Electronic structures of the half-metallic Heusler alloys: NiMnSb and PtMnSb

Abstract

Electronic structures of the Heusler alloys of NiMnSb and PtMnSb, which have been predicted to be half-metallic ferromagnetic, are investigated by using photoemission spectroscopy (PES). The PES spectral weight distributions for the Mn 3 d, Ni 3 d, and Pt 5 d states are extracted experimentally and compared with the angular momentum projected local density of states (PLDOS) from the local density functional band structure calculations. It is found that the Mn 3 d character spreads throughout the valence band, and that the Ni 3 d and Mn3 d states overlap each other throughout the Ni 3 d bands, suggesting substantial hybridization between Mn 3 d and Ni 3 d states. For NiMnSb, a Ni 3 d satellite feature is observed about 6 eV below the main valence band, reflecting the correlation effects among the Ni 3 d electrons. The comparison of the measured PES spectra to the calculated PLDOS shows substantial discrepancies between experiment and theory for both NiMnSb and PtMnSb.