Spin currents in a normal two-dimensional electron gas in contact with a spin-orbit interaction region

TL;DR

This paper investigates spin currents and spin responses in a 2D electron gas with spin-orbit interaction, revealing how electron currents influence spin distributions and generate polarized spin currents near interfaces.

Contribution

It introduces a detailed analysis of spin-dependent scattering effects and the resulting spin currents in a 2D electron gas with spin-orbit coupling, highlighting new mechanisms of spin polarization.

Findings

Equilibrium edge spin current exists due to spin-dependent scattering.

Parallel electron current induces spin density and modifies edge spin current.

Perpendicular electron current generates a bulk spin current with high polarization.

Abstract

Spin effects in a normal two-dimensional (2D) electron gas in lateral contact with a 2D region with spin-orbit interaction are studied. The peculiarity of this system is the presence of spin-dependent scattering of electrons from the interface. This results in an equilibrium edge spin current and nontrivial spin responses to a particle current. We investigate the spatial distribution of the spin currents and spin density under non-equilibrium conditions caused by a ballistic electron current flowing normal or parallel to the interface. The parallel electron current is found to generate the spin density near the interface and to change the edge spin current. The perpendicular electron current changes the edge spin current proportionally to the electron current and produces a bulk spin current penetrating deep into the normal region. This spin current has two components, one of which is directed normal to the interface and polarized parallel to it, and the second is parallel to the interface and is polarized in the plane perpendicular to the contact line. Both spin currents have a high degree of polarization ($\sim 40-60%$).