Wiedemann-Franz law in the underdoped cuprate superconductor YBa 2 Cu 3 O y

G. Grissonnanche (1) , F. Laliberté (1) , S. Dufour-Beauséjour (1) , M. Matusiak (2, 1) , Sven Badoux (1) , F. Tafti (1) , B. Michon (1) , A. Riopel (1) , O. Cyr-Choinière (1) , J. Baglo (3) , B. Ramshaw (3) , R. Liang (3, 4) , A. Bonn , W. Hardy (3) , S. Kramer (5) , D. Leboeuf (6, 5) , D. Graf , N. Doiron-Leyraud , Louis Taillefer (1)

1 Département de Physique et RQMP
2 Institute of Low Temperature and Structure Research [Polish Academy of Sciences]
3 University of British Columbia [Vancouver]
4 CIFAR - Canadian Institute for Advanced Research
5 LNCMI-G - Laboratoire national des champs magnétiques intenses - Grenoble
6 DAPNIA - Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée

The electrical and thermal Hall conductivities of the cuprate superconductor YBa2Cu3Oy, σxy and κxy, were measured in a magnetic field up to 35 T, at a hole concentration (doping) p=0.11. In the T=0 limit, we find that the Wiedemann-Franz law, κxy/T=(π2/3)(kB/e)2σxy, is satisfied for fields immediately above the vortex-melting field Hvs. This rules out the existence of a vortex liquid at T=0 and it puts a clear constraint on the nature of the normal state in underdoped cuprates, in a region of the doping phase diagram where charge-density-wave order is known to exist. As the temperature is raised, the Lorenz ratio, Lxy=κxy/(σxyT), decreases rapidly, indicating that strong small-q scattering processes are involved.

Domaines: Supraconductivité [cond-mat.supr-con]; Electrons fortement corrélés [cond-mat.str-el]

G. Grissonnanche, F. Laliberté, S. Dufour-Beauséjour, M. Matusiak, Sven Badoux, et al.. Wiedemann-Franz law in the underdoped cuprate superconductor YBa 2 Cu 3 O y. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2016, 93 (6), pp.064513. ⟨10.1103/PhysRevB.93.064513⟩. ⟨hal-02008807⟩