Magnetization Switching in Single-Domain Ferromagnets

TL;DR

This paper models magnetization switching in single-domain ferromagnetic particles, emphasizing metastability and nucleation processes, and analyzes how size, boundary conditions, and interactions influence switching probability and coercivity.

Contribution

It introduces a nucleation-based approach to understand magnetization switching in finite ferromagnetic particles, considering various physical effects.

Findings

Switching probability depends on particle size and boundary conditions.

Nucleation theory effectively describes coercivity in finite systems.

Boundary conditions and interactions significantly modify switching behavior.

Abstract

A model for single-domain uniaxial ferromagnetic particles with high anisotropy, the Ising model, is studied. Recent experimental observations have been made of the probability that the magnetization has not switched. Here an approach is described in which it is emphasized that a ferromagnetic particle in an unfavorable field is in fact a metastable system, and the switching is accomplished through the nucleation and subsequent growth of localized droplets. Nucleation theory is applied to finite systems to determine the coercivity as a function of particle size and to calculate the probability of not switching. Both of these quantities are modified by different boundary conditions, magnetostatic interactions, and quenched disorder.