Role of nonlinear anisotropic damping in the magnetization dynamics of topological solitons

TL;DR

This paper investigates how nonlinear anisotropic damping, influenced by Rashba spin-orbit coupling, impacts the dynamics of topological magnetic solitons like domain walls, vortices, and skyrmions, revealing differential effects and velocity behaviors.

Contribution

It introduces a generalized damping tensor within the Thiele formalism to analyze the effects of nonlinear anisotropic damping on various topological solitons in ferromagnetic metals.

Findings

Damping affects Bloch and Néel walls differently below Walker breakdown.

Wall velocity increases monotonically above Walker breakdown with larger Rashba coefficients.

Chiral damping components influence vortex and skyrmion dynamics distinctly.

Abstract

The consequences of nonlinear anisotropic damping, driven by the presence of Rashba spin-orbit coupling in thin ferromagnetic metals, are examined for the dynamics of topological magnetic solitons such as domain walls, vortices, and skyrmions. The damping is found to affect Bloch and N\'eel walls differently in the steady state regime below Walker breakdown and leads to a monotonic increase in the wall velocity above this transition for large values of the Rashba coefficient. For vortices and skyrmions, a generalization of the damping tensor within the Thiele formalism is presented. It is found that chiral components of the damping affect vortex- and hedgehog-like skyrmions in different ways, but the dominant effect is an overall increase in the viscous-like damping.