Soft magnetic properties of amorphous-CoZr/ polycrystalline-M (M = Cu, Ag, Al, Cr) multilayers

This study examines the microstructures and magnetic properties of (CoZr10 nm/M10 nm)20 (M=Cu, Ag, Al, Cr) multilayers prepared by direct current magnetron sputtering. The structural characterizations show that CoZr layers have an amorphous structure, but a slight dissimilarity of local structure exists among the amorphous phases, which is most likely affected by the different polycrystalline M layers. Consequently, the soft magnetic properties of (CoZr10 nm/M10 nm)20 multilayers are strongly dependent on the non-magnetic M layers. On the other hand, an in-plane uniaxial magnetic anisotropy is observed for all multilayers, which can be attributed to the tensile stress induced by sample rotation during film deposition. A combination of Cu serving as non-magnetic layers and tensile stress is the key to enhancing the soft magnetic properties of CoZr-based films. The mechanisms responsible for the dependence of the magnetic properties on non-magnetic M layers and tensile stress are discussed.