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HL: Fachverband Halbleiterphysik

HL 33: Spin-dependent Transport I

HL 33.7: Vortrag

Dienstag, 15. März 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).