Electrostatic field-driven supercurrent suppression in ionic-gated metallic Josephson nanotransistors

TL;DR

This paper demonstrates that static electrostatic fields can significantly suppress supercurrent in ionic-gated superconducting nanotransistors without electron injection, challenging traditional charge-based explanations.

Contribution

It provides conclusive experimental evidence for electrostatic control of supercurrent in superconductors, introducing a new understanding of electric field effects on superconductivity.

Findings

Supercurrent suppression up to 45% in Nb ISFETs

Bipolar supercurrent suppression observed

Critical temperature and resistance remain unchanged

Abstract

Recent experiments have shown the possibility of tuning the transport properties of metallic nanosized superconductors through a gate voltage. These results renewed the longstanding debate on the interaction between electrostatic fields and superconductivity. Indeed, different works suggested competing mechanisms as the cause of the effect: an unconventional electric field-effect or quasiparticle injection. Here, we provide conclusive evidence for the electrostatic-field-driven control of the supercurrent in metallic nanosized superconductors, by realizing ionic-gated superconducting field-effect nanotransistors (ISFETs) where electron injection is impossible. Our Nb ISFETs show giant suppression of the superconducting critical current of up to 45%. Moreover, the bipolar supercurrent suppression observed in different ISFETs, together with invariant critical temperature and normal-state resistance, also excludes conventional charge accumulation/depletion. Therefore, the microscopic explanation of this effect calls upon a novel theory able to describe the nontrivial interaction of static electric fields with conventional superconductivity.