Collective Spin-Hall Effect for Electron-Hole Gratings

TL;DR

This paper demonstrates a collective spin Hall effect in GaAs quantum wells, where an electric field induces a significant spin grating aligned with an electron-hole density pattern, revealing complex spin-charge dynamics.

Contribution

It introduces the concept of a collective spin Hall effect in electron-hole gratings and analyzes the coupled spin-charge dynamics in quantum wells of various orientations.

Findings

Electric fields generate spin gratings exceeding 1% of initial density gratings.

Rich time evolution of spin density, including helical spin gratings.

Dependence of effects on quantum well growth directions.

Abstract

We show that an electric field parallel to the wavefronts of an electron-hole grating in a GaAs quantum well generates, via the electronic spin Hall effect, a spin grating of the same wave vector and with an amplitude that can exceed 1% of the amplitude of the initial density grating. We refer to this phenomenon as "collective spin Hall effect". A detailed study of the coupled-spin charge dynamics for quantum wells grown in different directions reveals rich features in the time evolution of the induced spin density, including the possibility of generating a helical spin grating.