Reversal of the skyrmion topological deflection across ferrimagnetic angular momentum compensation

TL;DR

This study demonstrates that the topological deflection of skyrmions in ferrimagnetic GdCo films reverses across the angular momentum compensation temperature, enabling potential deflection-free skyrmion device applications.

Contribution

The paper provides experimental evidence of skyrmion deflection reversal across the angular momentum compensation point in ferrimagnetic materials, showing how to tune skyrmion trajectories.

Findings

Skyrmion deflection angle reverses at the TAC in GdCo films.

Angular momentum density controls skyrmion trajectory direction.

Tuning composition affects skyrmion stability and dynamics.

Abstract

Due to their non-trivial topology, skyrmions describe deflected trajectories, which hinders their straight propagation in nanotracks and can lead to their annihilation at the track edges. This deflection is caused by a gyrotropic force proportional to the topological charge and the angular momentum density of the host film. In this article we present clear evidence of the reversal of the topological deflection angle of skyrmions with the sign of angular momentum density. We measured the skyrmion trajectories across the angular momentum compensation temperature (TAC) in GdCo thin films, a rare earth/transition metal ferrimagnetic alloy. The sample composition was used to engineer the skyrmion stability below and above the TAC. A refined comparison of their dynamical properties evidenced a reversal of the skyrmions deflection angle with the total angular momentum density. This reversal is a clear demonstration of the possibility of tuning the skyrmion deflection angle in ferrimagnetic materials and paves the way for deflection-free skyrmion devices.