f-forigin of the insulating state in uranium dioxide: X-ray absorption experiments and first-principles calculations

Autor:	Jonathan C. Crowhurst, W. Siekhaus, S-W Yu, Sangeeta Sharma, Wanli Yang, James G. Tobin, J. K. Dewhurst, Paul Olalde-Velasco
Rok vydání:	2011
Předmět:	Materials science Extended X-ray absorption fine structure Absorption spectroscopy Uranium dioxide X-ray Electron Condensed Matter Physics Spectral line Electronic Optical and Magnetic Materials chemistry.chemical_compound chemistry Absorption (logic) Atomic physics Energy (signal processing)
Zdroj:	Physical Review B. 83
ISSN:	1550-235X 1098-0121
DOI:	10.1103/physrevb.83.165102
Popis:	We have performed x-ray absorption experiments on uranium dioxide (UO${}_{2}$) at the O $1s$, U $4d$, U $4f$, and U $5d$ edges. After comprehensive energy calibrations for O $1s$, U $4d$, and U $4f$ spectra, we have used the U $4d$ and $4f$ spectra to sort the energetic positions of the $5f$ and the $6d$ states in the unoccupied band unambiguously. This demonstrates conclusively that UO${}_{2}$ is an $f$-$f$ Mott-Hubbard insulator, where the electronic repulsion between $f$ electrons is responsible for the insulating state. Calculations performed within the U-corrected generalized gradient approximation of the optical response of UO${}_{2}$ permit direct comparison with the absorption spectra and confirm the experimental results.
Databáze:	OpenAIRE
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