Precursor superconducting effects in the optimally doped YBa$_2$Cu$_3$O$_{7-\delta}$ superconductor: the confrontation between superconducting fluctuations and percolative effects revisited

Abstract

The confrontation between the superconducting fluctuations and percolation effects as the origin of the in-plane paraconductivity in cuprate superconductors was earlier addressed at a quantitative level in the case of the optimally doped YBa$_2$Cu$_3$O$_{7-\delta}$ (YBCO) compound. Using in-plane resistivity data from a high-quality YBCO thin film, we will extend these analyses to high reduced temperatures, in the case of the Gaussian-Ginzburg-Landau (GGL) approach for the conventional superconducting fluctuations, by considering the total energy cutoff. These data will also be analysed in terms of the mean field-approach of the effective-medium theory, to probe if emergent percolative effects may account for the resistivity rounding above $T_c$. Our analyses confirm earlier conclusions: the measured paraconductivity cannot be explained in terms of emergent percolation processes, but it may be accounted for in terms of the GGL approach. These results also call into question alternative scenarios, including a recent proposal derived from emergent percolative effects.