Strongly Correlated Electron Phenomena in the Filled Skutterudites

Maple, M. B.; Baumbach, Ryan; Hamlin, J. J.; Ho, Pei-Chun; Shu, Lei; MacLaughlin, D. E.; Henkie, Z.; Wawryk, R.; Cichorek, T.; Pietraszko, A.

doi:10.1007/978-90-481-2892-1_1

Cited by 6 publications

(10 citation statements)

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“…Although the viability of this interpretation still remains an open issue, the scenario of co-existence between nodal and nodeless pairing gaps finds support in different experimental findings [3,12,14]. In that regard, it is worth mentioning that the same issues persist for PrOs 4 Sb 12 , for which several experimental groups have provided evidence for nodal as well as nodeless superconductivity [2,9,[16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 97%

“…Interestingly, the related compound PrPt 4 Ge 12 has a much higher T c 7.9 K and smaller γ ∼ 60 mJ/(mol·K 2 ), corresponding to a moderate enhancement of the conduction electron effective mass [3]. It is noteworthy that these materials, among many others in the family of filled skutterudites, have been widely studied recently, mainly due to their potential for thermoelectric applications [4,5] as well as a variety of low temperature phenomena such as magnetic and quadrupolar order and metal-insulator transitions [1,[6][7][8][9][10].…”

Section: Introductionmentioning

confidence: 99%

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Multiband superconductivity in the correlated electron filled skutterudite systemPr1−xCexPt4Ge12

et al. 2016

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Studies of superconductivity in multiband correlated electronic systems has become one of the central topics in condensed matter/materials physics. In this paper, we present the results of thermodynamic measurements on the superconducting filled skutterudite system Pr1−xCexPt4Ge12 (0 ≤ x ≤ 0.2) to investigate how substitution of Ce at Pr sites affects superconductivity. We find that an increase in Ce concentration leads to a suppression of the superconducting transition temperature from Tc ∼ 7.9 K for x = 0 to Tc ∼ 0.6 K for x = 0.14. Our analysis of the specific heat data for x ≤ 0.07 reveals that superconductivity must develop in at least two bands: the superconducting order parameter has nodes on one Fermi pocket and remains fully gapped on the other. Both the nodal and nodeless gap values decrease, with the nodal gap being suppressed more strongly, with Ce substitution. Ultimately, the higher Ce concentration samples (x > 0.07) display a nodeless gap only.

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Section: Introductionmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

Multiband superconductivity in the correlated electron filled skutterudite systemPr1−xCexPt4Ge12

et al. 2016

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“…An example is the filled skutterudite family of isostructural lanthanide intermetallics [1], where the unconventional heavy-fermion superconductor PrOs 4 Sb 12 and its alloys have been the subject of considerable interest [2,3]. The isomorph NdOs 4 Sb 12 is a ferromagnet with Curie temperature T C ≃ 0.8 K [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Muon spin rotation and relaxation inPr1−xNdxOs4
MacLaughlin
¹
,
Ho
²
,
Shu
³

et al. 2014
Phys. Rev. B
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Muon spin rotation and relaxation (µSR) experiments have been carried out to characterize magnetic and superconducting ground states in the Pr1−xNdxOs4Sb12 alloy series. In the ferromagnetic end compound NdOs4Sb12 the spontaneous local field at positive-muon (µ + ) sites below the ordering temperature TC is greater than expected from dipolar coupling to ferromagnetically aligned Nd 3+ moments, indicating an additional indirect RKKY-like transferred hyperfine mechanism. For 0.45 ≤ x ≤ 0.75, µ + spin relaxation rates in zero and weak longitudinal applied fields indicate that static fields at µ + sites below TC are reduced and strongly disordered. We argue this is unlikely to be due to reduction of Nd 3+ moments, and speculate that the Nd 3+ -µ + interaction is suppressed and disordered by Pr doping. In an x = 0.25 sample, which is superconducting below Tc = 1.3 K, there is no sign of "spin freezing" (static Nd 3+ magnetism), ordered or disordered, down to 25 mK. Dynamic µ + spin relaxation is strong, indicating significant Nd-moment fluctuations. The µ + diamagnetic frequency shift and spin relaxation in the superconducting vortex-lattice phase decrease slowly below Tc, suggesting pair breaking and/or possible modification of Fermi-liquid renormalization by Nd spin fluctuations. For 0.25 ≤ x ≤ 0.75, the µSR data provide evidence against phase separation; superconductivity and Nd 3+ magnetism coexist on the atomic scale.

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“…[1][2][3][4] Significant attention has been given to their unusual structure, in which the Ln atom (e.g., La, Ce, Pr, etc.) is weakly bonded to the nearest neighbor X atoms that form a 12-neighbor surrounding cage in two of the unit cell sub-cubes (see Fig.…”

Section: Introductionmentioning

confidence: 99%

“…Many of these materials have semiconducting properties, with a moderate electrical conductivity, σ e . 3,7 Moreover, their Seebeck coefficient, S, is sometimes enhanced, owing to the strong hybridization between the conduction electron and f-electron states. [7][8][9][10] Consequently, these materials have good thermoelectric properties, parametrized by a high value of the figure of merit, ZT = T S 2 σe κtot .…”

Section: Introductionmentioning

confidence: 99%

Complex vibrations in arsenide skutterudites and oxyskutterudites

et al. 2015

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The local structure of two skutterudite families -CeM4As12 (M = Fe, Ru, Os) and LnCu3Ru4O12 (Ln = La, Pr, and Nd) -have been studied using the Extended X-Ray Absorption Fine Structure (EXAFS) technique with a focus on the lattice vibrations about the rare earth "rattler atoms", and the extent to which these vibrations can be considered local modes, with the rattler vibrating inside a nearly rigid cage. X-ray absorption data at all the metal edges were collected over a temperature range of 4 to 300 K and analyzed using standard procedures. The pair-distances from EXAFS results agree quite well with the average structure obtained from diffraction. The cage structure is formed by the M and As atoms in CeM4As12 and by Cu, O, and Ru atoms in LnCu3Ru4O12. Although some of the bonds within the cage are quite stiff (Correlated Debye temperatures, θcD, are ∼ 500 K for CeM4As12 and above 800 K for LnCu3Ru4O12) we show the structure is not completely rigid. For the rattler atom the nearest neighbor pairs have a relatively low Einstein temperature, θE; ∼ 100-120 K for Ce-As and ∼ 130 K for Ln-O. Surprisingly, the behavior of the second neighbor pairs are quite different; for CeM4As12 the second neighbor pairs (Ce-M have a weaker bond while for LnCu3Ru4O12 the Ln-Ru second neighbor pair has a stiffer effective spring constant than the first neighbor pair. In addition, we show that the As4 or CuO4 rings are relatively rigid units and that their vibrations are anisotropic within these cubic structures, with stiff restoring forces perpendicular to the rings and much weaker restoring forces in directions parallel to the rings. Consequently vibrations of the rings may also act as "rattlers" and help suppress thermal conductivity. In general neither the rigid cage approximation nor the simple reduced mass approximation are sufficient for describing rattler behavior.

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Strongly Correlated Electron Phenomena in the Filled Skutterudites

Cited by 6 publications

References 68 publications

Multiband superconductivity in the correlated electron filled skutterudite systemPr1−xCexPt4Ge12

Multiband superconductivity in the correlated electron filled skutterudite systemPr1−xCexPt4Ge12

Muon spin rotation and relaxation inPr1−xNdxOs4
MacLaughlin
¹
,
Ho
²
,
Shu
³

et al. 2014
Phys. Rev. B
Self Cite

Complex vibrations in arsenide skutterudites and oxyskutterudites

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Strongly Correlated Electron Phenomena in the Filled Skutterudites

Cited by 6 publications

References 68 publications

Multiband superconductivity in the correlated electron filled skutterudite systemPr1−xCexPt4Ge12

Multiband superconductivity in the correlated electron filled skutterudite systemPr1−xCexPt4Ge12

Muon spin rotation and relaxation inPr1−xNdxOs4MacLaughlin1, Ho2, Shu3 et al. 2014Phys. Rev. BSelf Cite

Complex vibrations in arsenide skutterudites and oxyskutterudites

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Resources

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Muon spin rotation and relaxation inPr1−xNdxOs4
MacLaughlin
¹
,
Ho
²
,
Shu
³

et al. 2014
Phys. Rev. B
Self Cite