Exchange Anisotropy and Interlayer Exchange Coupling in fcc-NiMn/Permalloy Multilayers

Abstract

Multilayered films composed of disordered fcc-NiMn (Mn-54at.%) and Permalloy (Ni-78at. %) with fcc-[111] texture show unidirectional exchange anisotropy below 100K even when thickness of NiMn layer is 0.8nm. Disordered fcc-NiMn alloys order antiferromagnetically at low temperature and they are paramagnetic at room temperature. The unidirectional anisotropy energy at 5K for 2.0nm-thick NiMn layer is 5×10^-2erg/cm². At room temperature, magnetization curves of multilayers with 5nm-thick Permalloy layers show NiMn layer thickness dependence suggesting canted interlayer magnetic coupling through paramagnetic NiMn layers at around 2nm.