Abstract
We consider the possibility to extract spins that are generated by an electric current in a two-dimensional electron gas with Rashba–Dresselhaus spin–orbit interaction (R2DEG) in the Hall geometry. To this end, we discuss boundary conditions for the spin accumulations between a spin–orbit (SO) coupled region and a contact without SO coupling, i.e. a normal two-dimensional electron gas (2DEG). We demonstrate that in contrast to contacts that extend along the whole sample, a spin accumulation can diffuse into the normal region through finite contacts and be detected by e.g. ferromagnets. For an impedance-matched narrow contact the spin accumulation in the 2DEG is equal to the current induced spin accumulation in the bulk of R2DEG up to a geometry-dependent numerical factor.
Highlights
PII: S1367-2630(07)56208-7 © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft infinitely wide contact region, for which it could be shown that no spin accumulation could diffuse into the 2DEG [26]
Throughout the paper, we shall assume that all length scales of this finite region are much larger than the elastic mean free path such that spin transport is governed by diffusion equations [12, 13]
We focus on the current–voltage set-up in figure 1(b). In this case the current is perpendicular to the boundary, so the spin accumulations are continuous across an ideal R2DEG|2DEG interface
Summary
We focus on a disordered finite size 2DEG with Rashba type SO coupling, noting that the effects of a significant Dresselhaus term can be included straightforwardly. Throughout the paper, we shall assume that all length scales of this finite region are much larger than the elastic mean free path such that spin transport is governed by diffusion equations [12, 13]. We proceed to derive these spin diffusion equations for later convenience. Is the impurity potential, modeled by N impurity centers located at points {Xi }, which for the sake of simplicity we assume to be spherically symmetric, and U (x) is a smooth potential that confines the system to a finite region but allows a few openings to reservoirs
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