Dresden 2011 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 33: Spin-dependent Transport I
HL 33.7: Talk
Tuesday, March 15, 2011, 12:00–12:15, POT 251
Spin and orbital mechanisms of the magneto-gyrotropic photogalvanic effect in GaAs/AlGaAs quantum wells — •V. Lechner1, L.E. Golub2, F. Lomakina1, V.V. Bel’kov2, P. Olbrich1, S. Stachel1, I. Caspers1, M. Griesbeck1, M. Kugler1, M.J. Hirmer1, T. Korn1, C. Schüller1, D. Schuh1, W. Wegscheider3, and S.D. Ganichev1 — 1University of Regensburg, Germany — 2Ioffe Institute, St. Petersburg, Russia — 3ETH Zurich, Switzerland
Here we report on experiments, which allow us to distinguish unambiguously between the spin-dependent [1] and most recently proposed orbital origin [2] of the THz radiation induced magneto-gyrotropic photogalvanic effect (MPGE). To achieve this goal we utilize the qualitative difference in their behavior upon a variation of the g* factor: In contrast to the orbital effects, the MPGE resulting from the spin-related roots is proportional to the Zeeman spin splitting. To explore this difference, we utilize the fact that in GaAs/AlGaAs QWs the Zeeman splitting changes its sign at a certain QW width. Our experiments show that, for most QW widths, the MPGE is mainly driven by spin-related mechanisms, which results in a photocurrent proportional to the g* factor [3]. In structures with a vanishingly small g* factor, however, the MPGE is also detected, proving the existence of orbital mechanisms.
[1] V.V. Bel’kov, S.D. Ganichev, Sem. Sci. Techn. 23, 114003 (2008),
[2] S.A. Tarasenko, arXiv cond-mat: 1009.0681v1 (2010),
[3] V. Lechner et al., arXiv cond-mat: 1011.4433v1 (2010).