Simulation of experimental results on high-T-c superconductors: A phenomenological model

A model based on a conductance expressed as a superposition of two BCS-like contributions and a linear one is proposed for the analysis of the tunneling spectra of the 90 and 60 K phases of the YBaCuO compounds. A consistent explanation of the experiments, supported by satisfactory quantitative fittings of the experimental data in both the superconducting and the normal state, is presented with a careful study of the role played by the linear term. The possible extension of the model to other copper-oxide superconductors is also discussed. Referring to a simplified one-gap version of the model, theoretical results concerning the behavior of the specific heat and the ultrasonic attenuation coefficients are found to be in good qualitative agreement with the experiments.