Low-Temperature AFM/STM System (380mK/14T)

  300mK scanning tunnelng microscopy system Copyright: © Marco Pratzer Low temperature STM system. The brown cylinder is the 380mK cryostat.

Our ultra high vacuum AFM/STM system allows measurements at 380mK and within magnetic fields up to 14T. The field can be applied perpendicular to the sample surface. For this purpose, a home-built combination of a scanning tunneling microsope and a scanning force microscope (AFM/STM) equipped with a qplus sensor is placed in the center of a superconducting coil within a cryostat . The coils are cooled by liquid helium (4.2K). The microscope is cooled by helium-3, a rare helium isotope, down to 0.38 K.

  Ultra high vacuum chambers of the 300mK sytem Copyright: © Marco Pratzer Ultra high vacuum chambers for the sample preparation and characterization.

Proben und Spitzen für das Rastertunnelmikroskop können in zwei separaten Ultrahochvakuum-Kammern der Anlage präpariert und voruntersucht werden. Hierfür stehen MBE-Verdampfer, Argon-Sputterkanone, eine LEED/Auger-Einheit sowie Probenheizungen zur Verfügung. Da das Rastertunnelmikroskop extrem vibrationsempfindlich ist, befindet sich die gesamte Anlage mit starrem Rahmen und einem Gewicht von etwa 2,5 Tonnen auf vier Luft-gepolsterten Füßen in einem eigenen Schallschutzraum.

  Homebuit AFM/STM Copyright: © Marco Pratzer Combined low temperature scanning force and scanning tunneling microscope.

The combined scanning force/scanning tunneling microscope (AFM/STM) equipped with a quartz tuning fork has been built in our group. The qPlus sensor is mounted on a xy positioning stage with a range of 2×2 mm. The sensor can be exchanged in-situ. The sample holder is mounted on the scanner piezo and addionally features a separate gate contact. The combination of AFM and STM allows a navigation towards nano-structured samples prepared on insulating substrates (like, e.g., graphene on SiO2).