Direct calculation of the attempt frequency of magnetic structures using the finite element method

TL;DR

This paper introduces a finite element method-based numerical approach to calculate the attempt frequency of magnetic nanostructures using transition state theory, enabling analysis of complex shapes and media types.

Contribution

It presents a novel finite element implementation combined with the nudged elastic band method for calculating attempt frequencies in arbitrarily shaped magnetic structures.

Findings

Numerical model agrees well with analytical solutions for single domain particles.

Method applied to compare attempt frequencies in different magnetic media.

Attempt frequency is similar for different media with the same maximum anisotropy.

Abstract

A numerical implementation of the transition state theory (TST) is presented which can be used to calculate the attempt frequency $f_{0}$ of arbitrary shaped magnetic nanostructures. The micromagnetic equations are discretized using the finite element method. The climbing image nudged elastic band method is used to calculate the saddle point configuration, which is required for the calculation of $f_{0}$. Excellent agreement of the implemented numerical model and analytical solutions is obtained for single domain particles. The developed method is applied to compare $f_{0}$ for single phase and graded media grains of advanced recording media. $f_{0}$ is predicted to be comparable if the maximum anisotropy is the same in these two media types.