# The conductivity and the magnetization around Tc in optimally-doped YBa$_2$Cu$_3$O$_{7-\delta}$ revisited: quantitative analysis in terms of fluctuating superconducting pairs

## TL;DR

This study provides a detailed quantitative analysis of the superconducting transition in optimally-doped YBa₂Cu₃O₇−δ, demonstrating that fluctuations and quantum localization effects can explain the observed rounding behaviors in conductivity and magnetization.

## Contribution

It offers a comprehensive comparison of experimental data with the Ginzburg-Landau theory including fluctuating pairs, advancing understanding of superconducting fluctuations near Tc in cuprates.

## Key findings

- Fluctuating pairs explain the rounding effects around Tc.
- Quantum localization influences the superconducting wavefunction.
- Ginzburg-Landau approach accurately models the data.

## Abstract

We first present detailed measurements of the rounding behavior around the superconducting transition temperature, $T_c$, 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 YBa$_2$Cu$_3$O$_{7-\delta}$ (OPT Y-123), in which the inhomogeneity effects are minimized. Then, it is presented 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 allowing at present to analyze these roundings at the quantitative level. These analyses demonstrate that the measured rounding effects around $T_c$ may be explained quantitative 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 wavefunction, is taken into account. The implications of our results on the pseudogap physics of optimally-doped cuprates are also discussed.