Dependence of training effect on the antiferromagnetic structure of exchange-bias bilayers within the domain-state model

The influence of the antiferromagnetic thickness and dilution on the training effect is investigated with the use of an atomistic model for the magnetic interaction for constant temperature. We analyze the phenomenology in both ferromagnet and antiferromagnet in terms of hysteresis loop quantities and stable spin populations during training. While for small antiferromagnetic layer thicknesses we observe thermal training, an increase in the AFM thickness leads to athermal training. In contrast an increase in the AFM dilution leads to athermal training, while in low dilution we observe thermal training. At a value of dilution in the range of 30-40%, we observe the largest exchange-bias field with the smallest training effect. The domain structure of the antiferromagnet changes rapidly with dilution, which is shown to give large changes in the training effect.