Density of States below the Thouless Gap in a Mesoscopic SNS Junction

2000/12/31 by P. M. Ostrovsky, M. A. Skvortsov, M. V. Feigel’man +1 · 4 citations
Physics and Astronomy · #Physics of Superconductivity and Magnetism #Quantum chaos and dynamical systems #Theoretical and Computational Physics #cond-mat.mes-hall #cond-mat.supr-con

paper · pdf · doi:10.1103/physrevlett.87.027002

published as Phys. Rev. Lett. 87, 027002 (2001) · 4 pages, REVTeX

arxiv created 2001/01/04 · openalex publication_date 2001/06/22 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Quasiclassical theory predicts an existence of a sharp energy gap E_g\ensuremath∼\ensuremath\ElzxhD/L² in the excitation spectrum of a long diffusive superconductor--normal metal--superconductor (SNS) junction. We show that mesoscopic fluctuations remove the sharp edge of the spectrum, leading to a nonzero density of states (DOS) for all energies. Physically, this effect originates from the quasilocalized states in the normal metal. Technically, we use an extension of Efetov's supermatrix \ensuremathσ model for mixed NS systems. A nonzero DOS at energies E<E_g is provided by the instanton solution with broken supersymmetry.

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