| 1. |
- Joyce, J. J., et al.
(författare)
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Dual nature of the 5f electrons in plutonium materials
- 2006
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 378-80, s. 920-924
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of select Pu materials is examined by means of photoemission (PES) and model calculations. We present the first photoemission results and electronic structure calculations for the material PuIn3. Results for Pu materials, including the cubic delta-phase metal and the superconductor PuCoGa5, give indication of the 5f electrons exhibiting both localized and itinerant character. These new results for PuIn3 place this compounds also in the 5f dual nature category. The dual nature of the Pu 5f electrons demarks the boundary between localized and itinerant 5f character in the actinides. The photoemission data for delta-Pu, PuIn3 and PuCoGa5 are compared against model calculations. The calculations are a mixed level model (MLM) which is a multi-electron extension of the generalized gradient approximation. Using the MLM, one obtains good agreement for the volume and total energy minimum with 4 of 5 Pu 5f electrons localized. The calculations also agree well with the PES spectra. Other computational schemes and interpretations are also reviewed.
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| 2. |
- Joyce, J.J., et al.
(författare)
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Photoemission and the electronic structure of PuGaCo$_5$
- 2003
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Ingår i: Physical Review Letters. ; 91, s. 176401-
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of the first Pu-based superconductor PuCoGa5 is explored using photoelectron spectroscopy and a novel theoretical scheme. Exceptional agreement between calculation and experiment defines a path forward for understanding the electronic structure aspects of Pu-based materials. The photoemission results show two separate regions of 5f electron spectral intensity, one at the Fermi energy and another centered 1.2 eV below the Fermi level. The results for PuCoGa5 clearly indicate 5f electron behavior on the threshold between localized and itinerant. Comparisons to delta phase Pu metal show a broader framework for understanding the fundamental electronic properties of the Pu 5f levels in general within two configurations, one localized and one itinerant.
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| 3. |
- Guziewicz, E., et al.
(författare)
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Angle-resolved photoemission study of dispersive and narrow-band 5f states in UAsSe
- 2006
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Ingår i: PHYSICAL REVIEW B. - 1098-0121. ; 73:15, s. 155119-
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Tidskriftsartikel (refereegranskat)abstract
- Single crystals of ferromagnetic UAsSe have been investigated by angle-resolved photoemission spectroscopy (ARPES) in the photon energy range between 20 eV and 110 eV. Electron kinetic energy intensities are collected as a function of angle and mapped onto the materials reciprocal space. Energy-band mapping has been carried out both for a several-eV-wide energy interval as well as for a narrow energy interval of less than 1 eV from the Fermi energy. The main features of the deduced energy bands can be explained by band-structure calculations. In the interval close to the Fermi energy, the very high energy and momentum resolution allows the observation of a narrow, yet dispersive photoemission peak mainly of 5f character situated within 50 meV of the Fermi energy. The Lorentzian linewidth was found to be about 35 meV with a dispersion of 30 meV along the Gamma to Z direction and 40 meV dispersion along the Gamma to X direction in the Brillouin zone. We have also found broader (linewidth about 70 meV), hybridized f-character bands with a conventional dispersion of about 1 eV along the Gamma to X and the Z to R directions in the Brillouin zone. An intriguing electronic structure emerges for UAsSe in which both relatively dispersive and narrow 5f bands are present. The occurrence of 5f-band dispersions stipulates that the electronic structure of UAsSe requires lattice periodicity to be taken into account.
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| 4. |
- Wills, J. M., et al.
(författare)
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A novel electronic configuration of the 5f states in delta-plutonium as revealed by the photo-electron spectra
- 2004
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Ingår i: Journal of Electron Spectroscopy and Related Phenomena. - : Elsevier BV. - 0368-2048 .- 1873-2526. ; 135:2-3, s. 163-166
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Tidskriftsartikel (refereegranskat)abstract
- We present a theoretical model, the mixed-level model, aiming at describing metals with very complex, strongly correlated, electronic structures. As a demonstration, it is applied to the electronic structure of delta-Pu. The model reproduces the electronic-structure related properties of this complex metal; in particular, the theory is capable of reproducing the valence band photoemission spectrum of delta-Pu. We also report new experimental photoemission spectra at several photon energies. Taken together, our results provide strong evidence that the electronic structure of delta-Pu involves a 5f shell with four electrons in a localized multiplet hybridizing with valence states, and approximately one 5f electron forming a completely delocalized band state.
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