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

TL;DR

This paper theoretically investigates how electrical currents induce spin polarization in a mesoscopic Rashba spin-orbit system with attached leads, revealing effects similar to the spin Hall effect and potential experimental detectability.

Contribution

It provides a detailed theoretical analysis of current-induced spin polarization in a two-terminal Rashba system, including the effects in leads and the influence of impurity scattering.

Findings

Electrical current induces spin polarization in the 2DEG and leads.

Spin polarization in leads is independent of distance from the interface, except near it.

Weak impurity scattering can enhance the lead polarization effect.

Abstract

We study theoretically the current-induced spin polarization effect in a two-terminal mesoscopic structure which is composed of a semiconductor two-dimensional electron gas (2DEG) bar with Rashba spin-orbit (SO) interaction and two attached ideal leads. The nonequilibrium spin density is calculated by solving the scattering wave functions explicitly within the ballistic transport regime. We found that for a Rashba SO system the electrical current can induce spin polarization in the SO system as well as in the ideal leads. The induced polarization in the 2DEG shows some qualitative features of the intrinsic spin Hall effect. On the other hand, the nonequilibrium spin density in the ideal leads, after being averaged in the transversal direction, is independent of the distance measured from the lead/SO system interface, except in the vicinity of the interface. Such a lead polarization effect can even be enhanced by the presence of weak impurity scattering in the SO system and may be detectable in real experiments.