On the cross-over from half-metal to normal ferromagnet in NiMnSb

Magnetism and transport properties of the semi-Heusler compound NiMnSb are re-examined in great details. A wide set of experiments (elastic and inelas tic neutron scattering, static magnetic measurements, magnetoresistance, Ha ll effect, thermopower, FMR) have been performed on polycrystals, single cr ystals or single-crystalline thin films, and the results are analysed. Spec ial emphasis is given to the magnetic excitations and to the relaxation mec hanisms in this metallic ferromagnet. At low temperatures, all experimental results hint at the existence of a fully spin-polarized conduction band (h alf metallic state). At higher temperature (T > 80 K), but well below the C urie temperature (730 K), a cross-over to a usual metallic ferromagnetic st ate is evidenced and discussed.