Hybrid exchange bias in (FePt-FeMn)N multilayers

A systematic study of exchange bias for both the perpendicular and in-plane magnetization processes in (FePt-FeMn)_N multilayers is presented. Multilayers of (FePt-FeMn)_N were deposited onto MgO(100) substrates by an ion beam sputtering system. The dependence of in-plane and out-of-plane exchange bias fields (H_E) and coercive fields (H_C) on the thicknesses of both FePt and FeMn shows that exchange bias in multilayers has an interface characteristic and the theoretical model involving perpendicular domain walls in the antiferromagnetic layers appears to be a plausible explanation. The established exchange bias in any direction indicates that exchange bias can be induced regardless of the field cooling direction.