α-uranium phase in compressed neodymium metal

Chesnut, Gary N.; Vohra, Yogesh K.

doi:10.1103/physrevb.61.r3768

Cited by 35 publications

(34 citation statements)

References 17 publications

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“…The behavior of volume collapse transitions in rare earth metals has been interpreted in terms of either a Mott metallization of the f -states (Hubbard model) or Kondo screening of the f magnetic moment (periodic Anderson model), although it now appears that the two models may be closely related. 24 Similar low symmetry structures appear in Nd 25 and Sm 26,27 metals at high pressure without any significant volume collapse. Studies of the these transitions in pure rare earth elements continue to be of fundamental interest since many materials which exhibit heavy fermion, quantum critical, non-Fermi liquid, and/or unconventional superconducting behaviors are based on rare earth ions with unstable valences.…”

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confidence: 62%

Low-temperature electrical resistivity of praseodymium at pressures up to 120 GPa

et al. 2011

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confidence: 62%

Low-temperature electrical resistivity of praseodymium at pressures up to 120 GPa

et al. 2011

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“…In contrast to these apparently general trends, it has been recently shown that Nd reaches the characteristic itinerant α-U structure in a relatively continuous fashion without any phase transitions of unusually large volume change, 13 while in an analogous actinide system, Am is noted to undergo two collapse transitions.…”

Section: Introductionmentioning

confidence: 86%

Combined local-density and dynamical mean field theory calculations for the compressed lanthanides Ce, Pr, and Nd

McMahan

2005

Phys. Rev. B

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This paper reports calculations for compressed Ce (4f 1 ), Pr (4f 2 ), and Nd (4f 3 ) using a combination of the local-density approximation (LDA) and dynamical mean field theory (DMFT), or LDA+DMFT. The 4f moment, spectra, and the total energy among other properties are examined as functions of volume and atomic number for an assumed face-centered cubic (fcc) structure. These materials are seen to be strongly localized at ambient pressure and for compressions up through the experimentally observed fcc phases (γ phase for Ce), in the sense of having fully formed Hund's rules moments and little 4f spectral weight at the Fermi level. Subsequent compression for all three lanthanides brings about significant deviation of the moments from their Hund's rules values, a growing Kondo resonance at the Fermi level, an associated softening in the total energy, and quenching of the spin orbit since the Kondo resonance is of mixed spin-orbit character while the lower Hubbard band is predominantly j = 5/2. While the most dramatic changes for Ce occur within the two-phase region of the γ-α volume collapse transition, as found in earlier work, those for Pr and Nd occur within the volume range of the experimentally observed distorted fcc (dfcc) phase, which is therefore seen here as transitional and not part of the localized trivalent lanthanide sequence. The experimentally observed collapse to the α-U structure in Pr occurs only on further compression, and no such collapse is found in Nd. These lanthanides start closer to the localized limit for increasing atomic number, and so the theoretical signatures noted above are also offset to smaller volume as well, which is possibly related to the measured systematics of the size of the volume collapse being 15%, 9%, and none for Ce, Pr, and Nd, respectively.

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“…6 for Ce, 8,9,10 Pr, 12,13,14,15 and Nd. 5,6 At large volume only the face centered cubic (fcc) phase is labelled, which is the end of the localized, trivalent rare earth series, 1 with all three rare earths found in the preceeding, doublehexagonal close packed phase at ambient conditions. The two most dramatic theoretical diagnostics are shown for comparison, J s (J s +1) and w n−1 , and while they were calculated everywhere assuming an fcc structure, it is hoped nonetheless that their volume dependence is sufficiently insensitive to structure so as to still provide useful insights.…”

Section: Resultsmentioning

confidence: 99%

Screening of4fmoments and delocalization in the compressed light rare earths

2009

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Spin and charge susceptibilities and the 4f n , 4f n−1 , and 4f n+1 configuration weights are calculated for compressed Ce (n = 1), Pr (n = 2), and Nd (n = 3) metals using dynamical mean field theory combined with the local-density approximation. At ambient and larger volumes these trivalent rare earths are pinned at sharp 4f n configurations, their 4f moments assume atomic-limiting values, are unscreened, and the 4f charge fluctuations are small indicating little f state density near the Fermi level. Under compresssion there is dramatic screening of the moments and an associated increase in both the 4f charge fluctuations and static charge susceptibility. These changes are coincident with growing weights of the 4f n−1 configurations, which it is argued are better measures of delocalization than the 4f n+1 weights which are compromised by an increase in the number of 4f electrons caused by rising 6s, 6p bands. This process is continuous and prolonged as a function of volume, with strikingly similarity among the three rare earths, aside from the effects moderating and shifting to smaller volumes for the heavier members. The observed α-γ collapse in Ce occurs over the large-volume half of this evolution, the Pr analog at smaller volumes, and Nd has no collapse.

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α-uranium phase in compressed neodymium metal

Cited by 35 publications

References 17 publications

Low-temperature electrical resistivity of praseodymium at pressures up to 120 GPa

Low-temperature electrical resistivity of praseodymium at pressures up to 120 GPa

Combined local-density and dynamical mean field theory calculations for the compressed lanthanides Ce, Pr, and Nd

Screening of4fmoments and delocalization in the compressed light rare earths

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