Spatial imaging of the spin Hall effect and current-induced polarization in two-dimensional electron gases

TL;DR

This study uses Kerr rotation microscopy to explore the spin Hall effect and current-induced spin polarization in a 2D electron gas within AlGaAs quantum wells, revealing complex spin profiles and anisotropic effects.

Contribution

It demonstrates how quantum confinement and device engineering can tune spin phenomena in non-magnetic semiconductor heterostructures.

Findings

Complex spin Hall profiles observed

Out-of-plane current-induced spin polarization detected

Strong dependence on electric field direction and crystal axis

Abstract

Spin-orbit coupling in semiconductors relates the spin of an electron to its momentum and provides a pathway for electrically initializing and manipulating electron spins for applications in spintronics and spin-based quantum information processing. This coupling can be regulated with quantum confinement in semiconductor heterostructures through band structure engineering. Here we investigate the spin Hall effect and current-induced spin polarization in a two-dimensional electron gas confined in (110) AlGaAs quantum wells using Kerr rotation microscopy. In contrast to previous measurements, the spin Hall profile exhibits complex structure, and the current-induced spin polarization is out-of-plane. The experiments map the strong dependence of the current-induced spin polarization to the crystal axis along which the electric field is applied, reflecting the anisotropy of the spin-orbit interaction. These results reveal opportunities for tuning a spin source using quantum confinement and device engineering in non-magnetic materials.