Enhancing exchange bias with diluted antiferromagnets

The exchange bias HE of coupled polycrystalline films of antiferromagnetic CoO and ferromagnetic Co was significantly enhanced by the systematic substitution of nonmagnetic Mg for Co in CoO. Samples in which either Co or Co1-xMgxO were deposited first were investigated at temperatures from 10 to 300 K. With Co1-xMgxO on the bottom, the increased interfacial uncompensated spin density of the single antiferromagnetic domain Co1-xMgxO crystallites produced the enhanced HE. With Co on the bottom, a thin interfacial oxide layer was primarily responsible for the strongly increased HE.