Structural and Tc inhomogeneities inherent to doping in La_{2-x}Sr_xCuO_4 superconductors and their effects on the precursor diamagnetism

TL;DR

This study investigates the intrinsic doping inhomogeneities in La_{2-x}Sr_xCuO_4 superconductors and their impact on precursor diamagnetism, revealing that bulk inhomogeneities explain the diamagnetic behavior above Tc within a Gaussian-Ginzburg-Landau framework.

Contribution

It demonstrates that bulk inhomogeneities due to Sr doping are sufficient to explain precursor diamagnetism, challenging surface probe measurements of inhomogeneity.

Findings

Bulk inhomogeneities are larger than surface probe estimates.

Precursor diamagnetism aligns with Gaussian-Ginzburg-Landau theory when considering inhomogeneities.

Doping inhomogeneities influence the superconducting transition characteristics.

Abstract

The inhomogeneities inherent to the random distribution of Sr dopants in La_{2-x}Sr_xCuO_4 superconductors are probed by measuring the x-ray diffraction linewidths and the Meissner transition widths, and then consistently explained on the grounds of a simple model in which the local Sr content is calculated by averaging over distances close to the in-plane electronic mean free path. By taking into account these intrinsic bulk inhomogeneities with long characteristic lengths (much larger than the superconducting coherence length amplitudes), the precursor diamagnetism measured above Tc, a fingerprint of the superconducting transition own nature, is then explained for all doping levels in terms of the conventional Gaussian-Ginzburg-Landau approach for layered superconductors. These results also suggest that the electronic inhomogeneities observed in the normal state by using surface probes overestimate the ones in the bulk.