Magnetization switching in nanoscale ferromagnetic grains: description by a kinetic Ising model

TL;DR

This paper models the magnetization switching in nanoscale ferromagnetic grains using a kinetic Ising model, combining droplet theory and Monte Carlo simulations to understand experimental observations of magnetic state changes.

Contribution

It introduces a kinetic Ising model approach to describe magnetization switching in nanoscale grains, emphasizing finite size effects and droplet nucleation mechanisms.

Findings

Qualitative agreement with experimental switching behavior

Finite size effects influence magnetization dynamics

Droplet nucleation and growth explain switching mechanisms

Abstract

The magnetic relaxation of ferromagnetic powders has been studied for many years, largely due to its importance to recording technologies. However, only recently have experiments been performed that resolve the magnetic state of individual sub-micron particles. Motivated by these experimental developments, we use droplet theory and Monte Carlo simulations to study the time and field dependence of some quantities that can be observed by magnetic force microscopy. Particular emphasis is placed on the effects of finite particle size. The qualitative agreement between experiments on switching and our simulations in individual single-domain ferromagnets suggests that the switching mechanism in such particles may involve local nucleation and subsequent growth of droplets of the stable phase.