Photoemission study of electronic structures of disordered Ni-Pt and Cu-Pt alloys

The valence-band photoemission spectra of disordered (Formula presented)(Formula presented) and (Formula presented)(Formula presented) alloys have been measured with synchrotron radiation. Using the Cooper minimum phenomenon of the Pt 5d electron photoionization cross section and taking the matrix-element effect into account, we obtain experimental partial spectral weights (PSW’s) of each constituent. For the Ni-rich Ni-Pt alloys, we find substantial weights of the Pt states near the Fermi level, which are believed to be responsible for the Pt local magnetic moment. The comparison with the theoretical calculations in this case shows the importance of both relativistic effect and the self-consistent-field treatment. For the Cu-rich Cu-Pt alloys, we find that due to the strong hybridization Cu 3d and Pt 5d states form a common band. This calls into question the conclusion of the early photoemission study that Pt impurity forms a virtual bound state in the Cu host.