In-plane electronic thermal conductivity of layered d-wave high-T-c superconductors

The temperature dependence of the in-plane electronic contribution to the thermal conductivity of a d-wave superconductor is calculated within a variational method from low to high temperature. To account for the layered structure of high-T-c compounds, we consider an anisotropic Lawrence-Doniach energy spectrum for electrons. The very low temperature behavior of the thermal conductivity of most high-T-c superconductors as well as the peak structure observed below T-c are quantitatively reproduced by this model. These results both suggest that the symmetry of the order parameter of high-T-c superconductors is of d(x)2-(y)2-wave type and concur with the hypothesis that the peak observed in the thermal conductivity of these materials has an electronic origin.