RESONANT VALENCE-BAND SATELLITE IN NIGA

Valence-band photoemission spectra of NiGa were measured with synchrot oron radiation at photon energies around the Ni 3p core excitation thr eshold. The valence-band satellite in NiGa is resonantly enhanced, and it has about the same Fano parameter and effective Coulomb interactio n as those for elemental Ni. These observations suggest that the Ni d band in NiGa is not completely filled. The number of holes per Ni atom in the Ni d band for NiGa is estimated to be 0.33. The effective Coul omb interaction between two 3d holes on the same site is 4.6 eV off re sonance and 5.3 eV on resonance.