Topologically stable magnetization states on a spherical shell: curvature stabilized skyrmions

TL;DR

This paper investigates the stability and topology of magnetization states, especially skyrmions, on spherical shells, revealing curvature effects can stabilize skyrmions without Dzyaloshinskii-Moriya interactions.

Contribution

It demonstrates that curvature stabilizes skyrmions on spherical shells, which are topologically trivial and can be induced by uniform magnetic fields, expanding understanding of magnetic textures on curved surfaces.

Findings

Skyrmions on spherical shells are topologically trivial.

Curvature effects can stabilize skyrmions without Dzyaloshinskii-Moriya interactions.

A uniform magnetic field can induce skyrmions on spherical shells.

Abstract

Topologically stable structures include vortices in a wide variety of matter, such as skyrmions in ferro- and antiferromagnets, and hedgehog point defects in liquid crystals and ferromagnets. These are characterized by integer-valued topological quantum numbers. In this context, closed surfaces are a prominent subject of study as they form a link between fundamental mathematical theorems and real physical systems. Here we perform an analysis on the topology and stability of equilibrium magnetization states for a thin spherical shell with easy-axis anisotropy in normal directions. Skyrmion solutions are found for a range of parameters. These magnetic skyrmions on a spherical shell have two distinct differences compared to their planar counterpart: (i) they are topologically trivial, and (ii) can be stabilized by curvature effects, even when Dzyaloshinskii-Moriya interactions are absent. Due to its specific topological nature a skyrmion on a spherical shell can be simply induced by a uniform external magnetic field.