SKM 2021 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 25: Poster Session: Topology
TT 25.1: Poster
Donnerstag, 30. September 2021, 13:30–16:00, P
Boosting the surface conduction in a topological insulator — •Mathieu Taupin1, Gaku Eguchi1, Monika Budnovski1, Andreas Steiger-Thirsfeld2, Yukiaki Ichida3, Kenta Kuroda3,4, Shik Shin3, Akio Kimura4, and Silke Paschen1 — 1Institute of Solid State Physics, TU Wien, Austria — 2USTEM, TU Wien, Austria — 3ISSP, The University of Tokyo, Japan — 4Graduate School of Advanced Science and Engineering, Hiroshima University, Japan
Despite the intense research on topological insulators, manipulating the surface states by the application of external stimuli is surprisingly only little explored. For instance, some topological insulators have been shown to have an anomalous response when exposed to light, i.e. slow with non-exponential behaviour. These results hint on the tunability of the Dirac states with illumination, but the lack of consensus of the microscopic mechanism impedes progress.
Our work provides an understanding of these effects. We demonstrate that under external excitation (such as thermal radiation, light illumination and current driving), excited electrons will migrate to the surface states and remain there ``permanently'' due to the intrinsic Schottky barrier and space-charge separation between the surface and bulk carriers. This leads to a significant boost of the surface conduction, even in a bulk sample, which can be adjusted with the amplitude of the external excitation. We find striking similarities between our results and previous spectroscopic studies and propose a common mechanism, which is in principle applicable in any topological insulators.