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.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - May 23 2003|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics