Kondo insulating behaviour in the filled skutterudite compound CeOs<sub>4</sub>Sb<sub>12</sub>

Bauer, E.; Ślebarski, A.; Freeman, E. J.; Sirvent, C.; Maple, M. B.

doi:10.1088/0953-8984/13/20/310

Cited by 149 publications

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“…The ferromagnetic transitions are clearly visible as peaks at ∼3 and 8 K for EuRu 4 Sb 12 and EuOs 4 Sb 12 , respectively, and the Curie temperatures, determined from the mid-point of . These values of γ should be considered as an upper limit given the limited fit range and the use of a high temperature extrapolation and are probably more similar to those of LaRu 4 Sb 12 and LaOs 4 Sb 12 [3,18]. It is interesting to note that the γ value of LaFe 4 Sb 12 (γ ∼ 185 mJ mol −1 K −2 [10] and this work) is larger than those for the homologous LaRu 4 Sb 12 and LaOs 4 Sb 12 compounds that have γ = 39, and 36 mJ mol −1 K −2 , respectively [3,18].…”

Section: Specific Heatmentioning

confidence: 84%

“…These values of γ should be considered as an upper limit given the limited fit range and the use of a high temperature extrapolation and are probably more similar to those of LaRu 4 Sb 12 and LaOs 4 Sb 12 [3,18]. It is interesting to note that the γ value of LaFe 4 Sb 12 (γ ∼ 185 mJ mol −1 K −2 [10] and this work) is larger than those for the homologous LaRu 4 Sb 12 and LaOs 4 Sb 12 compounds that have γ = 39, and 36 mJ mol −1 K −2 , respectively [3,18]. Large values of the Sommerfeld coefficient γ ∼ 100 mJ mol −1 K −2 are also observed in the Fe-containing skutterudites NaFe 4 Sb 12 and BaFe 4 Sb 12 , raising the possibility of significant hybridization of the Fe d states with the conduction electrons [19].…”

Section: Specific Heatmentioning

confidence: 84%

“…A host of phenomena are observed in these compounds such as superconductivity, magnetism, heavy fermion, intermediate valence, non-Fermi liquid, and small band gap semiconducting behaviour [3]. The filled skutterudite compounds crystallize in the BCC LaFe 4 P 12 -type structure [4,5] which is derived from the 5 Present address: Los Alamos National Laboratory, Los Alamos, NM 87545, USA.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of ferromagnetic filled skutterudite compounds EuT₄Sb₁₂(T = Fe, Ru, Os)

Bauer

Ślebarski

Frederick

et al. 2004

J. Phys.: Condens. Matter

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The physical properties of single crystals of filled skutterudite compounds EuT 4 Sb 12 (T = Fe, Ru, Os) have been investigated by means of x-ray diffraction, electrical resistivity, specific heat, magnetization, and x-ray absorption spectroscopy measurements. The Eu-based materials crystallize in the LaFe 4 P 12 -type structure (space group I m3 appears to exhibit either canted ferromagnetic or ferrimagnetic order at T C = 88 K whereas EuRu 4 Sb 12 and EuOs 4 Sb 12 are ferromagnets with Curie temperatures of T C = 4 and 9 K, respectively. X-ray absorption near edge spectroscopy measurements reveal a nearly divalent Eu electronic configuration for EuT 4 Sb 12 (T = Fe, Ru, Os) with no significant change with T atom or temperature.

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Section: Specific Heatmentioning

confidence: 84%

Section: Specific Heatmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Investigation of ferromagnetic filled skutterudite compounds EuT₄Sb₁₂(T = Fe, Ru, Os)

Bauer

Ślebarski

Frederick

et al. 2004

J. Phys.: Condens. Matter

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“…We present results on single crystals of PrOs 4 Sb 12 grown by the Sb flux method 18,19 . These samples are aggregates of small single crystals with well developed cubic faces.…”

Section: Methodsmentioning

confidence: 99%

Superconducting phase diagram of the filled skuterruditePrOs4Sb12

et al. 2004

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We present new measurements of the specific heat of the heavy fermion superconductor PrOs4Sb12, on a sample which exhibits two sharp distinct anomalies at Tc1 = 1.89K and Tc2 = 1.72K. They are used to draw a precise magnetic field-temperature superconducting phase diagram of PrOs4Sb12 down to 350 mK. We discuss the superconducting phase diagram of PrOs4Sb12 and its possible relation with an unconventional superconducting order parameter. We give a detailed analysis of Hc2(T ), which shows paramagnetic limitation (a support for even parity pairing) and multiband effects.

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“…The high quality single crystals of PrOs 4 Sb 12 grown from Sb flux [7], have very narrow superconducting transitions in both resistivity and susceptibility and a low residual resistivity ρ 0 < 5µΩcm. The samples naturally crystallized in a cubic shape, where the principal crystallographic axis were confirmed to coincide with faces of the cubes by means of Laue x-ray diffraction.…”

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confidence: 99%

Low-Temperature Specific Heat of the Heavy-Fermion SuperconductorPrOs4Sb12

et al. 2003

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We report the magnetic field dependence of the low temperature specific heat of single crystals of the first Pr-based heavy fermion superconductor PrOs4Sb12. The low temperature specific heat and the magnetic phase diagram inferred from specific heat, resistivity and magnetisation provide compelling evidence of a doublet ground state and hence superconductivity mediated by quadrupolar fluctuations. This establishes PrOs4Sb12 as a very strong contender of superconductive pairing that is neither electron-phonon nor magnetically mediated.PACS numbers: 74.70. Tx, 7127,+a, 75.30.Mb Superconductivity mediated by a pairing potential other than a conventional electron-phonon interaction has been the subject of a very large number of theoretical and experimental investigations over the decades. In recent years, finally, intermetallic compounds have been discovered which, together with the high-T c cuprates, represent prime candidates for magnetically mediated pairing. Surprisingly, however, magnetically mediated pairing thus far has been considered the only serious alternative to electron-phonon mediated pairing, while excitonic and polaronic mechanisms have also been proposed.We have recently reported the discovery of the first Pr-based heavy fermion superconductor PrOs 4 Sb 12 [1], for which the nonmagnetic ground state appeared best described as a crystalline electric field (CEF) doublet. This in turn suggested that the heavy electron liquid is of quadrupolar origin and that consequently quadrupolar fluctuations mediate the superconductive pairing. PrOs 4 Sb 12 hence is a candidate for being the first material in which neither electron-phonon nor magnetic interactions mediate the pairing. However, a magnetic origin could not be completely ruled out [1] and recent low temperature specific heat measurements are reported to be consistent with a singlet CEF ground state hence questioning the hypothesis of quadrupolar pairing [2].In order to settle the question of the ground state and thus the possibility of the first example of quadrupolar mediated superconductive pairing demands definitive establishement of (i) the CEF level scheme, (ii) the unconventional nature of the superconductivity, and (iii) coupling of the CEF excitations to the conduction electrons. Here we report specific heat measurements of high quality single crystals of PrOs 4 Sb 12 at low T and high magnetic field. We show that the zero field data of the single crystals and the magnetic phase diagram as established from the specific heat, resistivity and magnetisation, as well as the observation of a novel high field ground state, provide compelling evidence of a nonmagnetic doublet CEF ground state intimately linked to the conduction electrons. This unambiguously establishes quadrupolar fluctuations as the most likely pairing mechanism. Moreover, we observe two superconducting transitions giving evidence of two distinct superconducting phases.Previous experiments on pressed pellets of tiny single crystals of PrOs 4 Sb 12 [1] revealed superconductivity ...

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Kondo insulating behaviour in the filled skutterudite compound CeOs₄Sb₁₂

Cited by 149 publications

References 34 publications

Investigation of ferromagnetic filled skutterudite compounds EuT₄Sb₁₂(T = Fe, Ru, Os)

Investigation of ferromagnetic filled skutterudite compounds EuT₄Sb₁₂(T = Fe, Ru, Os)

Superconducting phase diagram of the filled skuterruditePrOs4Sb12

Low-Temperature Specific Heat of the Heavy-Fermion SuperconductorPrOs4Sb12

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Kondo insulating behaviour in the filled skutterudite compound CeOs4Sb12

Cited by 149 publications

References 34 publications

Investigation of ferromagnetic filled skutterudite compounds EuT4Sb12(T = Fe, Ru, Os)

Investigation of ferromagnetic filled skutterudite compounds EuT4Sb12(T = Fe, Ru, Os)

Superconducting phase diagram of the filled skuterruditePrOs4Sb12

Low-Temperature Specific Heat of the Heavy-Fermion SuperconductorPr﻿Os4Sb12

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Kondo insulating behaviour in the filled skutterudite compound CeOs₄Sb₁₂

Investigation of ferromagnetic filled skutterudite compounds EuT₄Sb₁₂(T = Fe, Ru, Os)

Investigation of ferromagnetic filled skutterudite compounds EuT₄Sb₁₂(T = Fe, Ru, Os)

Low-Temperature Specific Heat of the Heavy-Fermion SuperconductorPrOs4Sb12