Spin susceptibility of Ga-stabilized<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:mi>δ</mml:mi><mml:mtext>−</mml:mtext><mml:mi mathvariant="normal">Pu</mml:mi></mml:mrow></mml:math>probed by<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi mathvariant="normal">Ga</mml:mi><mml:mprescripts /><mml:none /><mml:mn>69</mml:mn></mml:mmultiscripts></mml:math>NMR

Piskunov, Yu. V.; Михалев, К. Н.; Gerashenko, A.; Pogudin, A.; Ogloblichev, V. V.; Verkhovskiǐ, S. V.; Tankeyev, A. P.; Архипов, В. Е.; Zouev, Yu.N.; Lekomtsev, Sergey

doi:10.1103/physrevb.71.174410

Cited by 26 publications

(11 citation statements)

References 17 publications

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“…In the present study, we comment on a very few published works in the literature. At this point, the experimental evidence for the magnetic moment of δ‐Pu remains fairly conclusive 10, 23, 24. Susceptibility and resistivity data for δ‐Pu were published by Meot–Reymond and Fournier 23, indicating the existence of small magnetic moments screened at low temperatures.…”

Section: Theory and Computational Detailsmentioning

confidence: 79%

“…Piskunov et al 24 studied the spin susceptibility of the stabilized δ phase in the Pu–Ga alloy by measuring 69,71 Ga nuclear magnetic resonance (NMR) spectra and the nuclear spin‐lattice relaxation rate within the temperature range 5–350 K. No NMR evidence favoring formation of the static magnetic order in δ‐Pu was revealed down to 5 K. Although there is no direct experimental evidence of magnetic moment, spin‐polarized DFT, specifically the GGA‐DFT, has been used by theoreticians, in particular, to predict the magnetic ordering and ground‐state properties of δ‐Pu 25–30. This is partly because spin‐polarized DFT calculations do predict better agreement with photoemission data, as well as atomic volume and bulk modulus 22.…”

Section: Theory and Computational Detailsmentioning

confidence: 99%

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Ab initio study of molecular oxygen adsorption on Pu (111) surface

Huda

Ray

2005

Int J of Quantum Chemistry

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ABSTRACT:Using the generalized gradient approximation to density functional theory (DFT), molecular and dissociative oxygen adsorptions on a Pu (111) surface has been studied in detail. Dissociative adsorption with a layer-by-layer alternate spin arrangement of the plutonium layer is found to be energetically more favorable, and adsorption of oxygen does not change this feature. Hor1 (O 2 is parallel to the surface and lattice vectors) approach on the center2 (center of the unit cell, where there is a Pu atom directly below on the third layer) site, both without and with spin polarization, was found to be the preferred chemisorbed site among all cases studied with chemisorption energies of 8.365 and 7.897 eV, respectively. The second-highest chemisorption energy occurs at the Ver (O 2 is vertical to the surface) approach of the bridge site with chemisorption energies of 8.294 eV (non-spin-polarized) and 7.859 eV (spin-polarized), respectively. We find that 5f electrons are more localized in the spinpolarized case than the non-spin-polarized counterparts. Localization of the 5f electrons is higher in the oxygen-adsorbed plutonium layers compared with the bare layers. The ionic part of OOPu bonding plays a significant role in the chemisorption process, along with Pu 5fOO 2p hybridization.

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Section: Theory and Computational Detailsmentioning

confidence: 79%

Section: Theory and Computational Detailsmentioning

confidence: 99%

Ab initio study of molecular oxygen adsorption on Pu (111) surface

Huda

Ray

2005

Int J of Quantum Chemistry

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“…As a matter of fact, no ordered moments have been observed for both ␣ Pu and ␦-stabilized Pu with magnetic-susceptibility measurements, 22 SR, 23 and nuclear magnetic resonance. 24,25 Already in 1975, Johansson and Rosengren 12 suggested a 5f 5 like ground state, however, this solution converges to a magnetically ordered state. A convenient way to accommodate the absence of magnetic ordering in Pu metal was proposed in several recent publications ͑Refs.…”

Section: Introductionmentioning

confidence: 94%

Valence fluctuations in thin films and theαandδphases of Pu metal determined by4fcore-level photoemission calculations

Laan

Taguchi

2010

Phys. Rev. B

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The average number of 5f electrons making up the valence state in plutonium metal together with the electronic fluctuations on each metal site has been a recent subject of debate. For the ␦ phase of Pu, where compared to the ␣ phase increased localization ͑more atomiclike character͒ leads to decreased overlap and volume increase, an f count close to either 5 or 6 has been proposed depending on the type of electronic structure calculation. In order to resolve the controversy, we analyze the Pu 4f photoemission spectrum, which displays well screened and poorly screened peaks that can be used as a measure for the degree of localization. A simple analytical two-level model already shows on general grounds that the f count for Pu must be between 5 and 5.5. Furthermore, we present detailed Anderson impurity model calculations including the full multiplet structure for Pu 4f photoemission, which are compared to previous experimental results obtained from 1 to 9 monolayers thin films of Pu on Mg and from Pu metal in the ␣ and ␦ phases. The trend in the satellite to main peak intensity ratio as a function of the Pu layer thickness gives a clear indication that Pu metal has an 5f 5 like ground state. For the Pu allotropes and thicker films an f count of 5.22 is obtained with a Coulomb interaction U = 4 eV. The 5f fluctuations in Pu metal are very prominent and strongly material dependent. The calculations give a ground state with 9.6% f 4 , 58.8% f 5 , and 31.6% f 6 for the ␣ phase and 5.7% f 4 , 66.4% f 5 , and 27.8% f 6 for the ␦ phase while for the thin films the amount of f 5 and the localization strongly increase with reduced thickness. The obtained findings are in agreement with recent electronic structure calculations for ␦ Pu using local-density approximation with dynamical mean-field theory and with the branching-ratio analysis of the Pu N 4,5 edge in electron-energy-loss spectroscopy.

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“…The hybridization between the 5f electrons of Pu and the conduction electrons is therefore much weaker than has gen-erally been assumed; hence, the 5f electrons are close to the threshold for localization and Pu is arguably the most strongly correlated of the elements. The experimental signatures of the pseudogapped state are reminiscent of those in transition-metal oxides [29][30][31][32][33], and include a peak in the electronic heat capacity below T * , accompanied by a thermally activated Hall coefficient [34] and a downturn below T * in physical quantities that are sensitive to the thermally averaged electronic density of states such as the electrical resistivity, Knight shift and magnetic susceptibility [35][36][37][38][39][40].…”

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confidence: 99%