Electrical resistivity of Co-Ni-Pd and Co-Pd alloys

Three series of ferromagnetic alloys have been made: Co100−xPdx, Co25Ni75−yPdy and Co5−zNizPd95. The electrical resistivity ρ of these alloys was measured from 4 to 300 K. Their high field (H≳2 T) susceptibility χHF was obtained with superconducting quantum interference device measurements at 5 K. Comparing the residual resistivity ρ0 of Co-Ni and Co-Pd, it is found that the spin-up resistivity ρ↑ of Co-Ni follows the Nordheim’s rule, while that of Co-Pd peaks at x=85. This indicates the spin-up d band of Co-Pd is not full for all the x values. Also, χHF data reveal the same tendency of the spin-up band. Based on the deviation from Matthiessen’s rule of the two-current model, we estimate α=ρ0↓ /ρ0↑≂2 for the dilute PdCo alloy, where ρ0=ρ0↓ ρ0↑/(ρ0↑+ρ0↓ ), from the residual resistivity of the ternary Co5−zNizPd95 alloy and from the temperature dependence of ρ(T) of the binary Co5Pd95 alloy