Regensburg 2013 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 58: Poster Session III (Solid-liquid interfaces; Scanning probe and other methods; Electronic structure theory; Spin-orbit interaction)
O 58.40: Poster
Mittwoch, 13. März 2013, 18:15–21:45, Poster B1
Surface investigation of Topological Insulators with STM and STS: From local defects and aging processes. — •Sebastian Fiedler1,2, Peter Lutz1,2, Henriette Maas1,2, Christoph Seibel1,2, Hendrik Bentmann1,2, and Friedrich Reinert1,2 — 1Experimentelle Physik VII, Universität Würzburg, 97074 Würzburg, Germany — 2Gemeinschaftslabor für Nanoanalytik, Karlsruher Institute für Technologie KIT, 76021 Karlsruhe, Germany
Topological Insulators (TIs) are presently one of the most promising topics in solid state physics. Theoretical calculations predict a spin polarised current on the surface of the TI without electrical resistance, which should be robust since the involved states are protected by time reversal symmetry. This dissipation-less transport of a spin polarised current requires an insulating bulk and a band gap with two crossing bands, one for spin up and one for spin down states [1]. However, defects are the main reason, why the bulk is not insulating thus destroying this effect. We investigate the surface of TIs with Scanning Tunnelling Microscopy (STM) and Spectroscopy (STS). We observe local defects and measure the local electron density, which helps understanding the influence of defects. Moreover, we demonstrate that aging of the TI results in a broadening of the band gap. This effect can also be mimicked by adsorption of alkali metals.
[1] arXiv:0801.0901v1 [cond-mat.mes-hall] 7 Jan 2008