# Stability of Long-lived Antiskyrmions in Mn-Pt-Sn Material

## TL;DR

This study calculates the room-temperature lifetime of antiskyrmions in Mn-Pt-Sn, revealing their exceptional stability due to large activation energy, with results aligning with experimental observations.

## Contribution

It introduces an atomic scale modeling approach with harmonic transition state theory to accurately predict antiskyrmion stability in Mn-Pt-Sn.

## Key findings

- Long antiskyrmion lifetime at room temperature confirmed
- Stability driven by large activation energy from strong exchange coupling
- Pre-exponential factor remains typical despite large system size

## Abstract

The lifetime of antiskyrmions at room temperature in a Mn-Pt-Sn tetragonal Heusler material has been calculated using an atomic scale representation including nearly a million spins. The evaluation of the pre-exponential factor in the Arrhenius rate expression for this large system is made possible by an implementation of harmonic transition state theory that avoids evaluation of the eigenvalues of the Hessian matrix.The parameter values in the extended Heisenberg Hamiltonian, including anisotropic Dzyaloshinskii-Moriya interaction, are chosen to reproduce experimental observations [A. K. Nayak $\it{et\,al.}$, Nature $\textbf{548}$, 561 (2017)], in particular the 150 nm diameter. The calculated results are consistent with the long lifetime observed in the laboratory and this exceptional stability of the antiskyrmions is found to result from large activation energy for collapse due to strong exchange coupling while the pre-exponential factor in the Arrhenius expression for the lifetime is found to have a typical magnitude of 10$^{-12}$ s, despite the large number of spins. The long lifetime is, therefore, found to result from energetic effects rather than entropic effects in this system.