ELECTRONIC-STRUCTURES OF THE HALF-METALLIC HEUSLER ALLOYS - NIMNSB AND PTMNSB

Electronic structures of the Heusler alloys of NiMnSb and PtMnSb, whic h have been predicted to be half-metallic ferromagnetic, are investiga ted by using photoemission spectroscopy (PES). The PES spectral weight distributions for the Mn 3d, Ni 3d, and Pt 5d states are extracted ex perimentally and compared with the angular momentum projected local de nsity of states (PLDOS) from the local density functional band structu re calculations. It is found that the Mn 3d character spreads througho ut the valence band, and that the Ni 3d and Mn3d states overlap each o ther throughout the Ni 3d bands, suggesting substantial hybridization between Mn 3d and Ni 3d states. For NiMnSb, a Ni 3d satellite feature is observed about 6 eV below the main valence band, reflecting the cor relation effects among the Ni 3d electrons. The comparison of the meas ured PES spectra to the calculated PLDOS shows substantial discrepanci es between experiment and theory for both NiMnSb and PtMnSb.