Dresden 2009 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 34: Spin controlled transport II

HL 34.9: Vortrag

Mittwoch, 25. März 2009, 16:30–16:45, BEY 118

Spin currents in diluted magnetic semiconductors — •P. Olbrich¹, S.D. Ganichev¹, S.A. Tarasenko², V.V. Bel’kov², W. Eder¹, D.R. Yakovlev^2,3, V. Kolkovsky⁴, W. Zaleszczyk⁴, C. Karczewski⁴, T. Wojtowicz⁴, and D. Weiss¹ — ¹Terahertz Center, University of Regensburg, Regensburg, Germany — ²A.F. Ioffe Physico-Technical Institute, Russian Academy of Sciences, St. Petersburg, Russia — ³Experimental Physics 2, TU Dortmund ,Dortmund, Germany — ⁴Institute of Physics,Warsaw, Poland

We report on the observation of spin currents resulting in the zero-bias spin separation [1] in unbiased diluted magnetic semiconductor structures. We demonstrate that an absorption of THz radiation in (001)-grown (Cd,Mn)Te/(Cd,Mg)Te QWs with Mn²⁺ magnetic ions leads to a pure spin current. The effect is investigated in a magnetic field converting the spin separation into a net electric current. We demonstrate that the polarization of the magnetic ion system enhances drastically the conversion due to the spin-dependent scattering by localized Mn²⁺ ions and the giant Zeeman splitting [2]. Both effects disturb the balance of the oppositely directed spin-polarized flows yielding an electric current. In weak magnetic fields for a degenerated electron gas the scattering mechanism dominates the current conversion. We show that the spin-dependent exchange scattering of electrons by magnetic impurities plays an important role in the current generation providing a handle to manipulate the spin-polarized currents.

[1] S.D. Ganichev et al., Nature Physics (London) 2, 609 (2006)

[2] S.D. Ganichev et al., arXiv:cond-mat/0811.4327(2008)