Electronic structure of α- and δ-Pu from photoelectron spectroscopy

Arko, A. J.; Joyce, John J.; Morales, Luis; Wills, J. M.; Lashley, J. C.; Wastin, F.; Rébizant, J.

doi:10.1103/physrevb.62.1773

Cited by 141 publications

(156 citation statements)

References 17 publications

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“…The susceptibility is small and relatively temperature independent. The photoemission 117 shows a strong narrow Kondo-like peak at the Fermi level consistent with large values of the linear specific heat coefficient.…”

Section: Dynamical Mean Field Approach and The Regime Of Strong supporting

confidence: 55%

Electronic Structure and Magnetic Properties of Solids

et al. 2005

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Section: Dynamical Mean Field Approach and The Regime Of Strong supporting

confidence: 55%

Electronic Structure and Magnetic Properties of Solids

et al. 2005

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“…8 Theoretical model for intermediate coupling scheme was suggested for PuSb by Cooper et al 9 Many experiments have been carried out to shed light on plutonium electronic structure. For δ-plutonium, most investigated of all metallic Pu phases, photoemission spectroscopy (PES) revealed special features of valence band 10,11,12 in particular a sharp peak at the Fermi level. X-ray, high-resolution ultraviolet, 13 and resonant photoemission 14 spectroscopy measurements accompanied with Pu 4f core-level spectra show more localized character of 5f electrons in δ-Pu phase comparing with α phase.…”

Section: Introductionmentioning

confidence: 99%

Magnetic state and electronic structure of theδandαphases of metallic Pu and its compounds

et al. 2005

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By LDA+U method with spin-orbit coupling (LDA+U+SO) the magnetic state and electronic structure have been investigated for plutonium in δ and α phases and for Pu compounds: PuN, PuCoGa5, PuRh2, PuSi2, PuTe, and PuSb. For metallic plutonium in both phases in agreement with experiment a nonmagnetic ground state was found with Pu ions in f 6 configuration with zero values of spin, orbital, and total moments. This result is determined by a strong spin-orbit coupling in 5f shell that gives in LDA calculation a pronounced splitting of 5f states on f 5/2 and f 7/2 subbands. A Fermi level is in a pseudogap between them, so that f 5/2 subshell is already nearly completely filled with six electrons before Coulomb correlation effects were taken into account. The competition between spin-orbit coupling and exchange (Hund) interaction (favoring magnetic ground state) in 5f shell is so delicately balanced, that a small increase (less than 15%) of exchange interaction parameter value from JH = 0.48 eV obtained in constrain LDA calculation would result in a magnetic ground state with nonzero spin and orbital moment values. For Pu compounds investigated in the present work, predominantly f 6 configuration with nonzero magnetic moments was found in PuCoGa5, PuSi2, and PuTe, while PuN, PuRh2, and PuSb have f 5 configuration with sizeable magnetic moment values. Whereas pure jj coupling scheme was found to be valid for metallic plutonium, intermediate coupling scheme is needed to describe 5f shell in Pu compounds. The results of our calculations show that exchange interaction term in the Hamiltonian must be treated in a general matrix form for Pu and its compounds.

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“…Pu defines the localized/itinerant boundary for the 5f electrons in the actinides [4,5]. There have been several recent papers reporting photoemission [6,8,7,9] and electronic structure calculations [4,5,10,11,12,13,14] for the fcc (δ ) phase of Pu metal. A classic failure of density functional theory (DFT) within the local density approximation (LDA) or generalized gradient approximation (GGA) is observed in the case of δ -Pu with the volume from LDA falling over 25% short (GGA only slightly better) of the experimental volume in the largest discrepancy to date in DFT for a crystal.…”

Section: Introductionmentioning

confidence: 99%

“…The sample surface was cleaned by laser ablation at a temperature (T) of 77 K in a vacuum of 6x10 -11 Torr. Laser ablation has been shown to be an excellent choice of surface preparation for actinides [7,6]. There were no spectroscopic features identifiable as surface-related in the staged cleaning of the sample surface from native oxide through clean metallic surface.…”

Section: Introductionmentioning

confidence: 99%

“…There were no spectroscopic features identifiable as surface-related in the staged cleaning of the sample surface from native oxide through clean metallic surface. There was no sample surface contamination in the spectra with the 40.8 eV data having a sensitivity of about five percent of a monolayer for oxide-related degradation [8,6]. The UV light source utilizes the He I (21.2 eV) He IIα (40.8 eV) and He IIβ (48.4 eV) lines.…”

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Photoemission and the Electronic Structure ofPuCoGa5

et al. 2003

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The electronic structure of the first Pu-based superconductor PuCoGa 5 is explored using photoelectron spectroscopy and a novel theoretical scheme. Exceptional agreement between calculation and experiment defines a path forward for understanding 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 PuCoGa 5 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. PACS: 71.27.+a,71.28.+d, The recent discovery of PuCoGa 5 , the first Pu-based superconductor, with a T C =18.5 K and unconventional superconductivity demonstrates the rich and complex nature of Pu-based materials [1]. The role of the 5f electrons in bonding and hybridization is intimately intertwined with the wide range of ground state properties found in actinide materials including enhanced mass, magnetism, superconductivity, as well as spin and charge density waves. Within the actinide series, Pu occupies the position between the clearly hybridized 5f states of uranium [2] and clearly localized 5f states of americium[3] which due to its J=0 ground state is a superconductor. Pu defines the localized/itinerant boundary for the 5f electrons in the actinides [4,5]. There have been several recent papers reporting photoemission [6,8,7,9] and electronic structure calculations [4,5,10,11,12,13,14] for the fcc (δ ) phase of Pu metal. A classic failure of density functional theory (DFT) within the local density approximation (LDA) or generalized gradient approximation (GGA) is observed in the case of δ -Pu with the volume from LDA falling over 25% short (GGA only slightly better) of the experimental volume in the largest discrepancy to date in DFT for a crystal.To accommodate the large volume of the delta phase of Pu metal, there have been magnetically ordered electronic structures proposed which, to some degree, effectively localize 5f electrons, reducing the contribution to the chemical bonding and increasing the volume[10], however there is no experimental evidence for magnetism in δ -Pu [15]. Another approach used for δ -Pu is the dynamical mean field theory (DMFT) which may offer promise with further development [11]. Currently the agreement between DMFT and experiment is weak with the PES shown in Ref.[11] being more of an idealized representation than actual data. The link between δ -Pu metal and PuCoGa 5 is strong and follows the same path as the family of Ce-based heavy fermion-superconductors (CeMIn 5 , M=Co, Rh, Ir) [16] having the cubic CeIn 3 as the root crystal structure. Here we have δ -Pu as the parent cubic phase structure with Ga substituting on the face centers to form PuGa 3 and insertion of the CoGa 2 layer into the cubic s...

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Electronic structure of α- and δ-Pu from photoelectron spectroscopy

Cited by 141 publications

References 17 publications

Electronic Structure and Magnetic Properties of Solids

Electronic Structure and Magnetic Properties of Solids

Magnetic state and electronic structure of theδandαphases of metallic Pu and its compounds

Photoemission and the Electronic Structure ofPuCoGa5

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