Bulk Spin-Hall Effect

TL;DR

This paper demonstrates the existence of a bulk spin-Hall effect in a two-dimensional spin-orbit-coupled system with a charge/spin-density wave, revealing novel bulk charge-density wave phenomena induced by spin-gratings.

Contribution

It develops a theoretical framework for the bulk spin-Hall effect in inhomogeneous systems using spin diffusion equations, highlighting conditions for experimental observation.

Findings

Bulk charge-density waves are induced away from boundaries.

The effect exhibits a pi/2-phase shift relative to initial polarization.

The amplitude of the induced waves varies non-monotonically over time.

Abstract

We show that a two-dimensional spin-orbit-coupled system in the presence of a charge/spin-density wave with a wave-vector perpendicular to an applied electric field supports bulk manifestations of the direct/inverse spin-Hall effect. We develop a theory of this phenomenon in the framework of the spin diffusion equation formalism and show that, due to the inhomogeneity created by a spin-grating, an anomalous bulk charge-density wave is induced away from sample boundaries. The optimal conditions for the observation of the effect are determined. The main experimental manifestation of the bulk spin-Hall effect, the induced charge/spin-density-wave, is characterized by a pi/2-phase shift relative to the initial non-homogeneous spin/charge-polarization profile and has a non-monotonic time-varying amplitude.