title: Superconducting parity effect across the Anderson limit.
abstract: How small can superconductors be? For isolated nanoparticles subject to quantum size effects, P.W. Anderson in 1959 conjectured that superconductivity could only exist when the electronic level spacing δ is smaller than the superconducting gap energy Δ. Here we report a scanning tunnelling spectroscopy study of superconducting lead (Pb) nanocrystals grown on the (110) surface of InAs. We find that for nanocrystals of lateral size smaller than the Fermi wavelength of the 2D electron gas at the surface of InAs, the electronic transmission of the interface is weak; this leads to Coulomb blockade and enables the extraction of electron addition energy of the nanocrystals. For large nanocrystals, the addition energy displays superconducting parity effect, a direct consequence of Cooper pairing. Studying this parity effect as a function of nanocrystal volume, we find the suppression of Cooper pairing when the mean electronic level spacing overcomes the superconducting gap energy, thus demonstrating unambiguously the validity of the Anderson criterion.
authors.affiliation: LPEM, ESPCI Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC University of Paris 6, 10 rue Vauquelin, Paris F-75005, France.
authors.forename: Sergio
authors.identifier: 0000-0002-2297-8574
authors.initials: S
authors.lastname: Vlaic
authors.affiliation: LPEM, ESPCI Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC University of Paris 6, 10 rue Vauquelin, Paris F-75005, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Pons
authors.affiliation: LPEM, ESPCI Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC University of Paris 6, 10 rue Vauquelin, Paris F-75005, France.
authors.forename: Tianzhen
authors.initials: T
authors.lastname: Zhang
authors.affiliation: LPEM, ESPCI Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC University of Paris 6, 10 rue Vauquelin, Paris F-75005, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Assouline
authors.affiliation: LPEM, ESPCI Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC University of Paris 6, 10 rue Vauquelin, Paris F-75005, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Zimmers
authors.affiliation: Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Universités Paris-Saclay, C2N-Marcoussis, Marcoussis 91460, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: David
authors.affiliation: Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Universités Paris-Saclay, C2N-Marcoussis, Marcoussis 91460, France.
authors.forename: Guillemin
authors.initials: G
authors.lastname: Rodary
authors.affiliation: Centre de Nanosciences et de Nanotechnologies, CNRS, Univ. Paris-Sud, Universités Paris-Saclay, C2N-Marcoussis, Marcoussis 91460, France.
authors.forename: Jean-Christophe
authors.initials: JC
authors.lastname: Girard
authors.affiliation: LPEM, ESPCI Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC University of Paris 6, 10 rue Vauquelin, Paris F-75005, France.
authors.forename: Dimitri
authors.initials: D
authors.lastname: Roditchev
authors.affiliation: LPEM, ESPCI Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC University of Paris 6, 10 rue Vauquelin, Paris F-75005, France.
authors.forename: Hervé
authors.initials: H
authors.lastname: Aubin