Micromagnetic Simulation of Amorphous Ferrimagnetic TbFeCo Films with Exchange Coupled Nanophases

摘要

Amorphous ferrimagnetic TbFeCo thin films are found to exhibit exchange biaseffect near the compensation temperature by magnetic hysteresis loopmeasurement. The observed exchange anisotropy is believed to originate from theexchange interaction between the two nanoscale amorphous phases distributedwithin the films. Here, we present a computational model of phase-separatedTbFeCo using micromagnetic simulation. Two types of cells with different Tbconcentration are distributed within the simulated space to obtain aheterogeneous structure consisting of two nanoscale amorphous phases. Each cellcontains separated Tb and FeCo components, forming two antiferromagneticallycoupled sublattices. Using this model, we are able to show the existence ofexchange bias effect, and the shift in hysteresis loops is in agreement withexperiment. The micromagnetic model developed herein for a heterogeneousmagnetic material may also account for some recent measurements of exchangebias effect in crystalline films.