Strain effects on the fluctuation properties in noncollinear antiferromagnets: a first-principles and macrospin-based study

TL;DR

This study investigates how epitaxial strain affects magnetic fluctuation properties in Mn$_3$Sn noncollinear antiferromagnets, revealing strain-induced changes in magnetic interactions that influence thermal stability and switching behavior.

Contribution

It combines first-principles DFT calculations with macrospin simulations to elucidate the role of strain on microscopic magnetic interactions and macroscopic fluctuation properties in noncollinear antiferromagnets.

Findings

Strain significantly alters magnetic anisotropy and exchange interactions.

Biquadratic exchange is crucial in the magnetic energy landscape.

Strain impacts energy barriers and magnetic fluctuation rates.

Abstract

We present a theoretical investigation of epitaxial strain effects on the magnetic fluctuation properties of Mn$_3$Sn noncollinear antiferromagnets. Employing density functional theory (DFT), we uncover significant strain-induced modifications to key magnetic parameters, including magnetic anisotropy and both bilinear and biquadratic exchange interactions. Our findings reveal that the biquadratic exchange, often neglected, plays a crucial role in defining the magnetic energy landscape and its response to strain. These microscopic changes directly impact the energy barriers governing magnetic switching, thereby influencing thermal stability and fluctuation rates. Using macrospin-based simulations based on DFT-derived parameters, we provide a quantitative analysis of the macroscopic magnetic fluctuations influenced by these microscopic interactions. These insights are particularly relevant for applications requiring precisely controlled magnetic behavior, such as hardware for probabilistic computing.