Spontaneous creation and annihilation dynamics and strain-limited stability of magnetic skyrmions

TL;DR

This paper investigates the dynamic behavior of magnetic skyrmions, revealing spontaneous creation and annihilation processes driven by local energy conditions, and explores their stability limits and potential control mechanisms.

Contribution

It provides direct experimental evidence of spontaneous skyrmion creation and annihilation, highlighting the influence of local energy environments on their stability and dynamics.

Findings

Skyrmions can spontaneously merge or spawn in high exchange energy regions.

Transitions involve distinct configurational states with creation or annihilation events.

Results challenge the understanding of topological charge conservation in skyrmion dynamics.

Abstract

Magnetic skyrmions are topological magnetic spin structures exhibiting particle-like behaviour. They are of strong interest from a fundamental viewpoint and for application, where they have potential to act as information carriers in future low-power computing technologies. Importantly, skyrmions have high physical stability because of topological protection. However, they have potential to deform according to their local energy environment. Here we demonstrate that, in regions of high exchange energy density, skyrmions may exhibit such extreme deformation that spontaneous merging with nearest neighbours or spawning new skyrmions is favoured to attain a lower energy state. Using transmission electron microscopy and a high-speed imaging detector, we observe dynamics involving distinct configurational states, in which transitions are accompanied by spontaneous creation or annihilation of skyrmions. These observations raise important questions regarding the limits of skyrmion stability and topological charge conservation, while also suggesting a means of control of skyrmion creation and annihilation.