Structural,magnetic, and electrical properties of thin film Pd/Co layered structures

We report on properties of layered coherent structures of Pd and Co, prepared by RF sputtering. X-ray diffraction analysis characterizes these films as having a well-ordered periodic structure (periods λ in the range 10A < λ < 80A) of stacked (111) planes of fcc Co and Pd. Room temperature magnetic properties were measured with a vibrating sample magnetometer. All films are ferromagnetic, with a magnetic moment in excess of that attributable to Co. This excess, which increases as λ decreases, is interpreted as induced ferromagnetism in the Pd layers. The in-plane magnetization is harder for smaller values of λ and appears to depend mainly on the thickness of the Co layers. The in-plane electrical resistivity was measured in the range 2K–300K by a four-electrode method. Below 40K, the resistivity is dominated by residual resistivity; above this temperature, its rise is attributed mainly to the resistivities of bulk Pd and Co. The λ-dependence of the resistivity is described by a model of interfacial scattering of electrons. Evidence for the presence of coherency strains at small λ is present in the x-ray data, the magnetization behavior, as well as in the interfacial scattering mechanism deduced from the analysis of the resistivity.