# Dynamical defects in rotating magnetic skyrmion lattices

## TL;DR

This study investigates the dynamic behavior of skyrmion lattices in Cu₂OSeO₃ under thermal gradients, revealing defect-driven boundary rearrangements that support the particle-like nature of skyrmions.

## Contribution

It demonstrates how inhomogeneous temperature gradients induce rotating skyrmion domains and elucidates defect dynamics governing boundary fluctuations, supported by experiments and simulations.

## Key findings

- Domain walls are constantly rearranged by dynamic 5-7 defects.
- Defect density analysis aligns with Frank's equation and Monte Carlo simulations.
- Boundary fluctuations involve surge-like skyrmion cluster rearrangements.

## Abstract

The chiral magnet Cu$_{2}$OSeO$_{3}$ hosts a skyrmion lattice, that may be equivalently described as a superposition of plane waves or lattice of particle-like topological objects. A thermal gradient may break up the skyrmion lattice and induce rotating domains raising the question which of these scenarios better describes the violent dynamics at the domain boundaries. Here we show that in an inhomogeneous temperature gradient caused by illumination in a Lorentz Transmission Electron Microscope different parts of the skyrmion lattice can be set into motion with different angular velocities. Tracking the time dependence we show that the constant rearrangement of domain walls is governed by dynamic 5-7 defects arranging into lines. An analysis of the associated defect density is described by Frank's equation and agrees well with classical 2D-Monte Carlo simulations. Fluctuations of boundaries show surge-like rearrangement of skyrmion clusters driven by defect rearrangement consistent with simulations treating skyrmions as point particles. Our findings underline the particle character of the skyrmion.