Electronic contribution to the thermal diffusivity: DyBa2Cu3O7-y and Y0.9Ca0.1Ba2Cu3O7-z

The electronic contribution to the specific heat and the thermal conductivity of high-T-c superconductors is calculated with a three-dimensional band structure including saddle points and a Lawrence-Doniach coupling between the CuO2 planes. The electronic thermal diffusivity is deduced for s- and d-wave symmetry of the order parameter. Data on DyBa2Cu3O7-y and Y0.9Ca0.1Ba2Cu3O7-z and theory are in good agreement on the change of the slope near T-c.