INPLANE 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 with in a variational method from low to high temperature. To account for t he layered structure of high-T-c compounds, we consider an anisotropic Lawrence-Doniach energy spectrum for electrons. The very low temperat ure behavior of the thermal conductivity of most high-T-c superconduct ors as well as the peak structure observed below T-c are quantitativel y reproduced by this model. These results both suggest that the symmet ry 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 th e thermal conductivity of these materials has an electronic origin.