Calculation of the effect of random superfluid density on the temperature dependence of the penetration depth

TL;DR

This paper models how nanoscale inhomogeneity in superfluid density affects the temperature dependence of magnetic penetration depth in superconductors, highlighting the importance of considering disorder effects in measurements.

Contribution

It introduces a generalized London equation approach to account for non-uniform superfluid density and derives how disorder influences the effective penetration depth.

Findings

Effective penetration depth differs from the average due to disorder.

Results emphasize caution in interpreting penetration depth measurements in inhomogeneous systems.

Sensitivity of penetration depth to disorder details affects temperature dependence analysis.

Abstract

Microscopic variations in composition or structure can lead to nanoscale inhomogeneity in superconducting properties such as the magnetic penetration depth, but measurements of these properties are usually made on longer length scales. We solve a generalized London equation with a non-uniform penetration depth, lambda(r), obtaining an approximate solution for the disorder-averaged Meissner effect. We find that the effective penetration depth is different from the average penetration depth and is sensitive to the details of the disorder. These results indicate the need for caution when interpreting measurements of the penetration depth and its temperature dependence in systems which may be inhomogeneous.