Regensburg 2022 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 21: Poster Monday: Topology and Symmetry-Protected Materials

O 21.3: Poster

Montag, 5. September 2022, 18:00–20:00, P4

Characterisation of Fe adsorbates and their effect on the local density of states on topological insulators TlBiSe2 and Bi2Se3 by means of combined STM/STS and AFM — •Adrian Weindl, Christoph Setescak, Alexander Liebig, and Franz J. Giessibl — University of Regensburg, Germany

Can one tailor the properties of the topological surface state (TSS) of topological insulators (TIs) by magnetic doping of the TI material? Here, we study the effect of magnetic adatoms on TI surfaces by means of combined scanning tunneling microscopy (STM) and atomic force microscopy (AFM). Two archetypical TIs, Bi2Se3 and TlBiSe2, are studied, which both have relatively large band gaps with their Dirac points well isolated and far from bulk states. While the surface of Bi2Se3 is atomically flat, TlBiSe2 exhibits a peculiar surface termination consisting of half a monolayer of thallium atoms sitting on top of a full selenium layer. Magnetic impurities, in this case single Fe adatoms, and their influence on the local density of states (LDOS) of the two TIs are investigated by means of scanning tunneling spectroscopy. We detect resonances in the LDOS for the Fe adatoms that arise due to the scattering of electrons in the TSS at these impurities. The position and shape of these resonances are a function of the exact adsorption position of the adatoms, which can be determined by means of atomically-resolved AFM measurements.