Temperature dependence of magnetoresistance in the ${\mathrm{Ni}}_3$Al system

The transverse magnetoresistance of stoichiometric and off-stoichiometric polycrystalline samples of the ${\mathrm{Ni}}_3$Al system has been measured over the temperature range $1.2<T<\mathrm{}90\mathrm{}$ K in magnetic fields up to 23 kOe. Negative magnetoresistance was observed in all cases. In samples with Ni concentrations of 75 at.% or greater the magnitude of the magnetoresistance reached a maximum at $T=T_C$. The data are in qualitative agreement with the theoretical predictions of Chang et al. based on a model of the magnetoresistance of an itinerant ferromagnet, but the observed magnetoresistance is considerably larger than predicted.