Domain state model for exchange bias: training effect of diluted Co1-yO on exchange bias in Co-CoO

Exchange bias in Co-CoO can be controlled and enhanced by diluting the antiferromagnetic (AFM) CoO layer with nonmagnetic defects. Here we present experiments on the dependence of exchange bias on subsequent magnetization reversals. The measurements were performed at different temperatures for samples with both low and optimum defect concentration in the AFM layer, yielding small and maximum exchange bias shift, respectively. The results are discussed within the "domain state" model for exchange bias.