VALENCE-BAND AND SB 4D CORE-LEVEL PHOTOEMISSION OF THE XMNSB-TYPE HEUSLER COMPOUNDS (X=PT, PD, NI)

Abstract

Electronic structures of the valence band and Sb 4d core levels of the XMnSb-type Heusler alloys (where X = Pt, Pd, Ni) have been investigated systematically using photoemission spectroscopy (PES) and self-consistent spin-polarized band structure calculations. The extracted Mn 3d PSW of XMnSb (where X = Pt, Pd) are found to be almost identical. Interestingly, they are quite different from those of Mn metal, but are analogous to those of MnO, suggesting that the role of the Sb 5p electrons in XMnSb may be similar to that of the O 2p electrons in MnO. A comparison of the PSW with the corresponding theoretical angular momentum projected density of states (PLDOS) shows a fairly good agreement for the Pt and Pd d states, but large discrepancies for the Mn and Ni 3d states. The calculated X d and Mn 3d PLDOS reveal that the hybridization between the Mn 3d and X d states increases from X = Pt to Pd and Ni. In the Sb 4d core level PES spectra, a broader and less structureless line shape is observed for X = Pd than for X = Pt and Ni. A detailed analysis of their line shapes indicates that it is due to a larger lifetime broadening for X = Pd than for X = Pt and Ni.