Ferromagnetic resonance studies of exchange biasing in Ni81Fe19/Pt10Mn90 bilayers

Abstract

In-plane ferromagnetic resonance (FMR) has been used to study exchange anisotropy in Ni81Fe19/Pt10Mn90 bilayers at room temperature. A theoretical calculation for the FMR resonance field was carried out based on a simple model of the exchange bias in a polycrystalline bilayer that incorporates reversible as well as irreversible behavior of the antiferromagnetic layer. In addition to the expected cos φH contribution to the resonance field, where φH is the direction of the applied field, there is a negative shift of the resonance field. It is argued that the negative shift of the resonance related to the irreversible behavior of the antiferromagnetic moments is not isotropic. The linewidth broadening of in-plane resonance for the exchange biased bilayers is also discussed.