Anisotropic 3D fluctuation conductivity in Y1Ba2Cu3O7-y thin films on different substrates

In zero applied magnetic field the paraconductivity is measured in high-qua lity c-axis oriented perpendicular to the substrate epitaxial thin films of Y1Ba2Cu3O7-y, grown on LaAlO3, KTaO3, YSZ and SrTiO3 substrates. The resul ts for the two-band model formulas for the temperature dependence of the an isotropic three-dimensional (3D) paraconductivity in the vicinity of a supe rconducting phase transition are used in comparison of the theory with expe riment. We obtained reasonable values and the slope of fluctuation conducti vity, the superconducting transition temperature and the coherence length. (C) 1999 Elsevier Science B.V. All rights reserved.