Title:CONSTRAINTS ON POSSIBLE MECHANISMS FOR HIGH-T_c SUPERCONDUCTIVITY
Authors:E.Schachinger, I.Schurrer (Institut fur Theoretische Physik, Technische Universitat Graz, Petersgasse 16, A-8010 Graz, Austria)

This paper discusses a phenomenological model used to describe various properties of a d_x²-y² superconductor in its temperature as well as frequency dependence, namely, the London penetration depth, the optical conductivity, the microwave conductivity, and the electronic thermal conductivity. We assume the CuO₂ planes to be the dominant feature for superconductivity and develop a 2D-formalism in which inelastic scattering is modelled explicitly by a spectral density which describes a fluctuation spectrum responsible for the superconducting transition and also for the large inelastic scattering observed in the normal state above the critical temperature T_c. The feedback effect of superconductivity on the spectral density is modelled by a temperature dependent low frequency cutoff. Theoretical results are compared with the experimental data and the fact that such a model allows a consistent description of a variety of phenomena is then used to formulate constraints on possible mechanisms of superconductivity in oxides.

Key words: high- T_c superconductivity, London penetration depth, optical conductivity, electronic thermal conductivity
Comments: Figs. 7, Refs. 34, Tabs. 0.