Magnification of spin Hall effect in bilayer electron gas

TL;DR

This paper investigates the spin Hall effect in a bilayer electron gas with Rashba spin-orbit coupling, revealing sharp features in conductivity and proposing an experimental detection method.

Contribution

It introduces a detailed analysis of spin transport in bilayer systems, highlighting the magnification of the spin Hall effect and the robustness against impurities.

Findings

Sharp cusps in spin Hall conductivity at specific tunneling strengths

Sign changes in conductivity across the cusp points

Impurity effects do not suppress the spin Hall effect in bilayer systems

Abstract

Spin transport properties of a coupled bilayer electron gas with Rashba spin-orbit coupling are studied. The definition of the spin currents in each layer as well as the corresponding continuity-like equations in the bilayer system are given. The curves of the spin Hall conductivities obtained in each layer exhibit sharp cusps around a particular value of the tunnelling strength and the conductivities undergo sign changes across this point. Our investigation on the impurity effect manifests that an arbitrarily small concentration of nonmagnetic impurities does not suppress the spin Hall conductivity to zero in the bilayer system. Based on these features, an experimental scheme is suggested to detect a magnification of the spin Hall effect.