Negative electrohydrostatic pressure between superconducting bodies

TL;DR

This paper predicts a negative pressure between superconducting bodies using a hydrodynamic model, aligning better with experimental data and offering new insights into superconducting interactions at nanoscales.

Contribution

It introduces a hydrodynamic approach to scalar electrodynamics for superconductors, predicting attractive forces and surface energies consistent with experiments, surpassing traditional theories.

Findings

Negative pressure of tens of N/mm^2 at angstrom separations

Better agreement with experimental surface energies

Electric-field screening length similar to Thomas-Fermi theory

Abstract

By applying a hydrodynamic representation of non-relativistic scalar electrodynamics to the superconducting order parameter, we predict a negative (attractive) pressure between planar superconducting bodies. For conventional superconductors with London penetration depth $\lambda_\text{L} \approx 100 \text{ nm}$, the pressure reaches tens of $\text{N/mm}^2$ at angstrom separations. The resulting surface energies are in better agreement with experimental values than those predicted by the Hartree-Fock theory, and the emergent electric-field screening length is comparable to that of the Thomas-Fermi theory. The model circumvents the bulk limitations of the Bardeen-Cooper-Schrieffer and Ginzburg-Landau theories to the analysis of superconducting quantum devices.