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.
@article{arxiv.2107.00935,
title = {Electrostatic field-driven supercurrent suppression in ionic-gated metallic Josephson nanotransistors},
author = {Federico Paolucci and Francesco Crisà and Giorgio De Simoni and Lennart Bours and Claudio Puglia and Elia Strambini and Stefano Roddaro and Francesco Giazotto},
journal= {arXiv preprint arXiv:2107.00935},
year = {2025}
}