SKM 2023 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 87: Focus Session: Scanning Probe Microscopy with Quartz Sensors III

O 87.7: Vortrag

Donnerstag, 30. März 2023, 17:00–17:15, TRE Ma

Fe adsorbates and their effect on the surfaces of topological insulators TlBiSe2 and Bi2Se3 — •Adrian Weindl, Christoph Setescak, Emma Grasser, Alexander Liebig, and Franz J. Giessibl — University of Regensburg, 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 combined scanning tunneling microscopy (STM) and atomic force microscopy (AFM). Two archetypical TIs, Bi2Se3 and TlBiSe2, are analyzed, which both have relatively large band gaps with their Dirac points well isolated and far from bulk states. 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 scanning tunneling spectroscopy. We detect resonances in the LDOS for both surfaces 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 atomically-resolved AFM measurements. In addition, we detect a relaxation of surface atoms due to the presence of Fe adatoms on Bi2Se3. The charge state of the Fe adatoms is determined by Kelvin probe force spectroscopy.