Computer Simulations of Thermal Switching in Small-grain Ferromagnets

TL;DR

This paper uses Monte Carlo and micromagnetic simulations to analyze thermal switching mechanisms in small ferromagnetic particles, revealing different reversal behaviors depending on external conditions and showing an outside-in reversal mode in Ni pillar arrays.

Contribution

It introduces combined Monte Carlo and micromagnetic approaches to study thermal switching, highlighting regime-dependent behaviors and reversal modes in small ferromagnetic systems.

Findings

Switching probability varies with field, temperature, and size.

Different reversal mechanisms dominate in different regimes.

Reversal in Ni pillars starts at the perimeter (outside-in mode).

Abstract

We present Monte Carlo and Langevin micromagnetic calculations to investigate thermal switching of single-domain ferromagnetic particles. For the Monte Carlo study we place particular emphasis on the probability that the magnetization does not switch by time t. We find that this quantity has different behaviors in different regimes of applied field, temperature, and system size, and we explain this in terms of different reversal mechanisms that dominate in the different regimes. In the micromagnetic study of an array of Ni pillars, we show that the reversal mode is an outside-in mode starting at the perimeter of the array of pillars.