On the Magnetic Penetration Depth in Superconducting Ultrathin Lead Films
A.P. Durajski and R. Szczęśniak
Institute of Physics, Częstochowa University of Technology, Av. Armii Krajowej 19, 42-200 Częstochowa, Poland
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In the present paper, we report a theoretical study of the magnetic London penetration depth in ultrathin Pb films consisting of five to ten monolayers. Our calculations were performed within the framework of the strong-coupling approach. We observed that for thin films, the thermodynamic parameter exhibits an oscillatory behaviour connected with a quantum size effect. Moreover, we proved that the London penetration depth of Pb films cannot be correctly described using the Bardeen-Cooper-Schrieffer theory of superconductivity due to the strong-coupling and retardation effects. The Eliashberg theory, used in this paper, goes beyond the BCS theory to include these effects which allows to describe the superconducting state on the quantitative level.

DOI: 10.12693/APhysPolA.131.1051
PACS numbers: 74.20.Fg, 74.25.Bt, 74.62.Fj