Nonlinear dynamics of topological helicity wave in a frustrated skyrmion string

TL;DR

This paper investigates the nonlinear dynamics of helicity waves in a frustrated skyrmion string modeled by a dimerized XY system, revealing topological properties through quench dynamics.

Contribution

It introduces a nonlinear topological model of skyrmion helicity dynamics using a dimerized XY framework related to the Su-Schrieffer-Heeger model.

Findings

Helicity wave dynamics distinguish topological from trivial phases.

Rich nonlinear physics observed in modulated exchange-coupled skyrmion strings.

Quench dynamics serve as a signal for topological characterization.

Abstract

A skyrmion in frustrated magnetic system has the helicity degree of freedom. A skyrmion string is formed in a frustrated layered system, which is well described by the $XY$ model owing to the exchange coupling between adjacent layers. We consider a system where the interlayer exchange couplings are alternating, where the dimerized $XY$ model is materialized, whose linear limit is the Su-Schrieffer-Heeger model. We argue that it is a nonlinear topological system. We study the quench dynamics of the helicity wave under the initial condition that the helicity of the skyrmion in the bottommost layer is rotated. It yields a good signal to detect whether the system is topological or trivial. Our results show that the helicity dynamics of the skyrmion string have a rich physics in the modulated exchange-coupled system.