Electrical Resistivity ofPdFeAlloys

The electrical resistivity $\rho$ of a series of ferromagnetic $\mathrm{Pd}\mathrm{Fe}$ alloys varying in composition from 1 to 12 at.% Fe was measured from 4.2 to 300 °K. The data were analyzed by subtracting from the measured $\rho$ values, the value of the electrical resistivity of a sample of 99. 999+%-purity Pd at each temperature. From these values of the incremental resistivity $\Delta \rho$ we have obtained the temperature-dependent part by subtracting its limiting low temperature value (at 4.2-°K). The reuslting temperature- and concentration-dependent resistivity ${\rho }_m$ has the following properties: For alloys of Fe concentration $c\gtrsim 2$ at.%, ${\rho }_m\propto A{T}^2$ up to about 40 °K in all but the highest-concentration alloys studied. Above this temperature we find a $T^{\frac{3}{2}}$ law up to the ferromagnetic ordering temperature $T_C$ except in alloys with $c\gtrsim 6$ at.%, where the temperature dependence is faster above $\approx 0.7T_C$. A 1 at.% alloy sample had a low-temperature behavior intermediate between the $T^2$ behavior of the higher-concentration alloys and the $T^{\frac{3}{2}}$ behavior observed in alloys with Fe concentration less than 1 at.%. The coefficient $A$ of the low-temperature $T^2$ dependence of ${\rho }_m$ increases approximately linearly with Fe concentration, and at 2 at.% is about seven times as large as the value found in pure Pd. These results suggest that electron-magnon scattering is the dominant scattering mechanism determining ${\rho }_m$. Our data, above 2 at.% Fe, are best interpreted in terms of a model in which the $\mathrm{Pd}\mathrm{Fe}$ alloys are considered to be approximately magnetically homogeneous with an effective, concentration-dependent "$s-d$" exchange interaction. In terms of this model, the expected correlation between the coefficient $A$ and the spin-wave excitation spectrum, at low temperatures, is shown to exist.