Control of exchange bias by diluting the antiferromagnetic layer

The domain state model for exchange bias is used for an investigation of recent experiments where the magnitude and direction of the exchange bias was controlled by He ion irradiation of an FeNi/FeMn sample. The defects in the sample which result from the irradiation are modeled as diluting the antiferromagnet ~AFM! after the initial cooling procedure. This late dilution, carried out in presence of a field leads to a rearrangement of the original domain structure of the AFM resulting in an enhancement or reduction in the bias field