TRANSITION-TEMPERATURE FEATURES OF LAYERED SUPERCONDUCTORS

A model theory for the superconducting transition temperature T-c is d erived that is based on a generalized version of the Eliashberg equati ons taking into account an energy dependence in the electronic density of states N(epsilon). We treat an electronic structure with character istic two-dimensional character. An analytical expression for T-c obta ined for intermediate coupling establishes features of the T-c in the logarithmic van Hove scenario. Results describe the behavior of T-c vs x observed in well-annealed La2-xSrxCuO4 oxides.