Fluctuations of current-driven domain walls in the non-adiabatic regime

TL;DR

This paper develops a framework to analyze non-equilibrium fluctuations affecting current-driven domain walls, revealing their impact on depinning times and the significance of fluctuations in narrow walls at low temperatures.

Contribution

It introduces a general method to incorporate current-induced fluctuations into the dynamics of domain walls, highlighting their effect on depinning and stability.

Findings

Current-induced fluctuations can be modeled by two effective temperatures.

Fluctuations decrease the average depinning time of domain walls.

Narrow domain walls are particularly affected by these fluctuations at low temperatures.

Abstract

We outline a general framework to determine the effect of non-equilibrium fluctuations on driven collective coordinates, and apply it to a current-driven domain wall in a nanocontact. In this case the collective coordinates are the domain-wall position and its chirality, that give rise to momentum transfer and spin transfer, respectively. We determine the current-induced fluctuations corresponding to these processes and show that at small frequencies they can be incorporated by two separate effective temperatures. As an application, the average time to depin the domain wall is calculated and found to be lowered by current-induced fluctuations. It is shown that current-induced fluctuations play an important role for narrow domain walls, especially at low temperatures.