Spin-dependent electrical transport in ion-beam sputter deposited Fe-Cr multilayers

The temperature dependence of the electrical resistivity and magnetoresistance of Xe-ion-beam-sputtered Fe-Cr multilayers has been investigated. The electrical resistivity between 5 and 300 K in the fully ferromagnetic state, obtained by applying a field beyond the saturation field (Hₛₐₜ) necessary for the antiferromagnetic- (AF-) ferromagnetic (FM) field-induced transition, shows evidence of spin-disorder resistivity as in crystalline Fe and an s-d scattering contribution (as in $3d$ metals and alloys). The sublattice magnetization $m(T)$ in these multilayers has been calculated in terms of the planar and interlayer exchange energies. The additional spin-dependent scattering Δρ(T)=ρ(T,H=0)AF-ρ(T,H=Hₛₐₜ)FM in the AF state over a wide range of temperature is found to be proportional to the sublattice magnetization, both Δρ(T) and $m(T)$ reducing along with the antiferromagnetic fraction. At intermediate fields, the spin-dependent part of the electrical resistivity [ρₛ(T)] fits well to the power law ρₛ(T)=b-cT^α where c is a constant and b and {α} are functions of H. At low fields α2 and the intercept b decreases with H much the same way as the decrease of Δρ(T) with T. A phase diagram (T vs Hₛₐₜ) is obtained for the field-induced AF-to-FM transition. Comparisons are made between the present investigation and similar studies using dc-magnetron-sputtered and molecular-beam-epitaxy-grown Fe-Cr multilayers.