The Arrhenius Law Prefactor in Permalloy Mesoscale Systems

TL;DR

This study investigates the Arrhenius law prefactor in mesoscale ferromagnetic particles, revealing significant deviations from traditional interpretations and proposing a modified model including entropic effects.

Contribution

It introduces a modified Arrhenius model accounting for entropic contributions, explaining anomalous prefactors observed in mesoscale ferromagnetic systems.

Findings

Prefactor varies by 26 decades over barrier heights

Deviations from traditional Arrhenius interpretation observed

Modified model fits experimental data including entropic effects

Abstract

The Arrhenius equation was used to describe the dynamics of two-state switching in mesoscale, ferromagnetic particles. Using square, permalloy dots as an idealized two-state switching system, measurements of the prefactor of the Arrhenius law changed by 26 decades over barrier heights from 30 meV to 700 meV. Measurements of the prefactor ratios for a two well system revealed significant deviations from the common interpretation of the Arrhenius law. The anomalous Arrhenius prefactors and the prefactor ratios can be fitted to a modified model that includes entropic contributions to two-state transitions. Similar considerations are likely for the application of the Arrhenius law to other mesoscale systems.