Tuning the Spin Hall Effect in a Two-Dimensional Electron Gas

TL;DR

This paper presents a theoretical framework for controlling the spin Hall effect in a 2D electron gas by tuning intrinsic spin-orbit coupling with a gate voltage, explaining experimental observations.

Contribution

It introduces a model that accounts for both intrinsic and extrinsic spin-orbit interactions, showing how the spin Hall conductivity can be tuned electrically.

Findings

Spin Hall conductivity can be significantly tuned by gate voltage.

Extrinsic mechanisms dominate spin Hall currents in the studied systems.

The model explains out-of-plane spin polarization observed experimentally.

Abstract

We provide a theoretical framework for the electric field control of the electron spin in systems with diffusive electron motion. The approach is valid in the experimentally important case where both intrinsic and extrinsic spin-orbit interaction in a two-dimensional electron gas are present simultaneously. Surprisingly, even when the extrinsic mechanism is the dominant driving force for spin Hall currents, the amplitude of the spin Hall conductivity may be considerably tuned by varying the intrinsic spin-orbit coupling via a gate voltage. Furthermore we provide an explanation of the experimentally observed out-of-plane spin polarization in a (110) GaAs quantum well.