The magnetic phase diagram and transport properties of

We have used resistivity measurements to study the magnetic phase diagram of the itinerant antiferromagnet in the temperature range from 0.3 - 300 K in magnetic fields up to 16 T. In contrast to theoretical predictions, the incommensurate spin-density-wave phase is found to be stable at least up to 16 T, with an estimated critical field of . We have also studied the low-temperature magnetoresistance in the [100], [110], and [001] directions. The transverse magnetoresistance is well described by a power law for magnetic fields above 1 T with no saturation observed at high fields. We discuss our results in terms of the magnetic structure and the calculated electronic band-structure of . We have also observed, for the first time in this compound, Shubnikov - de Haas oscillations in the transverse magnetoresistance with a frequency of for a magnetic field along [001].