Perpendicular magnetization and exchange bias in epitaxial Cu∕Ni∕Fe₅₀Mn₅₀ thin films

The perpendicular magnetic anisotropy has been achieved in epitaxial Cu∕Ni thin films deposited by magnetron sputtering. A thin Fe₅₀Mn₅₀ layer deposited on top of the Ni layer induces perpendicular exchange bias arising from the interface exchange coupling. The hysteresis loops, the ferromagnetic thickness dependence, and the angular dependence of the exchange bias in as-deposited and field-cooled Cu∕Ni∕Fe₅₀Mn₅₀ trilayer thin films have been investigated. This study reveals many interesting features that are much different from those of in-plane exchange biased systems. It suggests distinct magnetization reversal behavior, domain nucleation, and domain wall motion of the Ni layer in the presence of interface coupling with Fe₅₀Mn₅₀, which deserves further study.