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Influences of spin accumulation on the intrinsic spin Hall effect in two dimensional electron gases with Rashba spin-orbit coupling
In a two dimensional electron gas with Rashba spin-orbit coupling, the
external electric field may cause a spin Hall current in the direction
perpendicular to the electric field. This effect was called the intrinsic spin
Hall effect. In this paper, we investigate the influences of spin accumulation
on this intrinsic spin Hall effect. We show that due to the existence of
boundaries in a real sample, the spin Hall current generated by the intrinsic
spin Hall effect will cause spin accumulation near the edges of the sample, and
in the presence of spin accumulation, the spin Hall conductivity will not have
a universal value. The influences of spin accumulation on the intrinsic spin
Hall effect in narrow strips of two dimensional electron gases with Rashba
spin-orbit coupling are investigated in detail.Comment: 7 pages, 2 figure
Intrinsic Spin and Orbital-Angular-Momentum Hall Effect
A generalized definition of intrinsic and extrinsic transport coefficients is
introduced. We show that transport coefficients from the intrinsic origin are
solely determined by local electronic structure, and thus the intrinsic spin
Hall effect is not a transport phenomenon. The intrinsic spin Hall current is
always accompanied by an equal but opposite intrinsic orbital-angular-momentum
Hall current. We prove that the intrinsic spin Hall effect does not induce a
spin accumulation at the edge of the sample or near the interface.Comment: References update
Anomalous spin Hall effects in Dresselhaus (110) quantum wells
Anomalous spin Hall effects that belong to the intrinsic type in Dresselhaus
(110) quantum wells are discussed. For the out-of-plane spin component,
antisymmetric current-induced spin polarization induces opposite spin Hall
accumulation, even though there is no spin-orbit force due to Dresselhaus (110)
coupling. A surprising feature of this spin Hall induction is that the spin
accumulation sign does not change upon bias reversal. Contribution to the spin
Hall accumulation from the spin Hall induction and the spin deviation due to
intrinsic spin-orbit force as well as extrinsic spin scattering, can be
straightforwardly distinguished simply by reversing the bias. For the inplane
component, inclusion of a weak Rashba coupling leads to a new type of
intrinsic spin Hall effect solely due to spin-orbit-force-driven spin
separation.Comment: 6 pages, 5 figure
Intrinsic Spin Hall Effect
A brief review is given on the spin Hall effect, where an external electric
field induces a transverse spin current. It has been recognized over 30 years
that such effect occurs due to impurities in the presence of spin-orbit
coupling. Meanwhile, it was proposed recently that there is also an intrinsic
contribution for this effect. We explain the mechanism for this intrinsic spin
Hall effect. We also discuss recent experimental observations of the spin Hall
effect.Comment: 13 pages, 3 figures, to appear in Advances in Solid State Physics,
Vol 45(2005), edited by B. Kramer, changes in Sections 3 and 4.
Intrinsic Spin Hall Effect in the Two Dimensional Hole Gas
We show that two types of spin-orbit coupling in the 2 dimensional hole gas
(2DHG), with and without inversion symmetry breaking, contribute to the
intrinsic spin Hall effect\cite{murakami2003,sinova2003}. Furthermore, the
vertex correction due to impurity scattering vanishes in both cases, in sharp
contrast to the case of usual Rashba coupling in the electron band. Recently,
the spin Hall effect in a hole doped semiconductor has been observed
experimentally by Wunderlich \emph{et al}\cite{wunderlich2004}. From the fact
that the life time broadening is smaller than the spin splitting, and the fact
impurity vertex corrections vanish in this system, we argue that the observed
spin Hall effect should be in the intrinsic regime.Comment: Minor typos fixed, one reference adde
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