Ultrafast generation and dynamics of isolated skyrmions in antiferromagnetic insulators

TL;DR

This paper demonstrates the ultrafast creation of isolated antiferromagnetic skyrmions using laser pulses, explores their size modulation with magnetic fields and temperature, and analyzes their rapid thermally driven motion.

Contribution

It introduces a method for ultrafast skyrmion generation in antiferromagnets via the inverse Faraday effect and studies their dynamics under thermal gradients.

Findings

Skyrmions can be nucleated ultrafast using laser-induced magnetic fields.

Skyrmion size increases with applied magnetic field and temperature.

Antiferromagnetic skyrmions exhibit fast thermally driven motion toward hotter regions.

Abstract

Based on atomistic spin dynamics simulations, we report the ultrafast generation of single antiferromagnetic (AFM) skyrmions in a confined geometry. This process is achieved through an effective magnetic field induced by the athermal inverse Faraday effect from a short laser pulse. The resulting field can nucleate an isolated skyrmion as a topologically protected metastable state in a collinear antiferromagnet with small Dzyaloshinskii-Moriya interaction. The radius of a single skyrmion is shown to increase by applying a uniform dc magnetic field and at increasing temperature. To investigate possible AFM spin-caloritronics phenomena, we investigate the skyrmion dynamics under an applied temperature gradient both analytically and numerically. The antiferromagnetic skyrmions move longitudinally toward the hotter region, but in contrast, small skyrmions in the very low damping regime move toward the colder side, irrespective of the staggered topological charge number, with a speed that is much faster than that of their ferromagnetic counterparts.