Universal relationship between the penetration depth and the normal-state conductivity in YBaCuO

TL;DR

This paper reveals a universal correlation between the normal-state conductivity and the penetration depth in YBaCuO superconductors, enabling predictions of superconducting properties from normal-state measurements.

Contribution

It establishes a universal relationship between conductivity and penetration depth in YBaCuO, independent of doping or defects, offering a new predictive method.

Findings

Strong correlation between sigma_n and 1/lambda^2 across samples

Universal relationship holds regardless of doping or defects

Provides a simple method to estimate superconducting properties

Abstract

The absolute values of the conductivity in the normal state sigma_n and of the low temperature penetration depths lambda(0) were measured for a number of different samples of the YBaCuO family. We found a striking correlation between sigma_n and 1/lambda^2, regardless of doping, oxygen reduction or defects, thus providing a simple method to predict the superconducting penetration depth and to have an estimate of the sample quality by measuring the normal-state conductivity.