Micromagnetic simulation of exchange coupled ferri-/ferromagnetic composite in bit patterned media

TL;DR

This study uses micromagnetic finite element simulations to explore how exchange coupling in ferri-/ferromagnetic composites can improve bit patterned media by reducing switching fields and narrowing their distribution.

Contribution

It introduces a micromagnetic model incorporating microstructural features for bilayer systems and demonstrates how exchange coupling enhances magnetic properties.

Findings

Switching field reduced by up to 40%

Switching field distribution narrowed

Optimal interface exchange coupling strength is 2 mJ/m^2

Abstract

Ferri-/ferromagnetic exchange coupled composites are promising candidates for bit patterned media because of the ability to control the magnetic properties of the ferrimagnet by its composition. A micromagnetic model for the bilayer system is presented where we also incorporate the microstructural features of both layers. Micromagnetic finite element simulations are performed to investigate the magnetization reversal behaviour of such media. By adding the exchange coupled ferrimagnet to the ferromagnet, the switching field could be reduced by up to $40\,\%$ and also the switching field distribution is narrowed. To reach these significant improvements, an interface exchange coupling strength of $2\,\mathrm{mJ/m^2}$ is required.