Nonuniform current density and spin accumulation in a 1 {\mu}m thick n-GaAs channel

TL;DR

This study investigates spin accumulation in a 1-micrometer thick n-GaAs channel caused by spin extraction, revealing complex spatial distributions that challenge simple models and require advanced simulations for accurate understanding.

Contribution

The paper introduces a two-dimensional drift-diffusion model that accurately reproduces observed spin distributions in thick n-GaAs channels, surpassing traditional one-dimensional approaches.

Findings

Maximum spin polarization occurs near the contact edge opposite to maximum current density.

One-dimensional models fail to explain the observed spin distribution.

Numerical simulations provide realistic spin lifetime estimates.

Abstract

The spin accumulation in an n-GaAs channel produced by spin extraction into a (Ga,Mn)As contact is measured by cross-sectional imaging of the spin polarization in GaAs. The spin polarization is observed in a 1 \mum thick n-GaAs channel with the maximum polarization near the contact edge opposite to the maximum current density. The one-dimensional model of electron drift and spin diffusion frequently used cannot explain this observation. It also leads to incorrect spin lifetimes from Hanle curves with a strong bias and distance dependence. Numerical simulations based on a two-dimensional drift-diffusion model, however, reproduce the observed spin distribution quite well and lead to realistic spin lifetimes.