Magnetocaloric effect in heterostructures of Ni$_{x}$Cu$_{(1-x)}$ alloys

We used 99.9{\%} compound targets to co-sputter Ni$_{x}$Cu$_{(1-x)}$ thin film multilayers composed of sub-layers with differing alloying compositions on silicon and oxidized silicon substrates. Each system had a Ta underlayer and capping layer. XRD was used to determine structural properties, showing a (111) preferred orientation for all Ni$_{x}$Cu$_{(1-x)}$ layers. In-Plane XRD was used to check polycrystallinity. Energy-dispersive X-ray scattering is used to determine the relative concentrations of Nickel and Copper, with XRD data corroborating the EDX results from Vegard's law. The magnetic properties of the systems are characterized and the magnetic entropies are calculated near the relevant critical temperature.