Illuminating the Multiconfigurational Ground State of Elemental and
Intermetallic Compounds of Uranium and Plutonium
SSRL Science
Summary - October 2012
The structural, electronic, and magnetic properties of U and Pu elements and
intermetallics remain poorly understood despite decades of effort, and
currently represent an important scientific frontier toward understanding
matter. The last decade has seen great progress both due to the discovery of
superconductivity in PuCoGa5 and advances in theory that finally
can explain fundamental ground state properties in elemental plutonium, such
as the phonon dispersion curve, the non-magnetic ground state, and the volume
difference between different phases of the pure element.
A new feature of the recent calculations is the presence of multiple electronic
configurations within their ground states, where the different properties of
these materials are primarily governed by the different relative weights of
these configurations. Using the new 7-crystal Johann-type spectrometer on Beam
Line 6-2 at SSRL, Corwin Booth and a team of researchers from LBNL, LANL, LLNL
and SSRL have collected resonant x-ray emission spectroscopy (RXES) data that
show, for the first time, spectroscopic signatures of each of these
configurations and their relative changes in various uranium and plutonium
materials.
In combination with conventional XANES spectra on related compounds, these data
indicate such states may be ubiquitous in uranium and plutonium intermetallics,
providing a new framework toward understanding properties ranging from heavy
fermion behavior, superconductivity, and intermediate valence to mechanical and
fundamental bonding behavior in these materials.
Work was supported by the Office of Science, Office of Basic Energy Sciences
(OBES), of the U.S. Department of Energy (DOE) under Contract No.
DE-AC02-05CH11231. X-ray data were collected at SSRL, a national user facility
operated by Stanford University on behalf of the DOE, OBES.
Primary Citation
C. H. Booth, Yu Jiang, D. L. Wang, J. N. Mitchell, P. H. Tobash, E. D. Bauer, M. A. Wall, P. G. Allen, D. Sokaras, D. Nordlund, T.-C. Weng, M. A. Torrez, and J. L. Sarrao, "Multiconfigurational nature of 5f orbitals in uranium and plutonium intermetallics", PNAS 109, 10205 (2012) [DOI: 10.1073/pnas.1200725109]Related Links
Contacts
Corwin Booth, Lawrence Berkeley National Laboratory and Tsu-Chien Weng, SSRL
