# Current-driven skyrmion dynamics in disordered films

## TL;DR

This paper presents a theoretical analysis of how magnetic skyrmions move in disordered ultrathin films under current, revealing pinning effects, Hall effect variations, and core radius fluctuations due to disorder.

## Contribution

It introduces a model simulating disorder as grain-to-grain anisotropy variations and analyzes skyrmion dynamics and Hall effect behavior under different current regimes.

## Key findings

- Skyrmion velocity exhibits pinning at low currents and transitions to disorder-free behavior at higher currents.
- Current-dependent skyrmion Hall effect and core radius fluctuations are observed due to pinning interactions.
- Disorder influences skyrmion motion similarly to domain wall dynamics in disordered films.

## Abstract

A theoretical study of the current-driven dynamics of magnetic skyrmions in disordered perpendicularly-magnetized ultrathin films is presented. The disorder is simulated as a granular structure in which the local anisotropy varies randomly from grain to grain. The skyrmion velocity is computed for different disorder parameters and ensembles. Similar behavior is seen for spin-torques due to in-plane currents and the spin Hall effect, where a pinning regime can be identified at low currents with a transition towards the disorder-free case at higher currents, similar to domain wall motion in disordered films. Moreover, a current-dependent skyrmion Hall effect and fluctuations in the core radius are found, which result from the interaction with the pinning potential.