Electronic Structure of PuCoGa 5 and UCoGa 5

The electronic structure of the Pu-based superconductor PuCoGa 5 and the Pauli paramagnet UCoGa 5 is investigated using photoemission spectroscopy. The photoemission data of PuCoGa 5 reveal features at the Fermi energy EF and about 1-1.5 eV below EF indicative of itinerant and localized f-electrons, respectively. Angle-resolved spectra of UCoGa 5 show two peaks at similar energies that are highly dispersive, providing evidence for itinerant character of the f-electrons in this material. A comparison of the PuCoGa 5 and UCoGa 5 data to the spectra of α-Pu and δ-Pu serves to place PuCoGa 5 within the context of the more general electronic structure problem in elemental Pu.