Magnetic anisotropies and magnetotransport inCeH2/Co multilayers

Abstract

Measurements of the magnetization were performed between 4.2 and 300 K on a series of periodically stacked layers of cerium hydride and cobalt prepared by reactive ion-beam sputtering. X-ray reflectometry shows that the interfaces are sharp with a rms roughness of nominally one atomic layer. In the ground state at low temperatures, for Co-layer thicknesses up to 17 {Angstrom}, the magnetization is spontaneously oriented perpendicular to the layer planes in a multidomain configuration. A phenomenological analysis of the measured magnetic anisotropy energy reveals that the out-of-plane orientation of the magnetic easy axis is the result of a strong interface anisotropy which overcomes the shape anisotropy of the Co layers and of an additional volume anisotropy. Possible mechanisms behind the surface and volume anisotropies are discussed. Between 50 and 100 K, the magnetization turns into the layer planes in a continuous transition. The saturation magnetization, the spin-wave parameter describing its temperature dependence and the anisotropy energy vary continuously through the transition from the crystalline fcc phase to the amorphous phase of the Co sublayers near 20 {Angstrom}. This reveals the close relationship between the electronic configurations of amorphous and fcc Co. The magnetization measurements are supplemented by measurements of the anisotropicmore » magnetoresistance and the extraordinary Hall effect. The extraordinary Hall coefficient shows contributions from skew scattering and side jump processes and scales with the ordinary electrical resistivity. {copyright} {ital 1997} {ital The American Physical Society}« less