Condensed
Matter & Surface Sciences
COLLOQUIUM
Hans-Andreas Engel
Spin
Hall Effect in GaAs
In
the spin Hall effect, an electric current in a system
with spin-orbit coupling induces a transverse spin current which leads to
non-equilibrium spin accumulation near sample boundaries. Generating and manipulating non-equilibrium
spin magnetization by electric fields is one of the most desirable goals of
semiconductor spintronics, because electric fields
have potentialities for accessing individual spins at nanometer scale. In this talk, I will review the different
spin-orbit coupling mechanisms in direct gap semiconductors and the
implications of these mechanisms for the spin Hall effect. In particular, we recently developed a theory
for spin-orbit coupling at charged scatterers. This coupling leads to extrinsic spin
currents that contain skew scattering and side jump contributions [1]. Applying our theory to bulk n-GaAs, without any free parameters, we find spin currents
that are in reasonable agreement with recent experiments by Kato et al. [2].
[1] H.-A. Engel, B.I. Halperin, and E.I. Rashba, "Theory of Spin Hall conductivity in n-doped GaAs," cond-mat/0505535.
[2]
Y.K. Kato, R.C. Myers, A.C. Gossard, and D.D. Awschalom, "Observation of the Spin Hall Effect in
Semiconductors," Science 306, 1910 (2004).