Specific heat of the β-pyrochlore oxide superconductors CsOs 2O6 and RbOs2O6

Zenji Hiroi; Shigeki Yonezawa; Takaki Muramatsu; Jun Ichi Yamaura; Yuji Muraoka

doi:10.1143/JPSJ.74.1255

Specific heat of the β-pyrochlore oxide superconductors CsOs ₂O₆ and RbOs₂O₆

Zenji Hiroi, Shigeki Yonezawa, Takaki Muramatsu, Jun Ichi Yamaura, Yuji Muraoka

Research output: Contribution to journal › Article › peer-review

51 Citations (Scopus)

Abstract

Two β-pyrochlore oxide superconductors, CsOs₂O₆ and RbOs₂O₆, are studied thermodynamically by measuring specific heat on polycrystalline samples. It is found that a Sommerfeld coefficient γ is nearly equal, 20 mJ/K² mol Os, in the two oxides with different superconducting transition temperatures; T_c = 3.3 and 6.3 K, respectively. This suggests that the density of states at the Fermi level is not a crucial parameter to determine the T_c of the β-pyrochlore oxide superconductors, which is incompatible with the general expectation for a conventional BCS-type superconductor. Anomalous lattice contributions to specific heat at low temperature are also reported, which may come from nearly localized phonon modes associated with the rattling of the alkali metal ions weakly bound in an oversized cage formed by OsO₆ octahedra.

Original language	English
Pages (from-to)	1255-1262
Number of pages	8
Journal	journal of the physical society of japan
Volume	74
Issue number	4
DOIs	https://doi.org/10.1143/JPSJ.74.1255
Publication status	Published - Apr 1 2005
Externally published	Yes

Keywords

CsOsO
Rattling phonon
RbOsO
Sommerfeld coefficient
Specific heat
Superconductivity
β-pyrochlore oxide

ASJC Scopus subject areas

Physics and Astronomy(all)

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@article{533760f5065e4d95b639281ac7a7d92e,

title = "Specific heat of the β-pyrochlore oxide superconductors CsOs 2O6 and RbOs2O6",

abstract = "Two β-pyrochlore oxide superconductors, CsOs2O6 and RbOs2O6, are studied thermodynamically by measuring specific heat on polycrystalline samples. It is found that a Sommerfeld coefficient γ is nearly equal, 20 mJ/K2 mol Os, in the two oxides with different superconducting transition temperatures; Tc = 3.3 and 6.3 K, respectively. This suggests that the density of states at the Fermi level is not a crucial parameter to determine the Tc of the β-pyrochlore oxide superconductors, which is incompatible with the general expectation for a conventional BCS-type superconductor. Anomalous lattice contributions to specific heat at low temperature are also reported, which may come from nearly localized phonon modes associated with the rattling of the alkali metal ions weakly bound in an oversized cage formed by OsO6 octahedra.",

keywords = "CsOsO, Rattling phonon, RbOsO, Sommerfeld coefficient, Specific heat, Superconductivity, β-pyrochlore oxide",

author = "Zenji Hiroi and Shigeki Yonezawa and Takaki Muramatsu and Yamaura, {Jun Ichi} and Yuji Muraoka",

year = "2005",

month = apr,

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doi = "10.1143/JPSJ.74.1255",

language = "English",

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TY - JOUR

T1 - Specific heat of the β-pyrochlore oxide superconductors CsOs 2O6 and RbOs2O6

AU - Hiroi, Zenji

AU - Yonezawa, Shigeki

AU - Muramatsu, Takaki

AU - Yamaura, Jun Ichi

AU - Muraoka, Yuji

PY - 2005/4/1

Y1 - 2005/4/1

N2 - Two β-pyrochlore oxide superconductors, CsOs2O6 and RbOs2O6, are studied thermodynamically by measuring specific heat on polycrystalline samples. It is found that a Sommerfeld coefficient γ is nearly equal, 20 mJ/K2 mol Os, in the two oxides with different superconducting transition temperatures; Tc = 3.3 and 6.3 K, respectively. This suggests that the density of states at the Fermi level is not a crucial parameter to determine the Tc of the β-pyrochlore oxide superconductors, which is incompatible with the general expectation for a conventional BCS-type superconductor. Anomalous lattice contributions to specific heat at low temperature are also reported, which may come from nearly localized phonon modes associated with the rattling of the alkali metal ions weakly bound in an oversized cage formed by OsO6 octahedra.

AB - Two β-pyrochlore oxide superconductors, CsOs2O6 and RbOs2O6, are studied thermodynamically by measuring specific heat on polycrystalline samples. It is found that a Sommerfeld coefficient γ is nearly equal, 20 mJ/K2 mol Os, in the two oxides with different superconducting transition temperatures; Tc = 3.3 and 6.3 K, respectively. This suggests that the density of states at the Fermi level is not a crucial parameter to determine the Tc of the β-pyrochlore oxide superconductors, which is incompatible with the general expectation for a conventional BCS-type superconductor. Anomalous lattice contributions to specific heat at low temperature are also reported, which may come from nearly localized phonon modes associated with the rattling of the alkali metal ions weakly bound in an oversized cage formed by OsO6 octahedra.

KW - CsOsO

KW - Rattling phonon

KW - RbOsO

KW - Sommerfeld coefficient

KW - Specific heat

KW - Superconductivity

KW - β-pyrochlore oxide

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