Electrical resistivity and magnetic behavior of PdNi and CuNi thin films

Electrical and magnetic properties of sputtered Pd₈₆Ni₁₄, Cu₄₆Ni₅₄, and Cu₄₂Ni₅₈ thin films have been investigated. Pd₈₆Ni₁₄ shows clear ferromagnetic properties even if magnetic clusters of 4.6μ_B are observed above the Curie-Weiss temperature, T_CW. Different magnetic properties are observed in CuNi alloys. Below T_CW, the field cooling susceptibility increases quasilinearly, while very large magnetic clusters, up to 10−12μ_B, are observed above T_CW. The temperature behavior of the resistivity of the thin films of the three alloys shows some common features. In particular, after a minimum the resistivity increases, probably due to the scattering of conduction electrons with Ni clusters. The temperature at which the minimum appears does not seem to depend on the host metal (Pd or Cu) and on the Ni concentration. These magnetic clusters affect the resistance behavior in the temperature range where the alloys are paramagnetic or close to their magnetic transition.