7655047364fc2c66ba5a2bbf},
intrahash = {26428e10c13c787932610bb8cdc1693b},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = sep,
number = 13,
numpages = {4},
eid = {136806},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:09:16.000+0100},
title = {Direct Comparison between Potential Landscape and Local Density of States in a Disordered Two-Dimensional Electron System},
volume = 89,
year = 2002
}
3. Co on \textitp -InAs(110): An island-induced two-dimensional electron system consisting of electron droplets Phys. Rev. B 65, 155325 (2002); doi:10.1103/PhysRevB.65.155325
@article{PhysRevB.65.155325,
author = {Morgenstern, M. and Wiebe, J. and Wachowiak, A. and Getzlaff, M. and Klijn, J. and Plucinski, L. and Johnson, R. L. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/26bf4968b47b02eaffd2a5f0b0e5a4b3b/institut2b},
description = {Phys. Rev. B 65, 155325 (2002) - Co on p-InAs(110): An island-induced two-dimensional electron system consisting of electron droplets},
doi = {10.1103/PhysRevB.65.155325},
interhash = {8b7a1e19417ca159dd9a4f3f62f0dcbf},
intrahash = {6bf4968b47b02eaffd2a5f0b0e5a4b3b},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = apr,
number = 15,
numpages = {8},
eid = {155325},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:09:19.000+0100},
title = {Co on \textit{p} -InAs(110): An island-induced two-dimensional electron system consisting of electron droplets},
volume = 65,
year = 2002
}
4. Direct Observation of Internal Spin Structure of Magnetic Vortex Cores Science 298, 577-580 (2002); doi:10.1126/science.1075302

Thin film nanoscale elements with a curling magnetic structure (vortex) are a promising candidate for future nonvolatile data storage devices. Their properties are strongly influenced by the spin structure in the vortex core. We have used spin-polarized scanning tunneling microscopy on nanoscale iron islands to probe for the first time the internal spin structure of magnetic vortex cores. Using tips coated with a layer of antiferromagnetic chromium, we obtained images of the curling in-plane magnetization around and of the out-of-plane magnetization inside the core region. The experimental data are compared with micromagnetic simulations. The results confirm theoretical predictions that the size and the shape of the vortex core as well as its magnetic field dependence are governed by only two material parameters, the exchange stiffness and the saturation magnetization that determines the stray field energy.

@article{Wachowiak18102002,
abstract = {Thin film nanoscale elements with a curling magnetic structure (vortex) are a promising candidate for future nonvolatile data storage devices. Their properties are strongly influenced by the spin structure in the vortex core. We have used spin-polarized scanning tunneling microscopy on nanoscale iron islands to probe for the first time the internal spin structure of magnetic vortex cores. Using tips coated with a layer of antiferromagnetic chromium, we obtained images of the curling in-plane magnetization around and of the out-of-plane magnetization inside the core region. The experimental data are compared with micromagnetic simulations. The results confirm theoretical predictions that the size and the shape of the vortex core as well as its magnetic field dependence are governed by only two material parameters, the exchange stiffness and the saturation magnetization that determines the stray field energy.},
author = {Wachowiak, A. and Wiebe, J. and Bode, M. and Pietzsch, O. and Morgenstern, M. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/228faf6b4d081e20f34f402b074f73086/institut2b},
description = {Direct Observation of Internal Spin Structure of Magnetic Vortex Cores},
doi = {10.1126/science.1075302},
eprint = {http://www.sciencemag.org/content/298/5593/577.full.pdf},
interhash = {4572c386090ccbab56e3a2dd1615f1b6},
intrahash = {28faf6b4d081e20f34f402b074f73086},
journal = {Science},
keywords = {morgenstern},
number = 5593,
pages = {577-580},
timestamp = {2015-03-17T01:09:10.000+0100},
title = {Direct Observation of Internal Spin Structure of Magnetic Vortex Cores},
url = {http://www.sciencemag.org/content/298/5593/577.abstract},
volume = 298,
year = 2002
}
5. Influence of potential fluctuations on Landau quantization and spin splitting studied by low temperature scanning tunneling spectroscopy on InAs(110) Journal of Vacuum Science & Technology B 20, 2032-2035 (2002); doi:10.1116/1.1506906

The Landau quantization visible in dI/dV spectra on n-InAs(110) at B=6 T and T=8 K is studied with high spatial resolution. It is found that the dI/dV intensity is dominated by the Landau bands of the tip-induced quantum dot. The Landau band energies depend on the local surface potential provided by the ionized dopants. Comparison with Hartree–Fock calculations show that the energy shifts are accompanied by an enhanced spin splitting of the Landau bands induced by the spatially varying spin polarization of the dot. Imaging of the spin splitting demonstrates the nonsimple dependence of the spin polarization on the local potential.

@article{:/content/avs/journal/jvstb/20/5/10.1116/1.1506906,
abstract = {The Landau quantization visible in dI/dV spectra on n-InAs(110) at B=6 T and T=8 K is studied with high spatial resolution. It is found that the dI/dV intensity is dominated by the Landau bands of the tip-induced quantum dot. The Landau band energies depend on the local surface potential provided by the ionized dopants. Comparison with Hartree–Fock calculations show that the energy shifts are accompanied by an enhanced spin splitting of the Landau bands induced by the spatially varying spin polarization of the dot. Imaging of the spin splitting demonstrates the nonsimple dependence of the spin polarization on the local potential.},
author = {Morgenstern, M. and Gudmundsson, V. and Wiesendanger, R.},
description = {Influence of potential fluctuations on Landau quantization and spin splitting studied by low temperature scanning tunneling spectroscopy on InAs(110)},
doi = {10.1116/1.1506906},
eid = {2032},
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journal = {Journal of Vacuum Science & Technology B},
keywords = {morgenstern},
number = 5,
pages = {2032-2035},
timestamp = {2015-03-17T01:09:57.000+0100},
title = {Influence of potential fluctuations on Landau quantization and spin splitting studied by low temperature scanning tunneling spectroscopy on InAs(110)},
url = {http://scitation.aip.org/content/avs/journal/jvstb/20/5/10.1116/1.1506906},
volume = 20,
year = 2002
}

### 2001

1. Nb-induced two-dimensional electron gas on $n-\mathrm{InAs}(110):$ Anomalous coverage dependence Phys. Rev. B 63, 205305 (2001); doi:10.1103/PhysRevB.63.205305
@article{PhysRevB.63.205305,
author = {Getzlaff, M. and Morgenstern, M. and Meyer, Chr. and Brochier, R. and Johnson, R. L. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/2b1705e3eba46aea78b91cdf6bce9f0c0/institut2b},
description = {Phys. Rev. B 63, 205305 (2001) - Nb-induced two-dimensional electron gas on $n$-${}\mathrm{InAs}(110):$ Anomalous coverage dependence},
doi = {10.1103/PhysRevB.63.205305},
interhash = {75472f21200ec3536dd0e4e64e7c869d},
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journal = {Phys. Rev. B},
keywords = {morgenstern},
month = apr,
number = 20,
numpages = {6},
eid = {205305},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:11:02.000+0100},
title = {Nb-induced two-dimensional electron gas on $n-\mathrm{InAs}(110):$ Anomalous coverage dependence},
volume = 63,
year = 2001
}
2. Local Density of States of a Three-Dimensional Conductor in the Extreme Quantum Limit Phys. Rev. Lett. 86, 1582-1585 (2001); doi:10.1103/PhysRevLett.86.1582
@article{PhysRevLett.86.1582,
author = {Haude, D. and Morgenstern, M. and Meinel, I. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/205a61c34663b940116c89320fbb1d66d/institut2b},
description = {Phys. Rev. Lett. 86, 1582 (2001) - Local Density of States of a Three-Dimensional Conductor in the Extreme Quantum Limit},
doi = {10.1103/PhysRevLett.86.1582},
interhash = {e094187c1c88b8437e86e00321007389},
intrahash = {05a61c34663b940116c89320fbb1d66d},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = feb,
number = 8,
numpages = {0},
pages = {1582--1585},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:11:05.000+0100},
title = {Local Density of States of a Three-Dimensional Conductor in the Extreme Quantum Limit},
volume = 86,
year = 2001
}
3. Experimental evidence for edge-like states in three-dimensional electron systems Phys. Rev. B 64, 205104 (2001); doi:10.1103/PhysRevB.64.205104
@article{PhysRevB.64.205104,
author = {Morgenstern, M. and Haude, D. and Meyer, Chr. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/2468a336eedb68ff7ddbbc6d3c6f62841/institut2b},
description = {Phys. Rev. B 64, 205104 (2001) - Experimental evidence for edge-like states in three-dimensional electron systems},
doi = {10.1103/PhysRevB.64.205104},
interhash = {3897dd520eceda2521b6c81b3fa565d0},
intrahash = {468a336eedb68ff7ddbbc6d3c6f62841},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = oct,
number = 20,
numpages = {11},
eid = {205104},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:10:59.000+0100},
title = {Experimental evidence for edge-like states in three-dimensional electron systems},
volume = 64,
year = 2001
}
4. Nonlocality of the exchange interaction probed by scanning tunneling spectroscopy Phys. Rev. B 63, 201301 (2001); doi:10.1103/PhysRevB.63.201301
@article{PhysRevB.63.201301,
author = {Morgenstern, M. and Gudmundsson, V. and Dombrowski, R. and Wittneven, Chr. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/237844a1a37a71bab92230259dcc987c2/institut2b},
description = {Phys. Rev. B 63, 201301(R) (2001) - Nonlocality of the exchange interaction probed by scanning tunneling spectroscopy},
doi = {10.1103/PhysRevB.63.201301},
interhash = {61d29141e5602887bea5c2b3a786f75d},
intrahash = {37844a1a37a71bab92230259dcc987c2},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = apr,
number = 20,
numpages = {4},
eid = {201301},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:11:29.000+0100},
title = {Nonlocality of the exchange interaction probed by scanning tunneling spectroscopy},
volume = 63,
year = 2001
}
5. Erratum: Origin of Landau oscillations observed in scanning tunneling spectroscopy on \textbf \textitn -InAs(110) [Phys. Rev. B \textbf62 , 7257 (2000)] Phys. Rev. B 63, 079901 (2001); doi:10.1103/PhysRevB.63.079901
@article{PhysRevB.63.079901,
author = {Morgenstern, M. and Haude, D. and Gudmundsson, V. and Wittneven, Chr. and Dombrowski, R. and Wiesendanger, R.},
description = {Phys. Rev. B 63, 079901 (2001) - Erratum: Origin of Landau oscillations observed in scanning tunneling spectroscopy on n-InAs(110) [Phys. Rev. B 62, 7257 (2000)]},
doi = {10.1103/PhysRevB.63.079901},
interhash = {711793149948cab5d73deece1809aca3},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = jan,
number = 7,
numpages = {1},
eid = {079901},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:13:12.000+0100},
title = {Erratum: Origin of Landau oscillations observed in scanning tunneling spectroscopy on \textbf{ \textit{n} } -InAs(110) [Phys. Rev. B \textbf{62} , 7257 (2000)]},
volume = 63,
year = 2001
}

### 2000

1. Spatial Fluctuations of the Density of States in Magnetic Fields Observed with Scanning Tunneling Spectroscopy Phys. Rev. Lett. 84, 5588-5591 (2000); doi:10.1103/PhysRevLett.84.5588
@article{PhysRevLett.84.5588,
author = {Morgenstern, M. and Wittneven, Chr. and Dombrowski, R. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/2e7e9758ae0eb5724efd97b0fe23b3cb3/institut2b},
description = {Phys. Rev. Lett. 84, 5588 (2000) - Spatial Fluctuations of the Density of States in Magnetic Fields Observed with Scanning Tunneling Spectroscopy},
doi = {10.1103/PhysRevLett.84.5588},
interhash = {5ee860c6bf2ecebb24364616ef112eb0},
intrahash = {e7e9758ae0eb5724efd97b0fe23b3cb3},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = jun,
number = 24,
numpages = {0},
pages = {5588--5591},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:12:54.000+0100},
title = {Spatial Fluctuations of the Density of States in Magnetic Fields Observed with Scanning Tunneling Spectroscopy},
volume = 84,
year = 2000
}
2. Origin of Landau oscillations observed in scanning tunneling spectroscopy on \textbf \textitn -InAs(110) Phys. Rev. B 62, 7257-7263 (2000); doi:10.1103/PhysRevB.62.7257
@article{PhysRevB.62.7257,
author = {Morgenstern, M. and Haude, D. and Gudmundsson, V. and Wittneven, Chr. and Dombrowski, R. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/279cf0540204481369195e4347a05d9e7/institut2b},
description = {Phys. Rev. B 62, 7257 (2000) - Origin of Landau oscillations observed in scanning tunneling spectroscopy on n-InAs(110)},
doi = {10.1103/PhysRevB.62.7257},
interhash = {baa858810491e146de12a7fe6a3b5442},
intrahash = {79cf0540204481369195e4347a05d9e7},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = sep,
number = 11,
numpages = {0},
pages = {7257--7263},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:14:09.000+0100},
title = {Origin of Landau oscillations observed in scanning tunneling spectroscopy on \textbf{ \textit{n} } -InAs(110)},
volume = 62,
year = 2000
}
3. Low temperature scanning tunneling spectroscopy on InAs(110) Journal of Electron Spectroscopy and Related Phenomena 109, 127-145 (2000); doi:10.1016/S0368-2048(00)00112-2

We review our recent work on low temperature scanning tunneling spectroscopy (STS) in magnetic field on InAs(110). First, we describe the influence of the tip on the sample. It results in band bending at the InAs-surface, more precisely in a so called tip induced quantum dot. \{STS\} of the quantum dot states is used to reconstruct the quantum dot potential, a major requirement for all further measurements. Second, we analyze the appearance of ionized dopants in constant current images within a simple model based on the local band bending approach. Third, we show scattering states of ionized dopants at different energies appearing in normalized dI/dU-images. Comparison with calculated scattering states in the Wentzel–Kramers–Brillouin (WKB)-approximation gives good correspondance and a good estimate of the depth of individual dopants beneath the surface. Finally, we discuss the energy quantization of the unoccupied states of the tip induced quantum dot in magnetic field. The corresponding dI/dU-curves exhibit peaks attributed to the Landau quantization and the spin splitting of the quantum dot.

@article{Morgenstern2000127,
abstract = {We review our recent work on low temperature scanning tunneling spectroscopy (STS) in magnetic field on InAs(110). First, we describe the influence of the tip on the sample. It results in band bending at the InAs-surface, more precisely in a so called tip induced quantum dot. \{STS\} of the quantum dot states is used to reconstruct the quantum dot potential, a major requirement for all further measurements. Second, we analyze the appearance of ionized dopants in constant current images within a simple model based on the local band bending approach. Third, we show scattering states of ionized dopants at different energies appearing in normalized dI/dU-images. Comparison with calculated scattering states in the Wentzel–Kramers–Brillouin (WKB)-approximation gives good correspondance and a good estimate of the depth of individual dopants beneath the surface. Finally, we discuss the energy quantization of the unoccupied states of the tip induced quantum dot in magnetic field. The corresponding dI/dU-curves exhibit peaks attributed to the Landau quantization and the spin splitting of the quantum dot. },
author = {Morgenstern, M. and Haude, D. and Gudmundsson, V. and Wittneven, Chr. and Dombrowski, R. and Steinebach, Chr. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/238fea2135cefececf080ee38ed4ee2d5/institut2b},
description = {Low temperature scanning tunneling spectroscopy on InAs(110)},
doi = {10.1016/S0368-2048(00)00112-2},
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intrahash = {38fea2135cefececf080ee38ed4ee2d5},
issn = {0368-2048},
journal = {Journal of Electron Spectroscopy and Related Phenomena },
keywords = {morgenstern},
number = {1–2},
pages = {127 - 145},
timestamp = {2015-03-17T01:14:15.000+0100},
title = {Low temperature scanning tunneling spectroscopy on InAs(110) },
url = {http://www.sciencedirect.com/science/article/pii/S0368204800001122},
volume = 109,
year = 2000
}
4. Coverage dependence of the Fe-induced Fermi-level shift and the two-dimensional electron gas on InAs(110) Phys. Rev. B 61, 13805-13812 (2000); doi:10.1103/PhysRevB.61.13805
@article{PhysRevB.61.13805,
author = {Morgenstern, M. and Getzlaff, M. and Haude, D. and Wiesendanger, R. and Johnson, R. L.},
biburl = {http://www.bibsonomy.org/bibtex/231db086d7eba77bb3545ea7686a2c52d/institut2b},
description = {Phys. Rev. B 61, 13805 (2000) - Coverage dependence of the Fe-induced Fermi-level shift and the two-dimensional electron gas on InAs(110)},
doi = {10.1103/PhysRevB.61.13805},
interhash = {9e7f5ec35dc8e54ba4db3beda581228f},
intrahash = {31db086d7eba77bb3545ea7686a2c52d},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = may,
number = 20,
numpages = {0},
pages = {13805--13812},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:14:33.000+0100},
title = {Coverage dependence of the Fe-induced Fermi-level shift and the two-dimensional electron gas on InAs(110)},
volume = 61,
year = 2000
}

### 1999

1. Tip-induced band bending by scanning tunneling spectroscopy of the states of the tip-induced quantum dot on InAs(110) Phys. Rev. B 59, 8043-8048 (1999); doi:10.1103/PhysRevB.59.8043
@article{PhysRevB.59.8043,
author = {Dombrowski, R. and Steinebach, Chr. and Wittneven, Chr. and Morgenstern, M. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/21dd28b4753e831d5358b824f8bee7565/institut2b},
description = {Phys. Rev. B 59, 8043 (1999) - Tip-induced band bending by scanning tunneling spectroscopy of the states of the tip-induced quantum dot on InAs(110)},
doi = {10.1103/PhysRevB.59.8043},
interhash = {68793c43918f11241d8c04aef281bfd9},
intrahash = {1dd28b4753e831d5358b824f8bee7565},
journal = {Phys. Rev. B},
keywords = {morgenstern},
month = mar,
number = 12,
numpages = {0},
pages = {8043--8048},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:16:36.000+0100},
title = {Tip-induced band bending by scanning tunneling spectroscopy of the states of the tip-induced quantum dot on InAs(110)},
volume = 59,
year = 1999
}
2. Collective effects in the adatom production by 4.5 keV rare-gas impacts on Pt(111): A low-temperature scanning tunnelling microscopy analysis Philosophical Magazine A 79, 775-794 (1999); doi:10.1080/01418619908210331
@article{doi:10.1080/01418619908210331,
author = {Morgenstern, Markus. and Michely, Thomas. and Comsa, George.},
biburl = {http://www.bibsonomy.org/bibtex/2b318aa52667ee808b2921bc95c8b1432/institut2b},
description = {Taylor & Francis Online :: Collective effects in the adatom production by 4.5 keV rare-gas impacts on Pt(111): A low-temperature scanning tunnelling microscopy analysis - Philosophical Magazine A - Volume 79, Issue 4},
doi = {10.1080/01418619908210331},
eprint = {http://dx.doi.org/10.1080/01418619908210331},
intrahash = {b318aa52667ee808b2921bc95c8b1432},
journal = {Philosophical Magazine A},
keywords = {morgenstern},
number = 4,
pages = {775-794},
timestamp = {2015-03-17T01:16:43.000+0100},
title = {Collective effects in the adatom production by 4.5 keV rare-gas impacts on Pt(111): A low-temperature scanning tunnelling microscopy analysis},
url = {http://dx.doi.org/10.1080/01418619908210331},
volume = 79,
year = 1999
}

### 1998

1. Scanning tunneling spectroscopy on n-InAs(110): Landau-level quantization and scattering of electron waves at dopant atoms Applied Physics A 66, 203-206 (1998); doi:10.1007/s003390051130
@article{noKey111111,
author = {Dombrowski, R. and Wittneven, C. and Morgenstern, M. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/2d217fc3032143cdb488d1482aeb30bc7/institut2b},
description = {Scanning tunneling spectroscopy on n-InAs(110): Landau-level quantization and scattering of electron waves at dopant atoms - Springer},
doi = {10.1007/s003390051130},
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issn = {0947-8396},
journal = {Applied Physics A},
keywords = {morgenstern},
language = {English},
number = 1,
pages = {203-206},
publisher = {Springer-Verlag},
timestamp = {2015-03-17T01:18:04.000+0100},
title = {Scanning tunneling spectroscopy on n-InAs(110): Landau-level quantization and scattering of electron waves at dopant atoms},
url = {http://dx.doi.org/10.1007/s003390051130},
volume = 66,
year = 1998
}
2. Local Electronic Properties in the Presence of Internal and External Magnetic Fields Studied by Variable-Temperature Scanning Tunneling Spectroscopy Japanese Journal of Applied Physics 37, 3769 (1998);

We have developed a new low-temperature ultrahigh vacuum scanning tunneling microscope (UHV-STM) setup combined with a solenoid and a split-pair magnet. The STM can be operated in the 10 -11 mbar range, down to 7 K and in a rotatable magnetic field of up to 7 T perpendicular and 2 T parallel to the sample surface. This LT-UHV-STM setup was applied to study the Landau level quantization in n-type InAs(110). In addition to the observation of the Landau level splitting of the conduction band we were able to determine the energy dependence of the effective electron mass due to the nonparabolicity of the conduction band. Furthermore, we have studied the scattering of electron waves at dopant atoms located several nanometers (1–20 nm) below the surface. In a second study we have applied variable-temperature UHV-STM to investigate the temperature-dependent exchange splitting of a d z 2 -like surface state of Gd(0001) thin films. The experimental results indicate that the high spatial localization of the surface state helps to maintain a local exchange splitting even above the Curie temperature but does not result in an enhanced surface Curie temperature. Finally, we have demonstrated spin-polarized vacuum tunneling from a ferromagnetically-coated tip into the exchange-split surface state of Gd(0001).

@article{1347-4065-37-6S-3769,
abstract = {We have developed a new low-temperature ultrahigh vacuum scanning tunneling microscope (UHV-STM) setup combined with a solenoid and a split-pair magnet. The STM can be operated in the 10 -11 mbar range, down to 7 K and in a rotatable magnetic field of up to 7 T perpendicular and 2 T parallel to the sample surface. This LT-UHV-STM setup was applied to study the Landau level quantization in n-type InAs(110). In addition to the observation of the Landau level splitting of the conduction band we were able to determine the energy dependence of the effective electron mass due to the nonparabolicity of the conduction band. Furthermore, we have studied the scattering of electron waves at dopant atoms located several nanometers (1–20 nm) below the surface. In a second study we have applied variable-temperature UHV-STM to investigate the temperature-dependent exchange splitting of a d z 2 -like surface state of Gd(0001) thin films. The experimental results indicate that the high spatial localization of the surface state helps to maintain a local exchange splitting even above the Curie temperature but does not result in an enhanced surface Curie temperature. Finally, we have demonstrated spin-polarized vacuum tunneling from a ferromagnetically-coated tip into the exchange-split surface state of Gd(0001).},
author = {Wiesendanger, Roland and Bode, Matthias and Dombrowski, Ralph and Getzlaff, Mathias and Morgenstern, Markus and Wittneven, Christian},
biburl = {http://www.bibsonomy.org/bibtex/201bc3d85055f90e84e87b03a5ed9c101/institut2b},
description = {Local Electronic Properties in the Presence of Internal and External Magnetic Fields Studied by Variable-Temperature Scanning Tunneling Spectroscopy - Abstract - Japanese Journal of Applied Physics - IOPscience},
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timestamp = {2015-03-17T01:18:07.000+0100},
title = {Local Electronic Properties in the Presence of Internal and External Magnetic Fields Studied by Variable-Temperature Scanning Tunneling Spectroscopy},
url = {http://stacks.iop.org/1347-4065/37/i=6S/a=3769},
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}
3. Tieftemperatur-Rastertunnelspektroskopie an InAs(110): Streuung von Elektronenwellen an Dotieratomen und Spektroskopie an Landau-Niveaus Physik Journal 54, 423-426 (1998); doi:10.1002/phbl.19980540509

Das Rastertunnelmikroskop (RTM) kann nicht nur zur Vermessung der Oberflächentopographie bis hinab zur atomaren Skala eingesetzt werden, sondern es ermöglicht im Spektroskopiemodus auch, die räumliche Verteilung von elektronischen Zustandsdichten zu bestimmen. Tiefe Temperaturen (T < 10 K) erlauben Energieauflösungen im meV-Bereich. Dadurch läßt sich eine Zustandsquantisierung, wie sie zum Beispiel in nulldimensionalen Quantentöpfen oder als Landau-Quantisierung im Magnetfeld auftritt, sichtbar machen. Am Institut für Angewandte Physik der Universität Hamburg existiert seit kurzem eine Anlage, die erstmalig Rastertunnelmikroskopie, tiefe Temperaturen (8 K), Magnetfeld (0–6,5 T) und Ultrahochvakuum kombiniert [1]. Mit dieser Anlage wurde an der Halbleiter-Oberfläche InAs(110) die Streuung von energieselektierten Elektronen an einzelnen Dotieratomen studiert und die Landau-Niveauaufspaltung im Magnetfeld spektroskopiert.

@article{PHBL:PHBL19980540509,
abstract = {Das Rastertunnelmikroskop (RTM) kann nicht nur zur Vermessung der Oberflächentopographie bis hinab zur atomaren Skala eingesetzt werden, sondern es ermöglicht im Spektroskopiemodus auch, die räumliche Verteilung von elektronischen Zustandsdichten zu bestimmen. Tiefe Temperaturen (T < 10 K) erlauben Energieauflösungen im meV-Bereich. Dadurch läßt sich eine Zustandsquantisierung, wie sie zum Beispiel in nulldimensionalen Quantentöpfen oder als Landau-Quantisierung im Magnetfeld auftritt, sichtbar machen. Am Institut für Angewandte Physik der Universität Hamburg existiert seit kurzem eine Anlage, die erstmalig Rastertunnelmikroskopie, tiefe Temperaturen (8 K), Magnetfeld (0–6,5 T) und Ultrahochvakuum kombiniert [1]. Mit dieser Anlage wurde an der Halbleiter-Oberfläche InAs(110) die Streuung von energieselektierten Elektronen an einzelnen Dotieratomen studiert und die Landau-Niveauaufspaltung im Magnetfeld spektroskopiert.},
author = {Morgenstern, M. and Dombrowski, R. and Wittneven, Chr. and Wiesendanger, R.},
description = {Tieftemperatur-Rastertunnelspektroskopie an InAs(110): Streuung von Elektronenwellen an Dotieratomen und Spektroskopie an Landau-Niveaus - Morgenstern - 2013 - Physikalische Blätter - Wiley Online Library},
doi = {10.1002/phbl.19980540509},
issn = {1521-3722},
journal = {Physik Journal},
keywords = {morgenstern},
number = 5,
pages = {423--426},
publisher = {WILEY-VCH Verlag GmbH},
timestamp = {2015-03-17T01:18:10.000+0100},
title = {Tieftemperatur-Rastertunnelspektroskopie an InAs(110): Streuung von Elektronenwellen an Dotieratomen und Spektroskopie an Landau-Niveaus},
url = {http://dx.doi.org/10.1002/phbl.19980540509},
volume = 54,
year = 1998
}
4. Landau Level Quantization Measured by Scanning Tunneling Spectroscopy on n-InAs(110) physica status solidi (b) 210, 845-851 (1998); doi:10.1002/%28SICI%291521-3951%28199812%29210%3A2%3C845%3A%3AAID-PSSB845%3E3.0.CO%3B2-9

The in-situ cleaved n-InAs(110) surface is studied by low temperature scanning tunneling spectroscopy and microscopy in magnetic fields up to 6 T perpendicular to the surface. The dI/dV(V) curves exhibit characteristic oscillations in magnetic field, which are attributed to Landau levels in the conduction band. The energy dependence of the effective electron mass is determined. Dopants reduce the Landau level energy. As expected, the energy reduction decreases with increasing Landau level number.

@article{PSSB:PSSB845,
abstract = {The in-situ cleaved n-InAs(110) surface is studied by low temperature scanning tunneling spectroscopy and microscopy in magnetic fields up to 6 T perpendicular to the surface. The dI/dV(V) curves exhibit characteristic oscillations in magnetic field, which are attributed to Landau levels in the conduction band. The energy dependence of the effective electron mass is determined. Dopants reduce the Landau level energy. As expected, the energy reduction decreases with increasing Landau level number.},
author = {Morgenstern, M. and Dombrowski, R. and Wittneven, Chr. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/2e7ee220e485f8b81a20a7642a6335291/institut2b},
description = {Landau Level Quantization Measured by Scanning Tunneling Spectroscopy on n-InAs(110) - Morgenstern - 1999 - physica status solidi (b) - Wiley Online Library},
doi = {10.1002/%28SICI%291521-3951%28199812%29210%3A2%3C845%3A%3AAID-PSSB845%3E3.0.CO%3B2-9},
interhash = {e0a05e50a4494c5d87b354d5e9885197},
intrahash = {e7ee220e485f8b81a20a7642a6335291},
issn = {1521-3951},
journal = {physica status solidi (b)},
keywords = {morgenstern},
number = 2,
pages = {845--851},
publisher = {WILEY-VCH Verlag},
timestamp = {2015-03-17T01:18:14.000+0100},
title = {Landau Level Quantization Measured by Scanning Tunneling Spectroscopy on n-InAs(110)},
url = {http://dx.doi.org/10.1002/%28SICI%291521-3951%28199812%29210%3A2%3C845%3A%3AAID-PSSB845%3E3.0.CO%3B2-9},
volume = 210,
year = 1998
}
5. Scattering States of Ionized Dopants Probed by Low Temperature Scanning Tunneling Spectroscopy Phys. Rev. Lett. 81, 5616-5619 (1998); doi:10.1103/PhysRevLett.81.5616
@article{PhysRevLett.81.5616,
author = {Wittneven, Chr. and Dombrowski, R. and Morgenstern, M. and Wiesendanger, R.},
biburl = {http://www.bibsonomy.org/bibtex/24e586d46331f1ff0fe60df06399596ab/institut2b},
description = {Phys. Rev. Lett. 81, 5616 (1998) - Scattering States of Ionized Dopants Probed by Low Temperature Scanning Tunneling Spectroscopy},
doi = {10.1103/PhysRevLett.81.5616},
interhash = {ec3016281ed6404e3a8f17d2575fe257},
intrahash = {4e586d46331f1ff0fe60df06399596ab},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = dec,
number = 25,
numpages = {0},
pages = {5616--5619},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:18:16.000+0100},
title = {Scattering States of Ionized Dopants Probed by Low Temperature Scanning Tunneling Spectroscopy},
volume = 81,
year = 1998
}

### 1997

1. Onset of Interstitial Diffusion Determined by Scanning Tunneling Microscopy Phys. Rev. Lett. 79, 1305-1308 (1997); doi:10.1103/PhysRevLett.79.1305
@article{PhysRevLett.79.1305,
author = {Morgenstern, Markus and Michely, Thomas and Comsa, George},
biburl = {http://www.bibsonomy.org/bibtex/2c92c63eb5bd03c13c455c63ba176e18c/institut2b},
description = {Phys. Rev. Lett. 79, 1305 (1997) - Onset of Interstitial Diffusion Determined by Scanning Tunneling Microscopy},
doi = {10.1103/PhysRevLett.79.1305},
interhash = {000b2b661029fb62f3d03f163cb89c90},
intrahash = {c92c63eb5bd03c13c455c63ba176e18c},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = aug,
number = 7,
numpages = {0},
pages = {1305--1308},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:20:07.000+0100},
title = {Onset of Interstitial Diffusion Determined by Scanning Tunneling Microscopy},
volume = 79,
year = 1997
}
2. Effect of energetic particles on island formation in sputter deposition of Pt on Pt(111) Applied Physics Letters 70, 182-184 (1997); doi:10.1063/1.118351

During ion beamsputter deposition besides the deposited atoms, which reach the substrate with kinetic energies in the 10 eV range, a certain amount of energetic particles also hit the substrate. These particles which have been reflected or sputtered at the target represent only a small fraction of the atoms reaching the substrate, but have energies of the order of the sputteringbeam. The influence of these particles on the island formation of Pt films on a Pt(111) surface has been examined by variation of the deposition geometry, the primary ion energy, and the substrate temperature. It is demonstrated that the main effect is a dramatic increase in island density. The experimental results are in quantitative agreement with the results of a newly developed computer code.

@article{:/content/aip/journal/apl/70/2/10.1063/1.118351,
abstract = {During ion beamsputter deposition besides the deposited atoms, which reach the substrate with kinetic energies in the 10 eV range, a certain amount of energetic particles also hit the substrate. These particles which have been reflected or sputtered at the target represent only a small fraction of the atoms reaching the substrate, but have energies of the order of the sputteringbeam. The influence of these particles on the island formation of Pt films on a Pt(111) surface has been examined by variation of the deposition geometry, the primary ion energy, and the substrate temperature. It is demonstrated that the main effect is a dramatic increase in island density. The experimental results are in quantitative agreement with the results of a newly developed computer code.},
author = {Kalff, Matthias and Breeman, Marinus and Morgenstern, Markus and Michely, Thomas and Comsa, George},
biburl = {http://www.bibsonomy.org/bibtex/2d82e9836cdfa094ae80d9f4a1ef78169/institut2b},
description = {Effect of energetic particles on island formation in sputter deposition of Pt on Pt(111)},
doi = {10.1063/1.118351},
interhash = {c40cabb3dcb93c83019a2f327492c6f6},
intrahash = {d82e9836cdfa094ae80d9f4a1ef78169},
journal = {Applied Physics Letters},
keywords = {morgenstern},
number = 2,
pages = {182-184},
timestamp = {2015-03-17T01:20:15.000+0100},
title = {Effect of energetic particles on island formation in sputter deposition of Pt on Pt(111)},
url = {http://scitation.aip.org/content/aip/journal/apl/70/2/10.1063/1.118351},
volume = 70,
year = 1997
}

### 1996

1. New Approach for Determination of Diffusion Parameters of Adatoms Phys. Rev. Lett. 76, 1304-1307 (1996); doi:10.1103/PhysRevLett.76.1304
@article{PhysRevLett.76.1304,
author = {Bott, Michael and Hohage, Michael and Morgenstern, Markus and Michely, Thomas and Comsa, George},
biburl = {http://www.bibsonomy.org/bibtex/2c956bcd8386ca94accb6999d0ffe886d/institut2b},
description = {Phys. Rev. Lett. 76, 1304 (1996) - New Approach for Determination of Diffusion Parameters of Adatoms},
doi = {10.1103/PhysRevLett.76.1304},
interhash = {374cdc6ff3a85c1675b9e57c3a238e82},
intrahash = {c956bcd8386ca94accb6999d0ffe886d},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = feb,
number = 8,
numpages = {0},
pages = {1304--1307},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:20:28.000+0100},
title = {New Approach for Determination of Diffusion Parameters of Adatoms},
volume = 76,
year = 1996
}
2. Atomic Processes in Low Temperature Pt-Dendrite Growth on Pt(111) Phys. Rev. Lett. 76, 2366-2369 (1996); doi:10.1103/PhysRevLett.76.2366
@article{PhysRevLett.76.2366,
author = {Hohage, Michael and Bott, Michael and Morgenstern, Markus and Zhang, Zhenyu and Michely, Thomas and Comsa, George},
biburl = {http://www.bibsonomy.org/bibtex/208af76d0d6b733ed06ff1c1cc16e84b5/institut2b},
description = {Phys. Rev. Lett. 76, 2366 (1996) - Atomic Processes in Low Temperature Pt-Dendrite Growth on Pt(111)},
doi = {10.1103/PhysRevLett.76.2366},
interhash = {321b3789e8de7c8016efe6021c33c2b9},
intrahash = {08af76d0d6b733ed06ff1c1cc16e84b5},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = mar,
number = 13,
numpages = {0},
pages = {2366--2369},
publisher = {American Physical Society},
timestamp = {2015-03-17T01:20:31.000+0100},
title = {Atomic Processes in Low Temperature Pt-Dendrite Growth on Pt(111)},
volume = 76,
year = 1996
}
3. Nucleation and morphology of homoepitaxial Pt(111)-films grown with ion beam assisted deposition Surface Science 365, 187-204 (1996); doi:10.1016/0039-6028(96)00744-3

The nucleation and morphology of thin Pt-films grown with ion beam assisted deposition (IBAD) on Pt(111) have been studied by scanning tunneling microscopy and low energy electron diffraction. In comparison to conventional vapor phase deposition it is found that the simultaneous ion bombardment with Ar+ (400eV)- and Ar+ (4keV)-ions during deposition drastically increases the island number density at T=200 K. The increase is due to nucleation at ion impact induced adatom clusters. As a consequence of the increased island number density, the lateral dimensions of the film microstructure are decreased. In contrast, at T=70 K where the adatom diffusion is thermally inhibited the simultaneous ion bombardment leads to a decreased island number density due to ion impact induced adatom mobility. Thin Pt-films grown with ion assistance at T = 50 K exhibit an improved epitaxy compared to the rather amorphous Pt-films grown by conventional vapor phase deposition at this temperature.

@article{Esch1996187,
abstract = {The nucleation and morphology of thin Pt-films grown with ion beam assisted deposition (IBAD) on Pt(111) have been studied by scanning tunneling microscopy and low energy electron diffraction. In comparison to conventional vapor phase deposition it is found that the simultaneous ion bombardment with Ar+ (400eV)- and Ar+ (4keV)-ions during deposition drastically increases the island number density at T=200 K. The increase is due to nucleation at ion impact induced adatom clusters. As a consequence of the increased island number density, the lateral dimensions of the film microstructure are decreased. In contrast, at T=70 K where the adatom diffusion is thermally inhibited the simultaneous ion bombardment leads to a decreased island number density due to ion impact induced adatom mobility. Thin Pt-films grown with ion assistance at T = 50 K exhibit an improved epitaxy compared to the rather amorphous Pt-films grown by conventional vapor phase deposition at this temperature. },
author = {Esch, Stefanie and Breeman, Marinus and Morgenstern, Markus and Michely, Thomas and Comsa, George},
biburl = {http://www.bibsonomy.org/bibtex/24c4e10fcaaab852eeb0c0e4efac0319d/institut2b},
description = {Nucleation and morphology of homoepitaxial Pt(111)-films grown with ion beam assisted deposition},
doi = {10.1016/0039-6028(96)00744-3},
interhash = {afc5cee5c68ed77505a13182d1b2f077},
intrahash = {4c4e10fcaaab852eeb0c0e4efac0319d},
issn = {0039-6028},
journal = {Surface Science },
keywords = {morgenstern},
number = 2,
pages = {187 - 204},
timestamp = {2015-03-17T01:20:34.000+0100},
title = {Nucleation and morphology of homoepitaxial Pt(111)-films grown with ion beam assisted deposition },
url = {http://www.sciencedirect.com/science/article/pii/0039602896007443},
volume = 365,
year = 1996
}
4. Anisotropy in the Adsorption of ${\mathrm{H}}_{2}$O at Low Coordination Sites on Pt(111) Phys. Rev. Lett. 77, 703-706 (1996); doi:10.1103/PhysRevLett.77.703
@article{PhysRevLett.77.703,
author = {Morgenstern, Markus and Michely, Thomas and Comsa, George},
biburl = {http://www.bibsonomy.org/bibtex/22e13da6fa70ccf5539fffc66e5bb4d6f/institut2b},
description = {Phys. Rev. Lett. 77, 703 (1996) - Anisotropy in the Adsorption of ${\mathrm{H}}_{2}$O at Low Coordination Sites on Pt(111)},
doi = {10.1103/PhysRevLett.77.703},
interhash = {3b44914a53468052eabf0e822137c141},
intrahash = {2e13da6fa70ccf5539fffc66e5bb4d6f},
journal = {Phys. Rev. Lett.},
keywords = {morgenstern},
month = jul,
number = 4,
numpages = {0},
pages = {703--706},
publisher = {American Physical Society},
timestamp = {2015-03-17T14:52:21.000+0100},
title = {Anisotropy in the Adsorption of ${\mathrm{H}}_{2}$O at Low Coordination Sites on Pt(111)},
volume = 77,
year = 1996
}

### 1994

1. On the structure and electronic properties of the GaAs(113¯)B surface Surface Science 316, 157-167 (1994); doi:10.1016/0039-6028(94)91136-3

GaAs(113¯)B surfaces were prepared by ion bombardment and annealing (IBA) and by molecular beam epitaxy (MBE) using a single Knudsen cell filled with GaAs. These surfaces were investigated through low-energy electron diffraction (LEED), Auger electron spectroscopy (AES) and angle-resolved \{UV\} photoelectron spectroscopy (ARUPS) using photon energies of hv = 11.8 and 21.2 eV and synchrotron light. With both \{IBA\} and MBE, a 1 × 1 reconstructed surface was prepared which differs by a large amount of As in the surface layer. For the \{MBE\} 1 × 1 reconstructed surface, three different surface states or resonances were found at +0.3, -0.7 and -3.5 eV with respect to the valence band maximum which are assigned to As-derived dangling bonds and back bonds. The states at + 0.3 and -0.7 eV can be quenched by H adsorption. For the n-type sample the bands are bent upwards by 0.30 V at the surface.

@article{Scholz1994157,
abstract = {GaAs(113¯)B surfaces were prepared by ion bombardment and annealing (IBA) and by molecular beam epitaxy (MBE) using a single Knudsen cell filled with GaAs. These surfaces were investigated through low-energy electron diffraction (LEED), Auger electron spectroscopy (AES) and angle-resolved \{UV\} photoelectron spectroscopy (ARUPS) using photon energies of hv = 11.8 and 21.2 eV and synchrotron light. With both \{IBA\} and MBE, a 1 × 1 reconstructed surface was prepared which differs by a large amount of As in the surface layer. For the \{MBE\} 1 × 1 reconstructed surface, three different surface states or resonances were found at +0.3, -0.7 and -3.5 eV with respect to the valence band maximum which are assigned to As-derived dangling bonds and back bonds. The states at + 0.3 and -0.7 eV can be quenched by H adsorption. For the n-type sample the bands are bent upwards by 0.30 V at the surface. },
author = {Scholz, S.M. and Morgenstern, M. and Jacobi, K.},
biburl = {http://www.bibsonomy.org/bibtex/221971e36d8180128aa59c49a6ea855a9/institut2b},
description = {On the structure and electronic properties of the GaAs(113¯)B surface},
doi = {10.1016/0039-6028(94)91136-3},
interhash = {9f7821aedd290de10101a5c51fe87593},
intrahash = {21971e36d8180128aa59c49a6ea855a9},
issn = {0039-6028},
journal = {Surface Science },
keywords = {morgenstern},
number = {1–2},
pages = {157 - 167},
timestamp = {2015-03-17T01:21:22.000+0100},
title = {On the structure and electronic properties of the GaAs(113¯)B surface },
url = {http://www.sciencedirect.com/science/article/pii/0039602894911363},
volume = 316,
year = 1994
}