# Solitary wave excitations of skyrmion strings in chiral magnets

## TL;DR

This paper investigates the existence and properties of solitary wave excitations along skyrmion strings in chiral magnets, combining analytical models with micromagnetic simulations to reveal their non-reciprocal behavior and existence conditions.

## Contribution

It provides a new analytical and numerical study of solitary waves on skyrmion strings, including an effective field theory and confirmation through simulations, highlighting their non-reciprocal nature.

## Key findings

- Solitary waves exist on skyrmion strings in chiral magnets.
- These waves are generally non-reciprocal, depending on their velocity sign.
- Analytical results match micromagnetic simulations for FeGe parameters.

## Abstract

Chiral magnets possess topological line excitations where the magnetization within each cross section forms a skyrmion texture. We study analytically and numerically the low-energy, non-linear dynamics of such a skyrmion string in a field-polarized cubic chiral magnet, and we demonstrate that it supports solitary waves. Theses waves are in general non-reciprocal, i.e., their properties depend on the sign of their velocity $v$, but this non-reciprocity diminishes with decreasing $|v|$. An effective field-theoretical description of the solitary waves is derived that is valid in the limit $v \to 0$ and gives access to their profiles and their existence regime. Our analytical results are quantitatively confirmed with micromagnetic simulations for parameters appropriate for the chiral magnet FeGe. Similarities with solitary waves found in vortex filaments of fluids are pointed out.