Thermal motion of skyrmion arrays in granular films

Abstract

Magnetic skyrmions are topologically-distinct swirls of magnetic moments which display particle-like behaviour, including the ability to undergo thermally-driven diffusion. In this paper we study the thermally activated motion of arrays of skyrmions using temperature dependent micromagnetic simulations where the skyrmions form spontaneously. In particular, we study the interaction of skyrmions with grain boundaries, which are a typical feature of sputtered ultrathin films used in experimental devices. We find the interactions lead to two distinct regimes. For longer lag times the grains lead to a reduction in the diffusion coefficient, which is strongest for grain sizes similar to the skyrmion diameter. At shorter lag times the presence of grains enhances the effective diffusion coefficient due to the gyrotropic motion of the skyrmions induced by their interactions with grain boundaries. For grain sizes significantly larger than the skyrmion diameter clustering of the skyrmions occurs in grains with lower magnetic anisotropy.

7 pages, 5 figures

References in corpus (9)

• Magnetic skyrmion logic gates: conversion, duplication and merging of skyrmions
• Theory of current-driven motion of Skyrmions and spirals in helical magnets
• Skyrmion-skyrmion and skyrmion-edge repulsions in skyrmion-based racetrack memory
• Inertia, diffusion and dynamics of a driven skyrmion
• Magnetic skyrmions in confined geometries : effect of the magnetic field and the disorder
• Brownian motion of massive skyrmions forced by spin polarized currents
• Temperature scaling of the Dzyaloshinsky-Moriya interaction in the spin wave spectrum
• Skyrmion relaxation dynamics in the presence of quenched disorder
• Configurational entropy of magnetic skyrmions as an ideal gas