Regensburg 2007 – wissenschaftliches Programm

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SYSS: Symposium Spins in Semiconductors

SYSS 1: Spins in Semiconductors

SYSS 1.10: Hauptvortrag

Montag, 26. März 2007, 12:40–13:00, H1

Zero-bias spin separation in semiconductor heterostructures — •Sergey Ganichev — Faculty of Physics, University of Regensburg, 93040, Regensburg, Germany

We observed that spin-dependent scattering of electrons in media with suitable symmetry results in in equal and oppositely directed electron flows in the spin-up and spin-down subbands yielding a pure spin current [1]. The pure spin current does not require an electric current to flow, as in the case of the spin-Hall effect, and causes a ”zero-bias” spin separation. It is show that by free carrier (Drude) absorption of terahertz radiation [2] spin separation can be achieved in a wide range of temperatures from liquid helium temperature up to room temperature. Moreover the experimental results demonstrate that simple electron gas heating by any means is already sufficient to yield spin separation due to spin-dependent energy relaxation processes of non-equilibrium carriers. In our experiments on low dimensional structures based on GaAs, InAs, SiGe and GaN 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 is developed being in a good agreement with the experimental data.

[1] S.D. Ganichev, V.V. Bel’kov, S.A. Tarasenko, S.N. Danilov, S. Giglberger, Ch. Hoffmann, E.L. Ivchenko, D. Weiss, W. Wegscheider, Ch. Gerl, D. Schuh, J. Stahl, J. De Boeck, G. Borghs, and W. Prettl, Nature Physics (London) 2, 609 (2006).

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