Probing the pseudogap phase of cuprates by a Giaever transformer

TL;DR

This paper presents a theory of rectification effects in double-layer systems with superconductors or normal metals, showing how Coulomb interactions and fluctuations influence drag conductivity and can distinguish underlying mechanisms.

Contribution

It introduces a theoretical framework for understanding rectification in layered superconducting systems, highlighting the role of Coulomb interactions and fluctuations.

Findings

Superconducting fluctuations significantly enhance drag conductivity.

Rectification is most pronounced when both layers are superconductors.

Giaever transformer measurements can differentiate between pair fluctuations and vortex coupling.

Abstract

We develop a theory of the rectification effect in a double-layer system where both layers are superconductors, or one of the layers is a normal metal. The Coulomb interaction is assumed to provide the dominant coupling between the layers. We find that superconducting fluctuations strongly enhance the drag conductivity, with rectification most pronounced when both layers are superconductors. In view of their distinct dependence on temperature near Tc and layer separation, drag measurements based on a Giaever transformer could distinguish whether rectification occurs due to fluctuating pairs or inductively coupled fluctuating vortices.