The conductivity and the magnetization around Tc in optimally-doped YBa2Cu3O7−δ revisited: quantitative analysis in terms of fluctuating superconducting pairs

Abstract

We first present detailed measurements of the rounding behavior around the superconducting transition temperature, Tc, of the in-plane electrical conductivity, magnetoconductivity and magnetization, including the low and moderate magnetic field regimes, in a high-quality single crystal and a thin film of the prototypical optimally-doped YBa2Cu3O7-δ (OPT Y-123), in which the inhomogeneity effects are minimized. Then, we present a comparison of these experimental data with the phenomenological Ginzburg–Landau (GL) approach that takes into account the unavoidable contribution of the fluctuating pairs, the only theoretical scenario that at present allows analysis of these roundings at the quantitative level. These analyses demonstrate that the measured rounding effects around Tc may be explained quantitatively and consistently in terms of the GL scenario, even up to the rounding onset temperatures if the quantum localization, associated with the shrinkage of the superconducting wave function, is taken into account. The implications of our results on the pseudogap physics of optimally-doped cuprates are also discussed.