A model of the magnetic properties of coupled ferromagnetic∕antiferromagnetic bilayers

A granular level model which is capable of predicting the bulk magnetic properties of coupled ferromagnetic and antiferromagnetic layers is described. The model is used in an extensive investigation of the effect of the thermal instability of the antiferromagnetic layer as a function of the layer thickness, grain diameter, temperature, and the grain size distribution σ. The calculations give good qualitative agreement with experiment and provide an understanding of the role of the antiferromagnetic layer in determining the exchange bias field and the coercivity.