Invited Paper AC+SS-MoM5
Angle-Resolved Photoemission and the 5f Electronic Structure of Pu Materials
Monday, October 18, 2010, 9:40 am, Room Isleta
| Session: |
Surface Science of Actinides |
| Presenter: |
J. Joyce, Los Alamos National Laboratory |
| Authors: |
J. Joyce, Los Alamos National Laboratory
T. Durakiewicz, Los Alamos National Laboratory
K.S. Graham, Los Alamos National Laboratory
E.D. Bauer, Los Alamos National Laboratory
J.N. Mitchell, Los Alamos National Laboratory
D.P. Moore, Los Alamos National Laboratory
J.A. Kennison, Los Alamos National Laboratory
T.M. McCleskey, Los Alamos National Laboratory
A.K. Burrell, Los Alamos National Laboratory
E. Bauer, Los Alamos National Laboratory
Q. Jia, Los Alamos National Laboratory
|
| Correspondent: |
Click to Email |
The electronic structure of Pu compounds ranging from Mott insulators to strongly correlated metals is investigated using angle-resolved photoemission (ARPES). The electronic properties of the Pu compounds PuCoGa5, PuSb2, and PuO2 are compared with angle-integrated and temperature-dependent photoemission results for Pu metal. The balance in strongly correlated materials between the central and periodic potentials is directly probed through ARPES. For the strongly correlated metals, details of the sharp quasiparticle peak at the Fermi energy are presented, including crystal momentum dispersion, giving insight into the self-energy and ground state properties of these Pu materials. In PuSb2, the ARPES data at a photon energy of 21.2 eV, indicates a quasiparticle peak that disperses through the Fermi energy. At 40.8 eV photon energy, PuSb2 shows f-electron intensity periodic with the lattice. Photoemission results for the Fermi level spectral intensity as well as the more localized 5f states well-removed from the Fermi energy are used to quantify adaptive character for these materials. Both PuSb2 and PuCoGa5 ARPES data show a dispersive peak which crosses the Fermi energy at a photon energy of 21.2 eV where the conduction states have a larger cross section than the 5f states. The results for 40.8 eV photon energy, with enhanced 5f strength, indicate a peak dispersing through the Fermi energy for PuCoGa5 but the PuSb2 data indicate an intensity modulated peak near the Fermi energy. The first ARPES results for the Mott insulator PuO2 show substantial dispersion consistent with hybrid functional calculations which predict significant covalency for PuO2 compared with the earlier ionic actinide dioxides such as UO2. The ARPES, photon energy dependence, and the temperature dependent data for Pu materials will be discussed in terms of 5f adaptive character and the implications for Pu ground state properties.
Work supported by the U.S. Department of Energy, Basic Energy Sciences, the Los Alamos National Laboratory LDRD program, and Campaign II.