Dresden 2011 – scientific programme

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HL: Fachverband Halbleiterphysik

HL 33: Spin-dependent Transport I

HL 33.8: Talk

Tuesday, March 15, 2011, 12:15–12:30, POT 251

Magnetogyrotropic photogalvanic effects in InSb-based quantum wells — •Sebastian Stachel¹, Cynthia Karl¹, Thomas Stangl¹, Peter Olbrich¹, Vasily Bel’kov², Steven K. Clowes³, Tim Ashley⁴, and Sergey D. Ganichev¹ — ¹Terahertz Center, University of Regensburg, Regensburg, Germany — ²Ioffe Institute, St. Petersburg, Russia — ³Advanced Technology Institute, University of Surrey, UK — ⁴QinetiQ, Malvern, UK

We report on the observation of the magnetic-field induced photocurrent in n-doped InSb/InAlSb quantum wells (QWs) excited by terahertz radiation. The photocurrent behavior upon variation of the radiation polarization, magnetic field strength, B, and temperature is studied. While at a moderate magnetic field the photocurrent exhibits a linear field dependence, at high magnetic fields it becomes nonlinear and even changes its sign. The experimental results are analyzed in terms of the magneto-gyrotropic photogalvanic effect (MPGE) based on the asymmetry of optical transitions and/or asymmetric relaxation of carriers in the momentum space [1]. We demonstrate that the sign inversion of the photocurrent is caused by the interplay of two mechanisms: The spin mechanism, which yields a saturation of the current at high magnetic fields due to the large Zeeman splitting in InSb-based QWs, and the orbital mechanism, which depends linearly on B and has an opposite sign. The latter contribution dominates the total current at high magnetic fields.

[1] V.V. Belkov and S.D. Ganichev, Sem. Sci. Tec. 23, 114003 (2008)