Brownian motion of massive skyrmions forced by spin polarized currents

TL;DR

This paper investigates how thermal effects influence the Brownian motion of massive magnetic skyrmions driven by spin-polarized currents, deriving equations for their stochastic dynamics and mobility.

Contribution

It introduces a stochastic generalized Thiele's equation for massive skyrmions and relates skyrmion mass to intrinsic parameters, providing exact expressions for drift and mean-square velocities.

Findings

Derived an exact expression for skyrmion drift velocity.

Found skyrmion mass relates to damping, charge, and dissipation.

Mobility is independent of skyrmion mass at low spin velocities.

Abstract

We report on the thermal effects on the motion of current-driven massive magnetic skyrmions. The reduced equation for the motion of skyrmion has the form of a stochastic generalized Thiele's equation. We propose an ansatz for the magnetization texture of a non-rigid single skyrmion that depends linearly with the velocity. By utilizing this ansatz it is is found that the mass of skyrmion is closely related to intrinsic skyrmion parameters, such as Gilbert damping, skyrmion-charge and dissipative force. We have found an exact expression for the average drift velocity as well as the mean-square velocity of the skyrmion. The longitudinal and transverse mobility of skyrmions for small spin-velocity of electrons is also determined and found to be independent of the skyrmion mass.