# Magnetic skyrmions and skyrmion clusters in the helical phase of Cu$_2$OSeO$_3$

## TL;DR

This paper demonstrates the formation, energetics, and dynamics of skyrmions and their clusters in the helical phase of Cu$_2$OSeO$_3$, revealing their potential for spintronics applications.

## Contribution

It provides a theoretical and experimental analysis of skyrmions in the helical phase, highlighting their clustering behavior and channel confinement in Cu$_2$OSeO$_3$.

## Key findings

- Skyrmions form in the helical phase with strong attractive interactions.
- Clusters of skyrmions are observed in thin films of Cu$_2$OSeO$_3$.
- Skyrmions can move rapidly along helical channels.

## Abstract

Skyrmions are nanometric spin whirls that can be stabilized in magnets lacking inversion symmetry. The properties of isolated skyrmions embedded in a ferromagnetic background have been intensively studied. We show that single skyrmions and clusters of skyrmions can also form in the helical phase and investigate theoretically their energetics and dynamics. The helical background provides natural one-dimensional channels along which a skyrmion can move rapidly. In contrast to skyrmions in ferromagnets, the skymion-skyrmion interaction has a strong attractive component and thus skyrmions tend to form clusters with characteristic shapes. These clusters are directly observed in transmission electron microscopy measurements in thin films of Cu$_2$OSeO$_3$. Topological quantization, high mobility and the confinement of skyrmions in channels provided by the helical background may be useful for future spintronics devices.