Thermal conductivity across the phase diagram of cuprates: low-energy quasiparticles and doping dependence of the superconducting gap

M. Sutherland , D.G. Hawthorn , R.W. Hill , F. Roning , S. Wakimoto , H. Zhang , Cyril Proust (1) , E. Boaknin , C. Lupien , L. Taillefer , R. Liang , D.A. Bonn , W.N. Hardy , R. Gagnon , N.E. Hussey , T. Kimura , M. Nohara , H. Takagi

1 LNCMP - Laboratoire National des Champs Magnétiques Pulsés

Heat transport in the cuprate superconductors YBa2Cu3Oy and La2−xSrxCuO4 was measured at low temperatures as a function of doping. A residual linear term κ0/T is observed throughout the superconducting region and it decreases steadily as the Mott insulator is approached from the overdoped regime. The low-energy quasiparticle gap extracted from κ0/T is seen to scale closely with the pseudogap. The ubiquitous presence of nodes and the tracking of the pseudogap shows that the overall gap remains of the pure d-wave form throughout the phase diagram, which excludes the possibility of a complex component (ix) appearing at a putative quantum phase transition and argues against a nonsuperconducting origin to the pseudogap. A comparison with superfluid density measurements reveals that the quasiparticle effective charge is weakly dependent on doping and close to unity.

Domaines: Supraconductivité [cond-mat.supr-con]

M. Sutherland, D.G. Hawthorn, R.W. Hill, F. Roning, S. Wakimoto, et al.. Thermal conductivity across the phase diagram of cuprates: low-energy quasiparticles and doping dependence of the superconducting gap. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2003, 67, pp.174520. ⟨10.1103/PhysRevB.67.174520⟩. ⟨hal-00015809⟩