Breathing skyrmions in chiral antiferromagnets

TL;DR

This paper investigates the dynamics of breathing skyrmions in chiral antiferromagnets, deriving a potential formula, analyzing nonlinear oscillations, and predicting skyrmion annihilation due to large amplitude breathing modes.

Contribution

It introduces a theoretical framework for understanding breathing oscillations in antiferromagnetic skyrmions and predicts annihilation events driven by large amplitude oscillations.

Findings

Derived a potential formula for breathing skyrmions.

Identified a maximum amplitude for oscillations leading to annihilation.

Observed nonzero kinetic energy at skyrmion annihilation.

Abstract

Breathing oscillations of skyrmions in chiral antiferromagnets can be excited by a temporal modification of the Dzyaloshinskii-Moriya interaction or magnetocrystalline anisotropy strength. We employ an adiabatic approximation and derive a formula for the potential that directly implies breathing oscillations. We study the nonlinear regime and the features of larger amplitude oscillations. We show that there is a maximum amplitude supported by the potential. As a consequence, we predict theoretically and observe numerically skyrmion annihilation events due to excitation of large amplitude breathing oscillations. The process is efficient when the skyrmion is mildly excited so that its radius initially grows, while the annihilation event is eventually induced by the internal breathing dynamics. We reveal the counter-intuitive property that the skyrmion possesses a nonzero kinetic energy at the moment of its annihilation. Finally, the frequency of small amplitude breathing oscillations is determined.