Thermal Conductivity of the Pyrochlore Superconductor KOs2O6: Strong Electron Correlations and Fully Gapped Superconductivity

Abstract

To elucidate the nature of the superconducting ground state of the geometrically frustrated pyrochlore KOs2O6 (Tc=9.6K), the thermal conductivity was measured down to low temperatures (~Tc/100). We found that the quasiparticle mean free path is strikingly enhanced below a transition at Tp=7.5K, indicating enormous electron inelastic scattering in the normal state. In a magnetic field the conduction at T ->0K is nearly constant up to ~0.4Hc2, in contrast with the rapid growth expected for superconductors with an anisotropic gap. This unambiguously indicates a fully gapped superconductivity, in contrast to the previous studies. These results highlight that KOs2O6 is unique among superconductors with strong electron correlations.

5 pages, 4 figures, accepted for publication in Phys. Rev. Lett

References in corpus (2)

• The ground state of heavily-overdoped non-superconducting La${}_{2-x}$Sr${}_x$CuO${}_4$
• Mass enhancement, correlations, and strong coupling superconductivity in the beta-pyrochlore KOs2O6

Cited by in corpus (18)

• Exotic Superconducting Properties in the Electron-Hole Compensated Heavy Fermion `Semimetal' URu2Si2
• Nodal Structure of Unconventional Superconductors Probed by the Angle Resolved Thermal Transport Measurements
• Extremely strong-coupling superconductivity and anomalous lattice properties in the beta-pyrochlore oxide KOs2O6
• Rattling-Induced Superconductiviy in the Beta-Pyrochlore Oxides AOs2O6
• NMR Observation of Rattling Phonons in the Pyrochlore Superconductor KOs2O6
• Uncommonly High Upper Critical Field in the Superconducting KOs${}_2$O${}_6$ Pyrochlore
• Flux Line Lattice Melting and the Formation of a Coherent Quasiparticle Bloch State in the Ultraclean URu${}_2$Si${}_2$ Superconductor
• Neutron Scattering Study of the Localized Mode in the beta-Pyrochlore Superconductors AOs2O6
• Superconducting Transition in the $\beta$-Pyrochlore AOs${}_2$O${}_6$ (A=Cs, Rb, K) under Pressure
• A Possible Phase Transition in beta-pyrochlore Compounds
• Vortex Redistribution below the First-Order Transition Temperature in the β-Pyrochlore Superconductor KOs_2O_6
• Unconventional Superconducting Symmetry in a Checkerboard Antiferromagnet
• Microscopic properties of vortex state in YB6 probed by muon spin rotation
• Supersolid phases of a doped valence-bond quantum antiferromagnet: Evidence for a coexisting superconducting order parameter
• Scanning Tunneling Spectroscopy in the Superconducting State and Vortex Cores of the beta-pyrochlore KOs2O6
• Theoretical study of NMR relaxation due to rattling phonons
• Magnetic and charge transport properties of the Na-based Os oxide pyrochlore
• Quasi-Classical Calculation of the Mixed-State Thermal Conductivity in s-Wave and d-Wave Superconductors