Dresden 2017 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 70: Topological Insulators I (joined session with TT)

HL 70.5: Vortrag

Donnerstag, 23. März 2017, 10:45–11:00, POT 251

Anisotropy of Magneto-Transport on the Surface of Topological Insulators — •Alexey Taskin¹, Henry Legg², Fan Yang¹, Andrea Bliesener¹, Satoshi Sasaki³, Yasushi Kanai³, Kazuhiko Matsumoto³, Achim Rosch², and Yoichi Ando¹ — ¹Institute of Physics II, University of Cologne — ²Institute for Theoretical Physics, University of Cologne — ³Scientific and Industrial Research, Osaka University

Recent advances in MBE growth and microfabrication technique allow to obtain Topological Insulator (TI) systems where the transport is dominated by the surface. Here we report a magneto-transport study of high-quality bulk-insulating Bi_2−xSb_xTe₃ thin films, which were fabricated into devices with electrostatic gates on both bottom and top surfaces. For magnetic fields applied parallel to the surface of a TI, we found a clear anisotropy in magnetoresistance and related planar Hall effect that originates from the fundamental property of the surface Dirac fermions, the locking of their spin and momentum. The key signature of anisotropic magnetoresistance is a strong dependence on the gate voltage with a characteristic two-peak structure near the Dirac point. The observed anisotropy is related to a modification of the topological protection of the Dirac electrons against backscattering from impurities in the in-plane magnetic field and provides an example of a controllable time-reversal breaking on the surface of TIs.