Affiliation:
1. Department of Physics and Astronomy “A. Righi,” University of Bologna 1 , via Irnerio 46, 40126 Bologna, Italy
2. Department of Physics “A. Pontremoli,” University of Milan 2 , via Celoria 16, 20133 Milan, Italy
Abstract
We present an analytically solvable theory of Bardeen-Cooper-Schrieffer-type superconductivity in good metals which are confined along one of the three spatial directions, such as thin films. Closed-form expressions for the dependence of the superconducting critical temperature Tc as a function of the confinement size L are obtained, in quantitative agreement with experimental data with no adjustable parameters. Upon increasing the confinement, a crossover from a spherical Fermi surface, which contains two growing hollow spheres corresponding to states forbidden by confinement, to a strongly deformed Fermi surface, is predicted. This crossover represents a new topological transition, driven by confinement, between two Fermi surfaces belonging to two different homotopy classes. This topological transition provides a mechanistic explanation of the commonly observed non-monotonic dependence of Tc upon film thickness with a maximum which, according to our theory, coincides with the topological transition.
Funder
Army Research Office
HORIZON EUROPE European Research Council
Subject
General Physics and Astronomy
Cited by
2 articles.
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