Resonant x-ray spectroscopy of uranium intermetallics at the U $M_{4,5}$ edges

Abstract

We present resonant x-ray emission spectroscopic (RXES) data from the uranium intermetallics UPd${}_3$, USb, USn${}_3$ and URu${}_2$Si${}_2$, at the U $M_{4,5}$ edges and compare the data to those from the well-localized $5f^2$ semiconductor UO${}_2$. The technique is especially sensitive to any oxidation of the surface, and this was found on the USb sample, thus preventing a good comparison with a material known to be $5f^3$. We have found a small energy shift between UO${}_2$ and UPd${}_3$, both known to have localized $5f^2$ configurations, which we ascribe to the effect of conduction electrons in UPd${}_3$. The spectra from UPd${}_3$ and URu${}_2$Si${}_2$,are similar, strongly suggesting a predominant $5f^2$ configuration for URu${}_2$Si${}_2$. The valence-band resonant inelastic x-ray scattering (RIXS) provides information on the U $P_3$ transitions (at about $18$~eV) between the U $5f$ and U $6p$ states, as well as transitions of between $3$ and $7$~eV from the valence band into the unoccupied $5f$ states. These transitions are primarily involving mixed ligand states (O $2p$ or Pd, Ru $4d$) and U $5f$ states. Calculations are able to reproduce both these low-energy transitions reasonably well.

11 pages, 8 figures

References in corpus (5)

• Multiconfigurational nature of 5f orbitals in uranium and plutonium intermetallics
• Spectroscopic determination of the atomic f-electron symmetry underlying hidden order in URu${}_2$Si${}_2$
• Direct bulk sensitive probe of 5f symmetry in URu2Si2
• Probing 5f-state configurations in URu2Si2 with U L3-edge resonant x-ray emission spectroscopy
• A Mean Field Model for the Quadrupolar Phases of UPd${}_3$

Cited by in corpus (2)

• Hidden order and beyond: an experimental-theoretical overview of the multifaceted behavior of URu${}_2$Si${}_2$
• f-electron charge densities probed using core level non-resonant inelastic x-ray scattering