Thermal fluctuations in antiferromagnetic nanostructures

TL;DR

This paper presents a theoretical model for analyzing thermal fluctuations in antiferromagnetic nanostructures, offering insights into their stability and stochastic dynamics.

Contribution

A novel Fourier series-based theoretical approach for accurately modeling thermal fluctuations in AFM nanoparticles, improving upon previous micro-magnetic simulation methods.

Findings

AFM states are more thermally stable than ferromagnetic states.

The model accurately predicts spontaneous Néel vector switching behavior.

AFM nanostructures exhibit longer retention times due to reduced thermal flipping.

Abstract

A theoretical model is developed that can accurately analyze the effects of thermal fluctuations in antiferromagnetic (AFM) nano-particles. The approach is based on Fourier series representation of the random effective field with cut-off frequencies of physical origin at low and high limits while satisfying the fluctuation-dissipation theorem at the same time. When coupled with the formalism of a Langevin dynamical equation, it can describe the stochastic N\'eel vector dynamics with the AFM parameters, circumventing the arbitrariness of the commonly used treatments in the micro-magnetic simulations. Subsequent application of the model to spontaneous N\'eel vector switching provides a thermal stability analysis of the AFM states. The numerical simulation shows that the AFM states are much less prone to the thermally induced accidental flips than the ferromagnetic counterparts, suggesting a longer retention time for the former.