Anisotropic magnetoresistance of Co-Pd alloys.

Abstract

The anisotropic magnetoresistance \ensuremath{\Delta}\ensuremath{\rho}/${\mathrm{\ensuremath{\rho}}}_{0}$ and electrical resistivity ${\mathrm{\ensuremath{\rho}}}_{0}$ of ${\mathrm{Co}}_{100\mathrm{\ensuremath{-}}\mathit{x}}$${\mathrm{Pd}}_{\mathit{x}}$ alloys were measured at T=4, 77, and 300 K. The temperature dependence of \ensuremath{\Delta}\ensuremath{\rho}/${\mathrm{\ensuremath{\rho}}}_{0}$ is used to yield (\ensuremath{\Delta}\ensuremath{\rho}/${\mathrm{\ensuremath{\rho}}}_{0}$${)}_{\mathrm{imp}}$ and (\ensuremath{\Delta}\ensuremath{\rho}/${\mathrm{\ensuremath{\rho}}}_{0}$${)}_{\mathrm{ph}}$ data for Co-Pd alloys as a function of x. A two-current model and theories based on extended versions of it are used to explain the spin-down resistivity ${\mathrm{\ensuremath{\rho}}}^{\mathrm{\ensuremath{\downarrow}}}$ and spin-up resistivity ${\mathrm{\ensuremath{\rho}}}^{\mathrm{\ensuremath{\uparrow}}}$. There exists a maximum in ${\mathrm{\ensuremath{\rho}}}^{\mathrm{\ensuremath{\downarrow}}}$ at x=65 at. % Pd. For x\ensuremath{\ge}50--75 at. % Pd, ${\mathrm{\ensuremath{\rho}}}_{\mathit{s}\mathit{d}}^{\mathrm{\ensuremath{\uparrow}}}$\ensuremath{\ne}0 due to the magnetic weakness for the spin-up d band. ${\mathrm{\ensuremath{\rho}}}_{\mathit{s}\mathit{s}}$ follows Nordheim's rule, and ${\mathrm{\ensuremath{\rho}}}_{\mathit{s}\mathit{s}}$ increases, going from the Co-Ni to the Co-Pd case.