Theory of Topological Spin Hall Effect in Antiferromagnetic Skyrmion: Impact on Current-induced Motion

TL;DR

This paper develops a theoretical framework showing that antiferromagnetic skyrmions induce a topological spin Hall effect, which enhances current-driven motion and can be optimized through size, defects, and disorder.

Contribution

It introduces a novel theory of the topological spin Hall effect in antiferromagnetic skyrmions and explores how it can be manipulated for improved skyrmion mobility.

Findings

TSHE is non-zero in AFM-Sks due to magnetic texture.

Reducing skyrmion size increases non-adiabatic torque.

Disorder enhances TSHE in AFM-Sks.

Abstract

We demonstrate that the nontrivial magnetic texture of antiferromagnetic skyrmions (AFM-Sks) promotes a non-vanishing topological spin Hall effect (TSHE) on the flowing electrons. This results in a substantial enhancement of the non-adiabatic torque and hence improves the skyrmion mobility. This non-adiabatic torque increases when decreasing the skyrmion size, and therefore scaling down results in a much higher torque efficiency. In clean AFM-Sks, we find a significant boost of the TSHE close to van Hove singularity. Interestingly, this effect is enhanced away from the band gap in the presence of non-magnetic interstitial defects. Furthermore, unlike their ferromagnetic counterpart, TSHE in AFM-Sks increases with increase in disorder strength thus opening promising avenues for materials engineering of this effect.