Kerr effect observations of magnetization reversal process in antiferromagnetically pinned permalloy thin films

In this article, the magnetization reversal process for antiferromagnetic (AFM) materials (NiO, FeMn, and NiMn) coupled to NiFe permalloy thin films have been investigated. The nature of the effect of exchange coupling on the reversal of the AFM-pinned permalloy was observed using the magneto-optic Kerr effect. These studies indicated that the reversal process appears as widespread nucleation of 1–10 μm sized reversal domains over the entire area of the film with subsequent domain expansion and coalescence. Interpretation of the magnetization reversal process requires an understanding of the exchange coupling mechanism. It is believed that the magnetization reversal process observed here is dominated by a nucleation-rotation mechanism in which the interfacial spin system is highly uniform. The exact nature of the spin reversal nucleation process is not fully understood but appears to arise from weak localized pinning states.