THEORY OF THERMAL-CONDUCTIVITY AND NUCLEAR-RELAXATION RATE FOR HIGH-TEMPERATURE SUPERCONDUCTORS

We solve the strong-coupling equations for the self-energy of electrons in a two-dimensional tight-binding band, interacting via exchange of phonons, charge fluctuations, and spin fluctuations. The resulting dynamical spin and charge susceptibilities yield the nuclear spin-lattice relaxation rate 1/T1 and the phonon thermal conductivity K(p). For realistic values of the electron-phonon coupling lambda(ph) and the on-site Coulomb interaction U/tBAR we obtain a high T(c), a rapid drop of 1/T1 below T(c), and a broad peak in kappa(p) below T(c). The electronic thermal conductivity kappa(e) is almost constant above T(c), and it exhibits also a peak below T(c) due to combined effects of inelastic and elastic electron scattering. Our results are in fair agreement with the actually measured quantities in Cu-O plane superconductors.