Regensburg 2016 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 35: Poster I

HL 35.18: Poster

Tuesday, March 8, 2016, 15:00–19:00, Poster A

Terahertz radiation induced photocurrents in (Bi_1−xSb_x)₂Te₃ based topological insulators — •Helene Plank¹, Leonid E. Golub², Stefan Bauer¹, Vasily V. Bel’kov², Markus Eschbach³, Lukasz Plucinski³, Gregor Mussler³, Detlev Grützmacher³, and Sergey. D. Ganichev¹ — ¹Terahertz Center, University of Regensburg, Regensburg, Germany — ²Ioffe Physical-Technical Institute, St. Petersburg, Russia — ³Jülich Aachen Research Alliance (JARA-FIT), Jülich, Germany

Here we report on the observation of terahertz (THz) laser radiation induced photocurrents in epitaxially grown (Bi_1−xSb_x)₂Te₃ three dimensional topological insulators with antimony concentrations x varying from 0 (n-type) to 1 (p-type conductivity). At normal incidence the photocurrent is dominated by the photogalvanic effect (PGE). It is allowed in the surface states only due to a "symmetry filtration" [1]. However, at oblique incidence the PGE diminishes and a photon drag effect, arising in the trigonal symmetry of the samples due to an in-plane component of the photon momentum, is dominating the photocurrent formation at certain frequencies. We show that this trigonal PDE results in a photocurrent even in the angle of incidence θ and that it is caused by the in-plane gradient of the radiation electric field accompanied by asymmetric elastic scattering. [1] P. Olbrich et al., Phys. Rev. Lett. 113, 096601(2014)