Recently gate-mediated supercurrent suppression in superconducting nano-bridges has been reported in many experiments. This could be either a direct or an indirect gate effect. The microscopic understanding of this observation is not clear till now. Using the quasiclassical Green's function method, we show that a small concentration of magnetic impurities at the surface of the bridges can significantly help to suppress superconductivity and hence the supercurrent inside the systems while applying a gate field. This is because the gate field can enhance the depairing through the exchange interaction between the magnetic impurities at the surface and the superconductor. We also obtain a \emph{symmetric} suppression of the supercurrent with respect to the gate field, a signature of a direct gate effect. Future experiments can verify our predictions by modifying the surface with magnetic impurities.
@article{arxiv.2303.07801,
title = {Microscopic theory of supercurrent suppression by gate-controlled surface depairing},
author = {Subrata Chakraborty and Danilo Nikolić and Juan Carlos Cuevas and Francesco Giazotto and Angelo Di Bernardo and Elke Scheer and Mario Cuoco and Wolfgang Belzig},
journal= {arXiv preprint arXiv:2303.07801},
year = {2023}
}