Magnetoresistance anisotropy in ferromagnetic NiCu alloys

The magnetoresistance anisotropy is calculated for ferromagnetic nickel-copper alloys. The model is based on $\mathrm{sd}$ impurity scattering at temperatures sufficiently low for the electron-magnon interaction to be negligible. The $d$ bands as well as the conductivity integrals are treated in considerably more detail than previously reported. The results indicate that the majority-spin current favors the condition ${\rho }_{\parallel }<{\rho }_{\perp }$ and the minority-spin current favors ${\rho }_{\parallel }>{\rho }_{\perp }$. This is in opposition to previous work based on overly simplified band models. The feature of the band models. The feature of the band structure most responsible for producing a large, positive, magnetoresistance coefficient $\frac{({\rho }_{\parallel }-{\rho }_{\perp })}{{〈\rho 〉}_{\mathrm{av}}}$ appears to be a near-degeneracy at the Fermi energy between predominantly minority-spin bands.