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Test of the Wiedemann-Franz law in an optimally-doped cuprate

Romain Bel·Kamran Behnia·Cyril Proust·Peter van der Linden·Duncan Maude·Sergey I. Vedeneev
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Abstract

We present a study of heat and charge transport in Bi$_{2+x}$Sr$_{2-x}$CuO$_{6+δ}$ focused on the size of the low-temperature linear term of the thermal conductivity at optimal doping level. In the superconducting state, the magnitude of this term implies a d-wave gap with an amplitude close to what has been reported. In the normal state, recovered by the application of a magnetic field, measurement of this term and residual resistivity yields a Lorenz number $L = κ_{N}ρ_{0}/T = 1.3 \pm 0.2 L_{0}$. The departure from the value expected by the Wiedemann-Franz law is thus slightly larger than our estimated experimental resolution.

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Romain Bel, Kamran Behnia, Cyril Proust, Peter van der Linden, Duncan Maude, Sergey I. Vedeneev. 2004-05-05. Test of the Wiedemann-Franz law in an optimally-doped cuprate. https://doi.org/10.1103/physrevlett.92.177003

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