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HL: Halbleiterphysik

HL 13: Spin controlled transport I

HL 13.8: Vortrag

Dienstag, 28. März 2006, 12:45–13:00, BEY 118

Pure Spin Currents by Spin Dependent Electron Phonon Interaction — •Stephan Giglberger¹, S.D. Ganichev¹, S.N. Danilov¹, V.V. Belkov², E.L. Ivchenko², S.A. Tarasenko², D. Weiss¹, W. Prettl¹, W. Janzsch³, F. Schaffler³, and D. Gruber³ — ¹Institut für Experimentelle und Angewandte Physik, Universität Regensburg, 93040 Regensburg — ²A.F. Ioffe Physico-Technical Institute, 194021 St. Petersburg, Russland — ³Institut für Halbleiter- und Festkörperphysik, Johannes-Kepler-Universität, Linz, Österreich

It is shown that in gyrotropic quantum wells Drude absorption of terahertz radiation leads to a pure spin current. This current is caused by spin dependent electron phonon interaction wich can be described by k-linear terms in their matrix element. Due to these k-linear terms Drude absorption leads to an asymmetric allocation of charge carriers within each subband and hence to a spinpolarised electric current. Due to the fact that direction of this current is antipodal for both spin subbbands the resulting electric net current will be zero, but there will be two spin currents. Here both the theory and the experimental verification of such spin currents will be presented. In experiment the pure spin current was converted to an electric current by applying a small magnetic field parallel to the plane which leads to Zeeman spin splitting and destroys the equilibrium of the opposing spin currents. Experiments were carried out on (001)-oriented asymmetric SiGe quantum wells under excitation with linearly polarised radiation of 140 µm wavelength.