Skyrmionium Dynamics and Stability on One Dimensional Anisotropy Patterns

TL;DR

This paper investigates the behavior, stability, and transformations of skyrmionium structures on one-dimensional anisotropy patterns, revealing how disorder and external drives influence their dynamics and stability.

Contribution

It provides new insights into skyrmionium stability and transformation mechanisms under disorder and external drives, including the effects of transverse shaking.

Findings

Skyrmionium flows over a range of currents in low disorder conditions.

Higher disorder densities decrease the current needed for skyrmionium to transform into a skyrmion.

Adding transverse shaking drives increases skyrmionium lifetime by reducing pinning effects.

Abstract

We examine a skyrmionium driven over a periodic anisotropy pattern, which consists of disorder free regions and disordered regions. For small defect densities, the skyrmionium flows for an extended range of currents, and there is a critical current above which it transforms into a skyrmion. For increased amounts of quenched disorder, the current needed for the skyrmionium to transform into a skyrmion decreases, and there is a critical disorder density above which a moving skyrmionium is not stable. In the moving state, the skyrmionium to skyrmion transformation leads to a drop in the velocity and the onset of a finite skyrmion Hall angle. We also find a reentrance effect in which the pinned skyrmionium transforms into a skyrmion just above depinning, restabilizes into skyrmionium at larger drives, and becomes unstable again at large currents. We also show that adding a transverse shaking drive can increase the lifetime of a moving skyrmionium by reducing the effect of the pinning in the direction of the drive.