Analysis of the Local Electrochemical Potential of Current Carrying Topological Insulating Surfaces

• Applicant: Dr. Christian A. Bobisch
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2014 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 259199719

This project focusses on the analysis of electronic transport at the surface of a topological insulator (TI) on a local scale by means of scanning tunneling potentiometry (STP). When a lateral current is flowing through the surface, scattering at a defect leads to a change of the local electrochemical potential µec. Hence, the analysis of the latter will reveal details of the scattering processes, e.g. howfar they are suppressed due to the conservation of the spin. Using a multiprobe scanning tunneling microscope (STM) the influence of different kinds of surface defects, e.g. atomic steps, domain boundaries, point defects, adsorbates etc. to µec shall be studied by STP.The STP measurements shall be performed on both, bulk TI material and epitaxial thin films grown on low conducting substrates (Silicon). The bulk material TI (Bi2Se3 and Bi2Te3) is commercially available while the growth of epitaxial Bi2Se3 and Bi2Te3 films can be performed in-situ before performing the STP experiments. The analysis of µec in the vicinity of various magnetic and non-magnetic defects will help to elucidate the physical origins behind the observed local potential variation. The evaluation of thin TI films vs. bulk material may give further prospect for the use of TI in real electronic devices on supporting substrates.

• DFG Programme: Research Grants
• International Connection: USA
• Participating Persons: Professor Wilson Ho, Ph.D.; Professor Dr. Rolf Möller; Professor Dr. Hermann Nienhaus