Pure spin currents induced by spin-dependent scattering processes in SiGe quantum well structures

S. D. Ganichev, S. N. Danilov, V. V. Bel'kov, S. Giglberger, S. A. Tarasenko, E. L. Ivchenko, D. Weiss, W. Jantsch, F. Schaeffler, D. Gruber, W. Prettl

Published 2006-10-26Version 1

We show that spin-dependent electron-phonon interaction in the energy relaxation of a two-dimensional electron gas results in equal and oppositely directed currents in the spin-up and spin-down subbands yielding a pure spin current. In our experiments on SiGe heterostructures the pure spin current is converted into an electric current applying a magnetic field that lifts the cancellation of the two partial charge flows. A microscopic theory of this effect, taking account of the asymmetry of the relaxation process, is developed being in a good agreement with the experimental data.