2015/03/31 by G. Grissonnanche, F. Laliberte, S. Dufour-Beausejour +16 · 1 citation
Physics and Astronomy · #cond-mat.supr-con
paper · pdf · doi:10.1103/physrevb.93.064513
published as Phys. Rev. B 93, 064513 (2016) · 8 pages, includes main text and supplementary information
arxiv created 2016/02/24 · arxiv updated 2016/02/25
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.