Direct demonstration of topological stability of magnetic skyrmions via topology manipulation

TL;DR

This study provides direct experimental evidence that magnetic skyrmions exhibit topological stability in real materials, showing longer lifetimes than trivial bubbles, which supports their potential use as stable nanometer-scale information carriers.

Contribution

The paper demonstrates a method to selectively create skyrmion and bubble states in a single sample, directly comparing their stability and confirming the topological protection of skyrmions in discrete atomic systems.

Findings

Skyrmions have longer lifetimes than bubbles, indicating topological stability.

The method allows direct comparison of topologically distinct states in one sample.

Results support the physical relevance of topology in magnetic materials.

Abstract

Topological protection precludes a continuous deformation between topologically inequivalent configurations in a continuum. Motivated by this concept, magnetic skyrmions, topologically nontrivial spin textures, are expected to exhibit the topological stability, thereby offering a prospect as a nanometer-scale non-volatile information carrier. In real materials, however, atomic spins are configured as not continuous but discrete distribution, which raises a fundamental question if the topological stability is indeed preserved for real magnetic skyrmions. Answering this question necessitates a direct comparison between topologically nontrivial and trivial spin textures, but the direct comparison in one sample under the same magnetic fields has been challenging. Here we report how to selectively achieve either a skyrmion state or a topologically trivial bubble state in a single specimen and thereby show how robust the skyrmion structure is in comparison with the bubbles for the first time. We demonstrate that topologically nontrivial magnetic skyrmions show longer lifetimes than trivial bubble structures, evidencing the topological stability in a real discrete system. Our work corroborates the physical importance of the topology in the magnetic materials, which has hitherto been suggested by mathematical arguments, providing an important step towards ever-dense and more-stable magnetic devices.