Photoelectron spectroscopy study of PuCoGa5 thin films

Thin layers of PuCoGax (x = 4 to 18) have been prepared by dc sputtering from a PuCoGa5 single crystal target, and investigated in situ by X-ray and ultraviolet photoelectron spectroscopy. We could achieve broad composition variability (monitored by the Pu-4f, Co-2p and Ga-2p core-level spectra). The results are compared to the valence band spectra reported previously for PuCoGa5. Our experiments reveal that some Ga excess (PuCoGa≈7) was likely for those original data. We demonstrate that there is a tendency to the segregation of Ga at the surface, which has an important effect on the valence band spectra.