Theoretical Investigation of Exchange Bias in Compensated Cases

摘要

The exchange bias(EB)of the ferromagnetic(FM)/antiferromagnetic(AFM)bilayers in a compensated caseis studied by use of the many-body Green's function method of quantum statistical theory.The so-called compensatedcase is that there is no net magnetization on the AFM side of the interface.Our conclusion is that the EB in this case isprimarily from the asymmetry of the interracial exchange coupling strengths between the FM and the two sublattices ofthe AFM.The effects of the layer thickness,temperature and the interfacial coupling strength on the exchange bias H_Eare investigated.The dependence of H_E on the FM layer thickness and temperature is qualitatively in agreement withexperimental results.H_E is nearly inversely proportional to FM thickness.When temperature varies,both HE and H_Cdecrease with temperature increasing.The anisotropy of the FM layer only slightly influence H_C,but does not influenceH_E.