Microscopic theory of supercurrent suppression by gate-controlled surface depairing

• Published in: arXiv.org
• Main Authors: Chakraborty, Subrata, Nikolić, Danilo, Cuevas, Juan Carlos, Giazotto, Francesco, Angelo Di Bernardo, Scheer, Elke, Cuoco, Mario, Belzig, Wolfgang
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 14.11.2023
• Subjects: Bridges; Control surfaces; Green's functions; Impurities; Physics - Mesoscale and Nanoscale Physics; Superconductivity
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2303.07801

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.