Shigeki Yonezawa

New Pyrochlore Oxide Superconductor RbOs2O6

We report the discovery of a new pyrochlore oxide superconductor RbOs 2 O 6 . The compound crystallizes in the same β-pyrochlore structure as the recently discovered superconductor KOs 2 O 6 , where Os atoms form a corner-sharing tetrahedral network called the pyrochlore lattice with Rb or K atoms in the cage. Resistivity, magnetic susceptibility and specific heat measurements on polycrystalline samples evidence a bulk superconductivity with T c =6.3 K.

Extremely strong-coupling superconductivity and anomalous lattice properties in the beta-pyrochlore oxide KOs2O6

Superconducting and normal-state properties of the

New β-Pyrochlore Oxide Superconductor CsOs2O6

\ensuremath{\beta}

Superconductivity in a pyrochlore-related oxide KOs2O6

-pyrochlore oxide

Crystal structure of the pyrochlore oxide superconductor KOs2O6

\mathrm{K}{\mathrm{Os}}_{2}{\mathrm{O}}_{6}

Second Anomaly in the Specific Heat of β-Pyrochlore Oxide Superconductor KOs2O6

are studied by means of thermodynamic and transport measurements. It is shown that the superconductivity is of conventional

NMR observation of rattling phonons in the pyrochlore superconductor KOs2O6.

s

Thermal conductivity of the pyrochlore superconductor KOs2O6: strong electron correlations and fully gapped superconductivity.

-wave type and lies in the extremely strong-coupling regime. Specific heat and resistivity measurements reveal that there are characteristic low-energy phonons that give rise to unusual scattering of carriers due to strong electron-phonon interactions. The entity of the low-energy phonons is ascribed to the heavy rattling of the K ion confined in an oversized cage made of

Specific Heat of the β-Pyrochlore Oxide Superconductors CsOs2O6 and RbOs2O6

\mathrm{Os}{\mathrm{O}}_{6}

Unprecedented Superconductivity in β-Pyrochlore Osmate KOs2O6

octahedra. It is suggested that this electron-rattler coupling mediates the Cooper pairing, resulting in the extremely strong-coupling superconductivity.