Local superfluid densities probed via current-induced superconducting phase gradients

TL;DR

This paper introduces a superconducting phase gradiometer using DNA-templated nanowires to measure superfluid density and phase gradients, revealing effects of vortex displacements and comparing results with theoretical models.

Contribution

It presents a novel superconducting phase gradiometer device and demonstrates its capability to probe superfluid density and phase gradients under various conditions.

Findings

Observed resistance oscillations due to phase differences

Measured temperature and magnetic field dependence of superfluid density

Detected amplification of phase gradients from vortex displacements

Abstract

We have developed a superconducting phase gradiometer consisting of two parallel DNA-templated nanowires connecting two thin-film leads. We have ramped the cross current flowing perpendicular to the nanowires, and observed oscillations in the lead-to-lead resistance due to cross-current-induced phase differences. By using this gradiometer we have measured the temperature and magnetic field dependence of the superfluid density and observed an amplification of phase gradients caused by elastic vortex displacements. We examine our data in light of Miller-Bardeen theory of dirty superconductors and a microscale version of Campbell's model of field penetration.