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.
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 | |
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)