Landau-Lifshitz-Bloch equation for exchange coupled grains

TL;DR

This paper introduces a coarse-grained model based on the Landau-Lifshitz-Bloch equation to simulate magnetization dynamics of exchange coupled grains across a wide temperature range, aiding heat-assisted magnetic recording.

Contribution

It develops a computationally efficient coarse-grained approach using the LLB equation, incorporating atomistic data for accurate temperature-dependent properties of exchange coupled grains.

Findings

The model accurately predicts magnetization behavior during heat-assisted recording.

It reduces computational effort compared to atomistic simulations.

The approach effectively captures exchange interactions between grains.

Abstract

Heat assisted recording is a promising technique to further increase the storage density in hard disks. Multilayer recording grains with graded Curie temperature is discussed to further assist the write process. Describing the correct magnetization dynamics of these grains, from room temperature to far above the Curie point, during a write process is required for the calculation of bit error rates. We present a coarse grained approach based on the Landau-Lifshitz-Bloch (LLB) equation to model exchange coupled grains with low computational effort. The required temperature dependent material properties such as the zero-field equilibrium magnetization as well as the parallel and normal susceptibilities are obtained by atomistic Landau-Lifshitz-Gilbert (LLG) simulations. Each grain is described with one magnetization vector. In order to mimic the atomistic exchange interaction between the grains a special treatment of the exchange field in the coarse grained approach is presented.