Abstract
We present low-temperature-resistivity measuremtents on five Ni1xMnx alloys (x=0.21, 0.25, 0.28, 0.30, and 0.33). Each alloy except Ni0.79 Mn0.21 exhibits a resistivity minimum which we associate with the onset of a magnetic transition from a mixed (spin-glass plus ferromagnetic order) or frustrated state towards a ferromagnetic state. This interpretation is supported by magnetoresistance data.