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تسجيل مستخدم جديدBulk 5f electronic states in uranium monochalcogenide US
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We have investigated the electronic states of the uranium monochalcogenide US, which is a typical ferromagnetic uranium compound, using soft x-ray photoemission spectroscopy (SX-PES). In early ultraviolet photoemission spectroscopy studies, two peak structures of the U 5f states were observed and have been interpreted that one has an itinerant character around the Fermi level (EF) and the other located below EF has a character of localized U 5f electrons. In this study, the intrinsic bulk valence-band spectrum of US was first deduced by estimating the contribution of surface states to the valence-band spectrum using core-level photoemission spectra. We conclude that the electronic structure of US can be basically described by the itinerant nature of the U 5f electrons from comparison with theoretical valence-band spectra obtained by band-structure calculation in the local-density approximation.
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We study the spin-dependent electronic structure of UTe and UT_{2}Si_{2} (T=Cu and Mn) compounds with a combination of x-ray magnetic circular dichroism measurements and first principle calculations. By exploiting the presence of sizable quadrupolar
and dipolar contributions to the U L_{2,3}-edge x-ray absorption cross section we are able to provide unique information on the extent of hybridization between 5f and 6d/3d electronic states, a key parameter regulating the physical properties of all actinide materials. Since this information is hardly accessible to other probes, the new methodology opens up new venues for investigating this important class of materials.
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Uranium and plutoniums 5f electrons are tenuously poised between strongly bonding with ligand spd-states and residing close to the nucleus. The unusual properties of these elements and their compounds (eg. the six different allotropes of elemental pl
utonium) are widely believed to depend on the related attributes of f-orbital occupancy and delocalization, for which a quantitative measure is lacking. By employing resonant x-ray emission spectroscopy (RXES) and x-ray absorption near-edge structure (XANES) spectroscopy and making comparisons to specific heat measurements, we demonstrate the presence of multiconfigurational f-orbital states in the actinide elements U and Pu, and in a wide range of uranium and plutonium intermetallic compounds. These results provide a robust experimental basis for a new framework for understanding the strongly-correlated behavior of actinide materials.
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