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Dresden 2017 – wissenschaftliches Programm

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MA: Fachverband Magnetismus

MA 63: Topological Insulators III (joined session with TT)

MA 63.8: Vortrag

Freitag, 24. März 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. Ganichev11Terahertz 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.

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