Strongly enhanced lifetime of higher-order bimerons and antibimerons

TL;DR

This study demonstrates that high-$Q$ bimerons are significantly more stable than high-$Q$ skyrmions across various temperatures, with potential implications for magnetic storage technologies.

Contribution

First calculations of lifetimes for high-$Q$ bimerons showing enhanced stability over skyrmions, emphasizing entropy's role in their longevity.

Findings

High-$Q$ bimerons' lifetimes exceed those of $|Q|=1$ by 3 orders of magnitude.

Lifetimes of high-$Q$ bimerons remain stable even at room temperature.

Distinct magnetic symmetries cause different entropy effects in skyrmions and bimerons.

Abstract

Magnetic bimerons, similar to skyrmions, are topologically nontrivial spin textures characterized by topological charge $Q$. Most studies so far have focused on low-$Q$ solitons ($|Q| \leq 1$), such as skyrmions, bimerons, and vortices. Here, we present the first calculations of the lifetimes of {ring-like} high-$Q$ bimerons and demonstrate that they are fundamentally more stable than high-$Q$ skyrmions over a wide range of temperature. To obtain realistic results, our chosen system is an experimentally feasible van der Waals interface, Fe$_3$GeTe$_2$/Cr$_2$Ge$_2$Te$_6$. We show that the lifetimes of high-$Q$ (anti)bimerons can exceed the lifetime of those with $|Q|=1$ by 3 orders of magnitude. Remarkably, this trend remains valid even when extrapolated to room temperature (RT), as the lifetimes are dominated by entropy rather than energy barriers. This contrasts with high-$Q$ skyrmions, whose lifetimes fall with $|Q|$ near RT. We attribute this fundamental difference between skyrmions and bimerons to their distinct magnetic texture symmetries, which lead to different entropy-dominated lifetimes.