Thermally-Assisted Current-Driven Domain Wall Motion

TL;DR

This paper develops a stochastic model for the temperature-dependent dynamics of domain walls driven by current, providing analytical expressions for velocity and aligning with experimental observations in magnetic semiconductors.

Contribution

It introduces a Langevin equation-based approach to describe thermally-assisted current-driven domain wall motion, highlighting effects at nonzero temperatures.

Findings

Average domain-wall velocity is linearly proportional to current at nonzero temperatures.

The model agrees qualitatively with recent magnetic semiconductor experiments.

Thermal effects enable domain wall motion without non-adiabatic spin torques.

Abstract

Starting from the stochastic Landau-Lifschitz-Gilbert equation, we derive Langevin equations that describe the nonzero-temperature dynamics of a rigid domain wall. We derive an expression for the average drift velocity of the domain wall as a function of the applied current, and find qualitative agreement with recent magnetic semiconductor experiments. Our model implies that at any nonzero temperature the average domain-wall velocity initially varies linearly with current, even in the absence of non-adiabatic spin torques.