Micromagnetic Simulation of Nanoscale Films with Perpendicular Anisotropy

TL;DR

This paper presents a Monte Carlo simulation model for nanoscale magnetic films with perpendicular anisotropy, capturing domain wall dynamics, hysteresis, and thermal effects to explain experimental observations.

Contribution

It introduces a comprehensive model combining exchange, dipolar forces, disorder, and thermal effects to study magnetic domain behavior in nanoscale films.

Findings

Hysteresis in thin films can be modeled as a depinning transition.

Domain wall velocity depends on field and temperature, showing thermal activation effects.

The model explains experimental magnetization reversal phenomena.

Abstract

A model is studied for the theoretical description of nanoscale magnetic films with high perpendicular anisotropy. In the model the magnetic film is described in terms of single domain magnetic grains with Ising-like behavior, interacting via exchange as well as via dipolar forces. Additionally, the model contains an energy barrier and a coupling to an external magnetic field. Disorder is taken into account in order to describe realistic domain and domain wall structures. The influence of a finite temperature as well as the dynamics can be modeled by a Monte Carlo simulation. Many of the experimental findings can be investigated and at least partly understood by the model introduced above. For thin films the magnetisation reversal is driven by domain wall motion. The results for the field and temperature dependence of the domain wall velocity suggest that for thin films hysteresis can be described as a depinning transition of the domain walls rounded by thermal activation for finite temperatures.