Enhancing exchange bias with diluted antiferromagnets

The exchange bias H-E 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 H-E. With Co on the bottom, a thin interfacial oxide layer was primarily responsible for the strongly increased H-E.