Thermoelectric studies of KxFe2-ySe2: weakly correlated superconductor

Abstract

We report thermal transport measurement of KxFe2-ySe2 superconducting single crystal. Significant peak anomaly in thermal conductivity is observed at nearly TC/2 indicating a large phonon mean-free-path in the superconducting state. The zero-temperature extrapolated thermoelectric power is smaller than the value in typical strongly correlated superconductors, implying large normalized Fermi temperature. In contrast to other iron superconductors, thermoelectric power in our sample does not exhibit significant anomalies. These findings indicate that KxFe2-ySe2 is a weakly or intermediately correlated superconductor without significant Fermi surface nesting.

Revised version, 5 pages, 5 figures, Will appear in Physical Review B

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• Anisotropic magnetism, superconductivity, and the phase diagram of Rb(1-x)Fe(2-y)Se2
• Ca${}_3$Ir${}_4$Sn${}_{13}$: A weakly correlated nodeless superconductor
• Thermoelectric properties of iron-based superconductors and parent compounds
• Evolution of correlation strength in KxFe(2-y)Se2 superconductor doped with S
• Magnetism of the Fe${}^{2+}$ and Ce${}^{3+}$ sublattices in Ce${}_2$O${}_2$FeSe${}_2$: a combined neutron powder diffraction, inelastic neutron scattering and density functional study
• Study of the magnetic state of K${}_{0.8}$Fe${}_{1.6}$Se${}_2$ using the five-orbital Hubbard model in the Hartree-Fock approximation
• High-pressure study of superconducting and non-superconducting single crystals of the same nominal composition Rb0.8Fe2Se2
• Insulating and metallic spin glass in K${}_x$Fe${}_{2-\delta -y}$Ni${}_y$Se${}_2$ (0.06 $\le$ $y$ $\le$ 1.44) single crystals
• Effective tight-binding model for the iron vacancy ordered A${}_y$FeSe${}_2$
• Thermoelectricity and electronic correlations enhancement in FeS by slight Se substitution
• Synthesis and physical properties of the new potassium iron selenide superconductor K0.80Fe1.76Se2