Spontaneous resistivity anisotropy in nickel-copper alloys

Abstract

The longitudinal and transverse magnetoresistivity of pure nickel and its alloys containing 9.38, 18.77 and 28.32 at.% of copper were measured from room temperature to temperatures well above their Curie temperature in fields up to 10 kOe. A theory based on the well known two-current conduction model proved adequate to explain the temperature dependence observed for the spontaneous resistivity anisotropy Δ ρ_s/ ρ =( Δ rho_s/(T)- Δ ρ ⊥ s(T))/ ρ . Based on this theory, the temperature dependence of spin-up ( ρ _{spin up}ⁱ(T)) and spin-down ( ρ _{spin down}ⁱ(T)) resistivities was computed. The temperature dependence of resistivity for the two spin directions demonstrated that (i) both s-s and s-d scattering processes contribute to τ_{spin down}ⁱ(T) as contrasted with ρ_{spin up}ⁱ(T) which arises solely from s-d scattering and (ii) contribution to ρ spin downi(T) from s spin down-d spin down scattering dominates s spin down-s spin down scattering for temperatures in the immediate vicinity of room temperature, whereas the reverse situation arises for temperatures close to the Curie temperature.