Soliton Motion in Skyrmion Chains

TL;DR

This study models the depinning and motion of solitons in skyrmion chains, revealing their potential as low-threshold information carriers in racetrack devices with controllable skyrmion Hall angles.

Contribution

It introduces a particle-based model for soliton dynamics in skyrmion chains, highlighting their mobility at low drives and potential for information storage applications.

Findings

Solitons depin just above a critical threshold with zero skyrmion Hall angle.

At higher drives, the entire skyrmion chain depins and moves with zero skyrmion Hall angle.

In 2D systems, skyrmion Hall angles can reverse sign depending on interface orientation.

Abstract

Using a particle-based model we examine the depinning motion of solitons in skyrmion chains in quasi-one dimensional (1D) and two-dimensional (2D) systems containing embedded 1D interfaces. The solitons take the form of a particle or hole in a commensurate chain of skyrmions. Under an applied drive, just above a critical depinning threshold the soliton moves with a skyrmion Hall angle of zero. For higher drives, the entire chain depins, and in a 2D system we observe that both the solitons and chain move at zero skyrmion Hall angle and then transition to a finite skyrmion Hall angle as the drive increases. In a 2D system with a 1D interface that is at an angle to the driving direction, there can be a reversal of the sign of the skyrmion Hall angle from positive to negative. Our results suggest that solitons in skyrmion systems could be used as information carriers in racetrack geometries that would avoid the drawbacks of finite skyrmion Hall angles. The soliton states become mobile at significantly lower drives than the depinning transition of the skyrmion chains themselves.