BCS superconductivity in metallic nanograins: Finite-size corrections, low-energy excitations, and robustness of shell effects

Antonio M. García-García, Juan Diego Urbina, Emil A. Yuzbashyan, Klaus Richter, Boris L. Altshuler

Research output: Contribution to journalArticlepeer-review

35 Scopus citations

Abstract

We combine the BCS self-consistency condition, a semiclassical expansion for the spectral density and interaction matrix elements to describe analytically how the superconducting gap depends on the size and shape of a two- and three-dimensional superconducting grain. In chaotic grains mesoscopic fluctuations of the matrix elements lead to a smooth dependence of the order parameter on the excitation energy. In the integrable case we find shell effects; i.e., for certain values of the electron number N a small change in N leads to large changes in the energy gap. With regard to possible experimental tests we provide a detailed analysis of the dependence of the gap on the coherence length and the robustness of shell effects under small geometrical deformations.

Original languageEnglish (US)
Article number014510
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume83
Issue number1
DOIs
StatePublished - Jan 20 2011

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

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