Non-equilibrium spin polarization effects in spin-orbit coupling system and contacting metallic leads

摘要

We study theoretically the current-induced spin polarization effect in atwo-terminal mesoscopic structure which is composed of a semiconductortwo-dimensional electron gas (2DEG) bar with Rashba spin-orbit (SO) interactionand two attached ideal leads. The nonequilibrium spin density is calculated bysolving the scattering wave functions explicitly within the ballistic transportregime. We found that for a Rashba SO system the electrical current can inducespin polarization in the SO system as well as in the ideal leads. The inducedpolarization in the 2DEG shows some qualitative features of the intrinsic spinHall effect. On the other hand, the nonequilibrium spin density in the idealleads, after being averaged in the transversal direction, is independent of thedistance measured from the lead/SO system interface, except in the vicinity ofthe interface. Such a lead polarization effect can even be enhanced by thepresence of weak impurity scattering in the SO system and may be detectable inreal experiments.