Skyrmion-antiskyrmion droplets in a chiral ferromagnet

TL;DR

This paper numerically discovers stable skyrmion-antiskyrmion pair textures, called chiral droplets, in chiral ferromagnets with Dzyaloshinskii-Moriya interaction, revealing their unique dynamics under spin-transfer torque.

Contribution

It introduces the concept of chiral droplets as stable Q=0 skyrmion-antiskyrmion pairs in ferromagnets, expanding understanding of topological textures.

Findings

Chiral droplets are stable in infinite films and discs.

They move with the spin flow, unlike standard skyrmions.

Stability occurs near the ferromagnetic to spiral phase transition.

Abstract

We find numerically skyrmionic textures with skyrmion number Q=0 in ferromagnets with the Dzyaloshinskii-Moriya interaction and perpendicular anisotropy. These have the form of a skyrmion-antiskyrmion pair and may be called chiral droplets. They are stable in an infinite film as well as in disc-shaped magnetic elements. Droplets are found for values of the parameters close to the transition from the ferromagnetic to the spiral phase. We study their motion under spin-transfer torque. They move in the direction of the spin flow and, thus, their dynamics are drastically different than the Hall dynamics of the standard Q=0 skyrmion.