Impact of higher-order exchange on the lifetime of skyrmions and antiskyrmions

TL;DR

This study demonstrates that higher-order exchange interactions significantly increase the thermal stability and lifetime of skyrmions and antiskyrmions, even in the absence of Dzyaloshinskii-Moriya interaction, by modifying energy barriers and landscape curvature.

Contribution

The paper introduces an atomistic spin model including all fourth-order exchange terms to evaluate skyrmion lifetimes, revealing the stabilizing effect of higher-order exchange interactions.

Findings

Higher-order exchange enhances skyrmion and antiskyrmion lifetimes.

Skyrmions can be thermally stable without DMI.

Tuning four-spin interactions modulates decay rates over orders of magnitude.

Abstract

Reliable control of skyrmion lifetime is essential for realizing spintronic devices, yet the role of higher-order exchange - which can lead to skyrmion stabilization - remains largely unexplored. Here we calculate lifetimes of isolated skyrmions and antiskyrmions at transition-metal interfaces based on an atomistic spin model that includes all fourth-order exchange terms. Within harmonic transition-state theory, we evaluate both energetic and entropic contributions and find substantially enhanced lifetimes when higher-order exchange is included. The four-spin four-site interaction raises the energy barrier and lowers the curvature of the energy landscape at the collapse saddle point, increasing the pre-exponential factor. We show that skyrmions and antiskyrmions can remain thermally stable even without Dzyaloshinskii-Moriya interaction (DMI), and that tuning the four-spin term by a small amount modulates the prefactor over orders of magnitude. Our results identify higher-order exchange as a promising route to stabilize topological magnetic textures - in particular in systems lacking DMI - and to engineer their thermally activated decay.