Thermal Creep and the Skyrmion Hall Angle in Driven Skyrmion Crystals

TL;DR

This study uses numerical simulations to explore how thermal effects influence the skyrmion Hall angle in driven skyrmion systems with disorder, revealing a creep regime with zero Hall angle and a viscous flow regime with a finite Hall angle.

Contribution

It identifies the thermal-dependent crossover between creep and viscous flow regimes in skyrmion dynamics, aligning with recent experimental observations.

Findings

Creep regime exhibits zero skyrmion Hall angle due to pinning.

Higher drives lead to a finite skyrmion Hall angle increasing with drive and temperature.

Results agree with recent experimental data on skyrmion motion.

Abstract

We numerically examine thermal effects on the skyrmion Hall angle for driven skyrmions interacting with quenched disorder. We identify a creep regime in which motion occurs via intermittent jumps between pinned and flowing states. Here the skyrmion Hall angle is zero since the skyrmions have time to relax into equilibrium positions in the pinning sites, eliminating the side-jump motion induced by the Magnus force. At higher drives we find a crossover to a viscous flow regime where the skyrmion Hall angle is finite and increases with increasing drive or temperature. Our results are in agreement with recent experiments which also show a regime of finite skyrmion velocity with zero skyrmion Hall angle crossing over to a viscous flow regime with a skyrmion Hall angle that increases with drive.