Dresden 2017 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 83: Topological Insulators III (joint session DS, HL, MA, O, TT, organized by HL)

TT 83.8: Talk

Friday, March 24, 2017, 11:45–12:00, POT 251

Probing topological edge states in HgTe-based quantum wells by terahertz photogalvanic spectroscopy — •Kathrin-Maria Dantscher¹, Dimitry A. Kozlov², Maria-Theresia Scherr¹, Sebastian Gebert¹, Jan Bärenfänger¹, Mikhail Durnev³, Sergey A. Tarasenko³, Vasily V. Bel'kov³, Nikolay N. Mikhailov², Sergey A. Dovertsky², Ze Dong Kvon², Dieter Weiss¹, and Sergey D. Ganichev¹ — ¹Terahertz Center, University of Regensburg, Regensburg, Germany — ²A.V. Rzhanov Institute of Semiconductor Physics, Novosibirsk 630090, Russia — ³Ioffe Institute, St.Petersburg, Russia

We report on the observation of a chiral photogalvanic current excited by terahertz laser radiation in the edge channels of HgTe-based 2D topological insulators (TI). The direction of the edge photocurrent reverses by switching the radiation polarization from the right- to left-handed one and, for fixed helicity, has opposite direction for opposite edges. The chiral edge photocurrent is detected in a wide range of gate voltages and reverse the sign twice upon variation of the gate voltage. We show that the data reveal that in the TI-regime the photocurrent is caused by photoionization of helical edge electrons to the conduction band, discuss the microscopic model of this phenomena and present the developed microscopic theory.