Topological Insulators

  Copyright: © Marco Pratzer Scanning tunneling microscopy and spectroscopy image of an electron channel at the step edge of a weak topological insulator.

Topological insulators exhibit surface states which are protected by the symmetry of the insulating bulk. They cannot be detroyed by local defects at the surface. We investigate weak topological insulators which provide conducting edge states at the surface. Additionally, we probe whether phase change materials (that can be switched between crystalline and amorphous on a ns time scale) are also topological insulators in their crystalline phase. Furthermore, we prepare interfaces which potentially host Majorana fermions. These investigations are related to quantum Hall systems which also contain topologically protected states.

Central goal is the imaging of topological properties on a local scale.

Methods

• Angle-resolved photoemission spectroscopy (ARPES) with spin-resolution

• Scanning tunneling microscopy (STM) and spectroscopy (STS)