Influence of the atomic scale inhomogeneity of the pair interaction on the local pair formation and density of states in high-T_c superconductors

TL;DR

This paper investigates how atomic-scale inhomogeneities in pairing interactions affect local superconducting properties and the density of states, revealing a nearly universal ratio of gap to transition temperature that aligns with experimental observations.

Contribution

It demonstrates that local inhomogeneities lead to a consistent ratio of gap to transition temperature, independent of perturbation concentration, within a mean-field BCS framework.

Findings

The ratio 2Δg/Tp can be significantly larger than in homogeneous cases.

The ratio is nearly independent of the local perturbation concentration.

Results align with recent experimental measurements.

Abstract

The influence of the atomic-scale inhomogeneities of the pairing interaction on the superconducting order parameter distribution and the LDOS is studied in the framework of mean-field BCS theory for two-dimensional lattice model. It is found that the ratio of the local low-temperature gap in differential conductance to the local temperature of vanishing the gap $2\Delta_g/T_p$ can take large enough values compared to the homogeneous case. This ratio practically does not depend on the location in the sample and is independent on the concentration of local pair interaction perturbations in wide range of concentrations. The obtained results could bear a relation to the recent measurements by Gomes {\it et. al} Nature, 447, 569 (2007).