Influence of a magnetic yield on the thermal conductivity of d-wave high-T-c superconductors

The influence of a magnetic field on the electronic contribution kappa(e) to the thermal conductivity of a d-wave superconductor is described. We use the kinetic expression for kappa(e) in terms of a number of carriers deduced from the electronic specific heat of a d-wave superconductor. We calculate the field and temperature dependence of the scattering rate of normal heat-carrying electrons scattered by quasi-particle excitations in the 2D-like vortex cores. Near T-c, the experimental results on various YBa2Cu3O7-delta and Bi2Sr2CaCu2O8 samples are quite well reproduced by this model, as in the s-wave case with a small difference between the deduced physical parameters. However, experimental results on the field dependence of the thermal conductivity at very low temperatures are shown to be incompatible with an s-wave gap parameter but can be explained by considering a d-wave order parameter. More reasonable parameter values are found herein.