Unprecedented superconductivity in β-pyrochlore osmate KOs 2O6

Zenji Hiroi, Shigeki Yonezawa, Yuji Muraoka

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48 Citations (Scopus)


Superconductivity in the potassium osmium oxide KOs2O 6 crystallizing in the β-pyrochlore structure is studied by electrical resistivity, magnetic susceptibility and specific heat measurements. It is the second superconductor in the family of pyrochlore oxides, following the α-type pyrochlore oxide Cd2Re2O7 which is believed to be a conventional s-wave superconductor. The superconducting transition temperature Tc of KOs2O 6 is 9.6 K, almost one order higher than the Tc -1.0 K of Cd2Re2O7. Moreover, the superconductivity of KOs2O6 is markedly robust under high magnetic fields, with a large upper critical magnetic field Hc2 of about 38 T, which seems to exceed Pauli's limit expected for conventional superconductivity. This is also in contrast to the case of Cd2Re2O7, in which the HC2 is 0.29 T, much smaller than the corresponding Pauli's limit. These distinct contrasts strongly suggest that the mechanism of superconductivity is essentially different between the two pyrochlore oxides.

Original languageEnglish
Pages (from-to)1651-1654
Number of pages4
Journaljournal of the physical society of japan
Issue number7
Publication statusPublished - Jul 1 2004
Externally publishedYes


  • Electrical resistivity
  • Frustration
  • KOsO
  • Magnetic susceptibility
  • Pyrochlore oxide
  • Specific heat
  • Superconductivity

ASJC Scopus subject areas

  • General Physics and Astronomy


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