Influence of inelastic quasiparticle scattering on thermodynamic and transport properties of high-T-c oxides

The superconducting order parameter Delta and energy gap Delta(g) are calculated taking into account the pair-breaking inelastic quasiparticle scattering by thermal Bose excitations, e.g. phonons. The treatment is self-consistent because the scattering amplitude depends on Delta. The superconducting transition for any strength of the inelastic scattering is the phase transition of the first kind and the dependences Delta(T) and Delta(g)(T) tend to rectangular curves that agree well with tunnel, point-contact infrared and Raman spectroscopy measurements for high-T-c oxides. On the basis of the developed theory, the critical Josephson tunnel current, ultrasound attenuation, electron thermal conductivity, and nuclear spin-lattice relaxation rate R(s) in the superconducting state are calculated. All of these quantities are shown to decrease abruptly below T-c. In particular, the Hebel-Slichter peak in R(s)(T) disappears for strong enough inelastic scattering, although the energy gap in the quasiparticle spectrum is retained.