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arXiv · 1503.07572

Wiedemann-Franz law in the underdoped cuprate superconductor YBa2Cu3Oy

G. Grissonnanche·F. Laliberte·S. Dufour-Beausejour·M. Matusiak·S. Badoux·F. F. Tafti·B. Michon·A. Riopel·O. Cyr-Choiniere·J. C. Baglo·B. J. Ramshaw·R. Liang·D. A. Bonn·W. N. Hardy·S. Kramer·D. LeBoeuf·D. Graf·N. Doiron-Leyraud·L. Taillefer
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Abstract

The recent detection of charge-density modulations in YBa2Cu3Oy and other cuprate superconductors raises new questions about the normal state of underdoped cuprates. In one class of theories, the modulations are intertwined with pairing in a dual state, expected to persist up to high magnetic fields as a vortex liquid. In support of such a state, specific heat and magnetisation data on YBa2Cu3Oy have been interpreted in terms of a vortex liquid persisting above the vortex-melting field Hvs at T = 0. Here we report high-field measurements of the electrical and thermal Hall conductivities in YBa2Cu3O6.54 that allow us to probe the Wiedemann-Franz law, a sensitive test of the presence of superconductivity in a metal. In the T = 0 limit, we find that the law is satisfied for fields immediately above Hvs. This rules out the existence of a vortex liquid and it places strict constraints on the nature of the normal state in underdoped cuprates.

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G. Grissonnanche, F. Laliberte, S. Dufour-Beausejour, M. Matusiak, S. Badoux, F. F. Tafti, B. Michon, A. Riopel, O. Cyr-Choiniere, J. C. Baglo, B. J. Ramshaw, R. Liang, D. A. Bonn, W. N. Hardy, S. Kramer, D. LeBoeuf, D. Graf, N. Doiron-Leyraud, L. Taillefer. 2015-03-25. Wiedemann-Franz law in the underdoped cuprate superconductor YBa2Cu3Oy. https://doi.org/10.1103/physrevb.93.064513

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