Magnetisation switching in a ferromagnetic Heisenberg nanoparticle with uniaxial anisotropy: A Monte Carlo investigation

TL;DR

This study uses Monte Carlo simulations to analyze thermally activated magnetization reversal in a ferromagnetic Heisenberg nanoparticle with uniaxial anisotropy, aiming to validate the Ne9el-Brown model at low temperatures.

Contribution

It demonstrates the application of Monte Carlo methods to reproduce magnetization reversal consistent with the Ne9el-Brown model in a cubic Heisenberg nanoparticle.

Findings

Switching field data agrees with theoretical approximation

Results align with experimental data on Co nanoparticles

Reproduction of uniform rotation reversal at low temperature

Abstract

We investigate the thermal activated magnetisation reversal in a single ferromagnetic nanoparticle with uniaxial anisotropy using Monte Carlo simulations. The aim of this work is to reproduce the reversal magnetisation by uniform rotation at very low temperature in the high energy barrier hypothesis, that is to realize the N\'eel-Brown model. For this purpose we have considered a simple cubic nanoparticle where each site is occupied by a classical Heisenberg spin. The Hamiltonian is the sum of an exchange interaction term, a single-ion anisotropy term and a Zeeman interaction term. Our numerical data of the thermal variation of the switching field are compared to an approximated expression and previous experimental results on Co nanoparticles.