Increased lifetime of metastable skyrmions by doping

TL;DR

Doping Cu$_2$OSeO$_3$ with 2.5% zinc significantly extends the lifetime of metastable skyrmions, enabling easier stabilization at low temperatures and advancing skyrmion-based device applications.

Contribution

This study demonstrates that minimal zinc doping dramatically increases skyrmion lifetime by reducing decay pathways, a novel approach for controlling skyrmion stability in chiral magnets.

Findings

Lifetime extended by a factor of 50 with zinc doping

Over 50% skyrmion population survives at low cooling rates

Doping removes spins, limiting decay pathways

Abstract

Previous observations of metastable magnetic skyrmions have shown that close to the equilibrium pocket the metastable state has a short lifetime, and therefore rapid cooling is required to generate a significant skyrmion population at low temperatures. Here, we report that the lifetime of metastable skyrmions in Cu$_2$OSeO$_3$ is extended by a factor of 50 with the introduction of only 2.5% zinc doping, allowing over 50% of the population to survive when field-cooling at a rate of just 1 K/min. Our systematic study suggests that the lifetime enhancement is due to the removal of spins by the non-magnetic dopant, which entropically limits the number of skyrmion decay pathways. We expect that doping can be exploited to control the lifetime of the metastable SkL state in other chiral magnets, offering a method of engineering skyrmion materials towards application in future devices.