Transverse resistance due to electronic inhomogeneities in superconductors

TL;DR

This paper demonstrates that electronic inhomogeneities in superconductors lead to a measurable transverse resistance at the transition, revealing macroscopic effects of microscopic spatial variations.

Contribution

It uncovers the presence of electronic inhomogeneities affecting current distribution and transverse resistance in superconducting films at the transition.

Findings

Current paths become highly non-uniform at the superconducting transition.

A finite transverse resistance develops due to electronic inhomogeneities.

The phenomenon is observed in conventional superconductors regardless of structural properties.

Abstract

Phase transitions in many-body systems are often associated with the emergence of spatial inhomogeneities. Such features may develop at microscopic lengthscales and are not necessarily evident in measurements of macroscopic quantities. In this work, we address the topic of distribution of current paths in superconducting films. Typical lengthscales associated with superconductivity are in the range of nanometres. Accordingly, measurements of electrical resistance over much larger distances are supposed to be insensitive to details of spatial inhomogeneities of electronic properties. We observe that, contrary to expectations, current paths adopt a highly non-uniform distribution at the onset of the superconducting transition which is manifested in the development of a finite transverse resistance. The anisotropic distribution of current density is unrelated to the structural properties of the superconducting films, and indicates the emergence of electronic inhomogeneities perceivable over macroscopic distances. Our experiments reveal the ubiquitous nature of this phenomenon in conventional superconductors.