Quasiparticle Excitation in the Superconducting Pyrochlore Cd2Re2O7Probed by Muon Spin Rotation

Kadono, R.; Higemoto, Wataru; Koda, A.; Kawasaki, Yu; Hanawa, Masafumi; Hiroi, Zenji

doi:10.1143/jpsj.71.709

Cited by 24 publications

(14 citation statements)

References 25 publications

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“…However, we have little experimental evidence to imply exotic superconductivity at the moment. To be noted is that Kadono measured the penetration depth using the mSR technique on our polycrystalline and single-crystal samples and found an unconventional temperature dependence suggesting an anisotropic superconducting gap [21]. Further information is necessary to discuss on the mechanism.…”

Section: Discussionmentioning

confidence: 88%

Superconducting properties of the pyrochlore oxide Cd2Re2O7

Hiroi

Hanawa

2002

Journal of Physics and Chemistry of Solids

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We report the superconducting properties of the pyrochlore oxide Cd2Re2O7. The bulk superconducting transition temperature Tc is about 1.0 K, and the upper critical field Hc2 determined by the measurement of specific heat under magnetic fields is 0.29 T. The superconducting coherence length is estimated to be 34 nm. Specific heat data measured on single crystals suggest that the superconducting gap of Cd2Re2O7 is nodeless.Comment: 6 pages, 6 figures, 1 table, to be published in J. Chem. Phys. Solid

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Section: Discussionmentioning

confidence: 88%

Superconducting properties of the pyrochlore oxide Cd2Re2O7

Hiroi

Hanawa

2002

Journal of Physics and Chemistry of Solids

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“…4,5 While the superconductivity turned out to be of a Bardeen-Cooper-Schrieffer type-II, 6,7 the normal state Cd 2 Re 2 O 7 is intriguing in its own right. It features a moderately correlated Fermi-liquid state right above the superconductivity transition at T c ϳ 1.0 K, 2 a weak changeover at TЈ ϳ 120 K that lacks a signature in thermodynamics and is possibly imperfection driven, 8,9 as well as a metal-to-better metal second-order phase transition at T ‫ء‬ = 200 K that is accompanied by a cubic-to-tetragonal structure change.…”

Section: Introductionmentioning

confidence: 99%

Probing lattice dynamics ofCd2Re2O7pyrochlore: Thermal transport and thermodynamics study

Hitchcock

Bredeson

et al. 2010

Phys. Rev. B

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Cd 2 Re 2 O 7 single crystals exhibit an amorphouslike lattice thermal conductivity, latt . At temperatures about twice the Debye temperature, the phonon mean-free path approaches the value of the average Cd-Cd spacing while the specific heat is at values notably lower than the classical Dulong-Petit limit. We show that a model that treats Cd ions as Einstein oscillators embedded in a Debye host with strong optical-acoustic phonon coupling and some very high-frequency optical phonon modes in the system, can account for these features. Despite no structural change, latt undergoes a smooth slope change at ϳ340 K, above which the resistivity adopts a weak power-law behavior. The combined results of resistivity, thermopower, specific-heat, thermalconductivity, and Hall coefficient measurements corroborate that a phonon-mediated electron-hole scattering mechanism sets in above room temperature.

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“…4,5) In contrast, µSR measurements have pointed out a possibility of an anisotropic superconducting order parameter. 6) Besides superconductivity, Cd 2 Re 2 O 7 exhibits an interesting phase transition at high temperature of T s = 200 K, which may reflect the peculiar electronic structure of the compound and must be closely related to the occurrence of superconductivity at low temperature. 1,7,8) It is believed that, as temperature decreases, the crystal structure changes from the ideal cubic pyrochlore structure with space group Fd3m to another slightly distorted cubic structure with space group F43m.…”

Section: §1 Introductionmentioning

confidence: 99%

High-Pressure Study on the Superconducting Pyrochlore Oxide Cd₂Re₂O₇

et al. 2002

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Very recently superconductivity with a critical temperature T c ~ 1 K was found in the pyrochlore oxide Cd 2 Re 2 O 7 . [1][2][3] It is the first superconductor in the family of pyrochlore oxides which possess a unique tetrahedral network of transition metal ions. The following experimental efforts to elucidate the mechanism of the superconductivity are now being done extensively. Specific heat and Re NQR measurements have revealed that the superconducting gap is almost isotropic. 4,5) In contrast, µSR measurements have pointed out a possibility of an anisotropic superconducting order parameter. 6)Besides superconductivity, Cd 2 Re 2 O 7 exhibits an interesting phase transition at high temperature of T s = 200 K, which may reflect the peculiar electronic structure of the compound and must be closely related to the occurrence of superconductivity at low temperature. 1,7,8) It is believed that, as temperature decreases, the crystal structure changes from the ideal cubic pyrochlore structure with space group Fd3m to another slightly distorted cubic structure with space group F43m.7) The transition is of the second order and the cell volume increases gradually with decreasing temperature below T s . The structural refinements of the low-temperature (LT) phase has not yet been completed. However, a consideration on the change of space groups from Fd3m to F43m which involves the lack of inversion symmetry at the Re site leads us to assume that each Re tetrahedron can expand or shrink alternatingly without distortions, resulting in a kind of breathing mode frozen in the three-dimensional network.7) It is considered, in other words, that all the bonds of the Re tetrahedral network are identical forming the diamond structure in the high-temperature (HT) phase, while they exhibit an alternation in the LT phase forming the zinc-blende structure. 9)On the other hand, this structural transition is accompanied by various, dramatic changes in physical properties:1) The resistivity is almost independent of temperature above T s , while it shows a good metallic behavior below T s with an apparent kink at T s . Correspondingly, magnetic susceptibility exhibits a sudden decrease below T s , with the value at T = 5 K reduced by about 35% compared with that at room temperature.1) These facts mean that a crucial change in the electronic structure occurs at the transition, suggesting that the origin is purely electronic and attributable to an inherent instability in the electronic structure of the pyrochlore oxide.Since the cell volume is larger in the LT phase, we have expected that the application of high pressure can suppress the transition and thus can stabilize the HT structure. This is the motivation of the present high-pressure (HP) study. Here we report a structural study and resistivity measurements on Cd 2 Re 2 O 7 under high pressure. An intriguing P-T phase diagram has been obtained, which illustrates a rich physics in the itinerant electron system on the pyrochlore lattice. §2. ExperimentalSingle crystal and polycrystalli...

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Quasiparticle Excitation in the Superconducting Pyrochlore Cd₂Re₂O₇Probed by Muon Spin Rotation

Cited by 24 publications

References 25 publications

Superconducting properties of the pyrochlore oxide Cd2Re2O7

Superconducting properties of the pyrochlore oxide Cd2Re2O7

Probing lattice dynamics ofCd2Re2O7pyrochlore: Thermal transport and thermodynamics study

High-Pressure Study on the Superconducting Pyrochlore Oxide Cd₂Re₂O₇

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Quasiparticle Excitation in the Superconducting Pyrochlore Cd2Re2O7Probed by Muon Spin Rotation

Cited by 24 publications

References 25 publications

Superconducting properties of the pyrochlore oxide Cd2Re2O7

Superconducting properties of the pyrochlore oxide Cd2Re2O7

Probing lattice dynamics ofCd2Re2O7pyrochlore: Thermal transport and thermodynamics study

High-Pressure Study on the Superconducting Pyrochlore Oxide Cd2Re2O7

Contact Info

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Quasiparticle Excitation in the Superconducting Pyrochlore Cd₂Re₂O₇Probed by Muon Spin Rotation

High-Pressure Study on the Superconducting Pyrochlore Oxide Cd₂Re₂O₇