Micromagnetic study of skyrmion stability in confined magnetic structures with perpendicular anisotropy

TL;DR

This study uses micromagnetic simulations to explore the stability of skyrmions in confined magnetic structures with perpendicular anisotropy, providing insights for their potential use in spintronic devices.

Contribution

It offers a comprehensive micromagnetic analysis of skyrmion stability in cobalt disks considering various anisotropy, DMI, and geometric parameters, extending understanding of their robustness.

Findings

Stable skyrmions occur for specific DMI and anisotropy values.

Skyrmions remain stable under magnetic field and current in certain conditions.

Temperature affects skyrmion stability limits.

Abstract

Skyrmions are emerging topological spin structures that are potentially revolutionary for future data storage and spintronics applications. The existence and stability of skyrmions in magnetic materials is usually associated to the presence of the Dzyaloshinskii-Moriya interaction (DMI) in bulk magnets or in magnetic thin films lacking inversion symmetry. While some methods have already been proposed to generate isolated skyrmions in thin films with DMI, a thorough study of the conditions under which the skyrmions will remain stable in order to be manipulated in an integrated spintronic device are still an open problem. The stability of such structures is believed to be a result of ideal combinations of perpendicular magnetic anisotropy (PMA), DMI and the interplay between geometry and magnetostatics. In the present work we show some micromagnetic results supporting previous experimental observations of magnetic skyrmions in spin-valve stacks with a wide range of DMI values. Using micromagnetic simulations of cobalt-based disks, we obtain the magnetic ground state configuration for several values of PMA, DMI and geometric parameters. Skyrmion numbers, corresponding to the topological charge, are calculated in all cases and confirm the occurrence of isolated, stable, axially symmetric skyrmions for several combinations of DMI and anisotropy constant. The stability of the skyrmions in disks is then investigated under magnetic field and spin-polarized current, in finite temperature, highlighting the limits of applicability of these spin textures in spintronic devices.