Resistivity, Magnetoresistance, and Magnetization of Dilute Alloys of Iron inMo0.8Nb0.2

The resistivity, magnetoresistance, and magnetization have been measured for nine alloys of iron in ${\mathrm{Mo}}_{0.8}$ ${\mathrm{Nb}}_{0.2}$, with iron concentrations ranging from 0.2% to 2.3%. Minima are observed in the resistivity-versus-temperature curves in the range 28° to 38°K, depending on concentration. Both the temperature-independent impurity scattering and the spin scattering are proportional to concentration for low concentrations, and the spin resistivity is found to be a logarithmic function of the temperature. The magnetoresistance is negative in all cases, and is proportional to the square of the magnetization. These results lend support to a recent theory proposed by J. Kondo, which predicts both the linear dependence of the spin scattering on concentration and its logarithmic dependence on temperature. Using this theory, the $s-d$ exchange integral is found to be negative and equal to -0.2 eV.