Gate control of superconductivity in mesoscopic all-metallic devices

TL;DR

This paper investigates the mechanism behind gate-controlled superconductivity in mesoscopic metallic devices, providing experimental and simulation evidence that challenges the thermal origin hypothesis and explores potential applications.

Contribution

It offers a comprehensive analysis of the gating effect in metallic superconductors, combining experimental results and simulations to suggest a non-thermal mechanism.

Findings

Gate control can suppress supercurrent in titanium wires.

Thermal origin of the effect is unlikely based on probability distributions.

Finite element simulations support a non-thermal switching mechanism.

Abstract

It was recently demonstrated the possibility to tune, through the application of a control gate voltage, the superconducting properties of mesoscopic devices based on Bardeen-Cooper-Schrieffer metals. In spite of the several experimental evidence obtained on different materials and geometries, a description of the microscopic mechanism at the basis of such unconventional effect has not been provided yet. This work discusses the technological potential of gate control of superconductivity in metallic superconductors and revises the experimental results which provide information regarding a possible thermal origin of the effect: in the first place, we review experiments performed on high critical temperature elemental superconductors (niobium and vanadium) and show how devices based on these materials can be exploited to realize basic electronic tools such as, e. g., a half-wave rectifier. In a second part, we discuss the origin of the gating effect by showing the gate-driven suppression of the supercurrent in a suspended titanium wire and by providing a comparison between thermal and electric switching current probability distributions. Furthermore, we discuss the cold field-emission of electrons from the gate by means of finite element simulations and compare the results with experimental data. Finally, the presented data provide a strong indication regarding the unlikelihood of thermal origin of the gating effect.