Determination of material parameters from normalized fluctuation conductivity in YBa₂Cu₃O_7-x thin films

We report material parameters determined from the measurements of zero-field fluctuation resistivity on epitaxially-grown YBa₂Cu₃O_7-x thin films. In evaluation, we excluded explicitly the sample-dependent effect on the resistivity such as inhomogeneity by normalizing the resistivity using the scaling factor C introduced by Oh et al. We found that, taking this factor into account, the c-axis superconding coherence lengths for two samples with a large difference in normal state resistivity turned out quite close to each other, 1.84 Å and 1.05 Å, the magnitude itself in a close agreement with the value obtained by others. We obtained the mean field transition temperature about 0.5 K above the zero-resistance transition temperature, the result in contrary to the one obtained by Friedmann et al.