PHOTOEMISSION-STUDY OF ELECTRONIC-STRUCTURES OF DISORDERED NI-PT AND CU-PT ALLOYS

The valence-band photoemission spectra of disordered NixPt1-x and CuxP t1-x alloys have been measured with synchrotron radiation. Using the C ooper minimum phenomenon of the Pt 5d electron photoionization cross s ection and taking the matrix-element effect into account, we obtain ex perimental partial spectral weights (PSW's) of each constituent. For t he 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 calculation s in this case shows the importance of both relativistic effect and th e self-consistent-field treatment. For the Cu-rich Cu-Pt alloys, we fi nd 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 phot oemission study that Pt impurity forms a virtual bound state in the Cu host.