5f Electronic Structure and Fermiology of Pu Materials
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1264-Z09-04
5f Electronic Structure and Fermiology of Pu Materials John J. Joyce1, Tomasz Durakiewicz1, Kevin S. Graham1, Eric D. Bauer1, David P. Moore1, Jeremy N. Mitchell1, John A. Kennison1, T. Mark McCleskey1, Quanxi Jia1, Anthony K. Burrell1, Eve Bauer1, Richard L. Martin1, Lindsay E. Roy2, and Gustavo E. Scuseria3 1
Los Alamos National Laboratory, Los Alamos, NM 87544, U.S.A. Savannah River National Laboratory, Savannah River Site, Aiken, SC 29808, U.S.A. 3 Department of Chemistry, Rice University, Houston, TX 77005, U.S.A. 2
ABSTRACT We examine the electronic structure of δ-Pu, PuCoGa5, and PuO2 using high resolution as well as angle-resolved photoelectron spectroscopy. The fermiology of the strongly correlated metals δ-Pu and PuCoGa5 is investigated by determining the primary quasiparticle peak position with respect to the Fermi energy as well as the crystal momentum dependence of this peak for PuCoGa5. For the Mott insulator PuO2, the photoemission results are compared against hybrid functional calculations and the prediction of significant covalency, is found to be reasonable. INTRODUCTION Pu materials exhibit a remarkably broad range of properties ranging from enhanced mass and six solid state allotropes for δ-Pu, to superconductivity at 18.5 K in PuCoGa5,[1] to a large amount of covalency in PuO2 within the Mott insulator family of actinide dioxides [2] which are well described as ionic earlier in the actinide series. Central to the understanding of these electronic structure properties is an accurate picture for the characteristics of the Pu 5f electrons. There are many different ways to describe the Pu 5f interactions in a solid. The notions of hybridized/ localized, bonding/ non-bonding, magnetic/ itinerant, covalent/ ionic all capture some component of the Pu 5f levels to adapt to a specific crystalline environment with particular ligands for bonding. The adaptive character of the Pu 5f levels to different environments may also be viewed as a balance between the atomic central potential of the ionic core and the periodic potential of the solid. Within the context of periodic and central potentials, angleresolved photoelectron spectroscopy (ARPES) provides a powerful tool for determining electronic structure of materials. One may consider a quasiparticle dominated by the closest ionic core (and central potential) to be localized and most efficiently described within an atomic or localized model. Likewise, it would be reasonable to use an itinerant or hybridized description for a quasiparticle primarily under the influence of the crystalline periodic potential. In the case of Pu the interpretation of the spectroscopic data may be further complicated by strong spin-orbit interaction. [3,4] Various Pu materials cover the full range from localized in PuTe [5] and PuSb [6] to rather itinerant in α-Pu [7]. The three Pu materials covered here (δ-Pu, PuCoGa5 and PuO2) show experimental signatures one might associate with hybridized electronic structure.
For the single crystal materials (PuO2 and PuCoGa5
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