Berlin 2008 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 25: Spin controlled transport I

HL 25.4: Vortrag

Dienstag, 26. Februar 2008, 15:00–15:15, EW 202

Magneto-gyrotropic photogalvanic effects due to inter-subband absorption in quantum wells — •Helgi Diehl¹, Vadim Shalygin², Sergey Danilov¹, Sergey Tarasenko³, Vasily Bel’kov³, Dieter Schuh¹, Werner Wegscheider¹, Wilhelm Prettl¹, and Sergey Ganichev¹ — ¹Terahertz Center, University of Regensburg, 93040 Regensburg, Germany — ²St. Petersburg State Polytechnical University, 195251 St. Petersburg, Russia — ³A.F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg, Russia

We report on the observation of the magneto-gyrotropic photogalvanic effect [1] due to inter-subband transitions in (001)-oriented GaAs quantum wells. This effect is related to the gyrotropic properties of the structures. It is shown that inter-subband absorption of linearly polarized radiation may lead to spin-related as well as spin-independent photocurrents if an external magnetic field is applied in the plane of the quantum well. The experimental results are analyzed in terms of the phenomenological theory and microscopic models based on either asymmetric optical excitation or asymmetric relaxation of carriers in k-space. We observed resonant photocurrents not only at oblique incidence of radiation but also at normal incidence demonstrating that conventionally applied selection rules for the inter-subband optical transitions are not rigorous.

[1] S.D. Ganichev and W. Prettl, Intense Terahertz Excitation of Semiconductors, (Oxford University Press, 2006).