title: Phonon limited superconducting correlations in metallic nanograins.
abstract: Conventional superconductivity is inevitably suppressed in ultra-small metallic grains for characteristic sizes smaller than the Anderson limit. Experiments have shown that above the Anderson limit the critical temperature may be either enhanced or reduced when decreasing the particle size, depending on the superconducting material. In addition, there is experimental evidence that whether an enhancement or a reduction is found depends on the strength of the electron-phonon interaction in the bulk. We reveal how the strength of the e-ph interaction interplays with the quantum-size effect and theoretically obtain the critical temperature of the superconducting nanograins in excellent agreement with experimental data. We demonstrate that strong e-ph scattering smears the peak structure in the electronic density-of-states of a metallic grain and enhances the electron mass, and thereby limits the highest Tc achievable by quantum confinement.
authors.affiliation: Departement Fysica, Universiteit Antwerpen, B-2020 Antwerpen, Belgium.
authors.forename: M D
authors.initials: MD
authors.lastname: Croitoru
authors.affiliation: Universidade Federal de Pernambuco, 50670-901 Recife, Pernambuco, Brazil.
authors.forename: A A
authors.initials: AA
authors.lastname: Shanenko
authors.affiliation: Theoretische Physik III, Universität Bayreuth, 95440 Bayreuth, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Vagov
authors.affiliation: Departement Fysica, Universiteit Antwerpen, B-2020 Antwerpen, Belgium.
authors.forename: M V
authors.initials: MV
authors.lastname: Milošević
authors.affiliation: Theoretische Physik III, Universität Bayreuth, 95440 Bayreuth, Germany.
authors.forename: V M
authors.initials: VM
authors.lastname: Axt
authors.affiliation: Departement Fysica, Universiteit Antwerpen, B-2020 Antwerpen, Belgium.
authors.forename: F M
authors.initials: FM
authors.lastname: Peeters