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Title: Theory of interaction effects in normal-metal{endash}superconductor junctions out of equilibrium

Abstract

We consider a normal-metal{endash}superconductor (N-S) junction in the regime when electrons in the normal metal are driven out of equilibrium. We show that the nonequilibrium fluctuations of the electron density in the N layer cause the fluctuations of the phase of the order parameter in the S layer. As a result, the density of states in the superconductor deviates from the BCS form; most notably the density of states in the gap becomes finite. This effect can be viewed as a result of the time-reversal symmetry breaking due to the nonequilibrium, and can be described in terms of a low-energy collective mode of the junction, which couples normal currents in N-layer current and supercurrent. This mode is analogous to the Schmid-Sch{umlt o}n mode. To interpret their measurements of the tunneling current, Pothier {ital et al.} [Phys. Rev. Lett. {bold 79}, 3490 (1997)] had to assume that the energy relaxation rate in the normal metal is surprisingly high. The broadening of the BCS singularity of the density of states in the S layer manifests itself similarly to the broadening of the distribution function. The mechanism suggested here can be a possible explanation of this experimental puzzle. We also propose an independentmore » experiment to test our explanation. {copyright} {ital 1999} {ital The American Physical Society}« less

Authors:
;  [1];  [2]
  1. Department of Physics and Astronomy, SUNY Stony Brook, Stony Brook, New York 11794 (United States)
  2. Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States)|[NEC Research Institute, 4 Independence Way, Princeton, New Jersey 08540 (United States)
Publication Date:
OSTI Identifier:
686450
Resource Type:
Journal Article
Journal Name:
Physical Review, B: Condensed Matter
Additional Journal Information:
Journal Volume: 60; Journal Issue: 10; Other Information: PBD: Sep 1999
Country of Publication:
United States
Language:
English
Subject:
66 PHYSICS; SUPERCONDUCTING JUNCTIONS; SUPERCONDUCTING DEVICES; ELECTRON DENSITY; METALS; ENERGY GAP; FLUCTUATIONS; ELECTRONIC STRUCTURE; ENERGY-LEVEL DENSITY; LAYERS; BCS THEORY

Citation Formats

Narozhny, B.N., Aleiner, I.L., and Altshuler, B.L. Theory of interaction effects in normal-metal{endash}superconductor junctions out of equilibrium. United States: N. p., 1999. Web. doi:10.1103/PhysRevB.60.7213.
Narozhny, B.N., Aleiner, I.L., & Altshuler, B.L. Theory of interaction effects in normal-metal{endash}superconductor junctions out of equilibrium. United States. doi:10.1103/PhysRevB.60.7213.
Narozhny, B.N., Aleiner, I.L., and Altshuler, B.L. Wed . "Theory of interaction effects in normal-metal{endash}superconductor junctions out of equilibrium". United States. doi:10.1103/PhysRevB.60.7213.
@article{osti_686450,
title = {Theory of interaction effects in normal-metal{endash}superconductor junctions out of equilibrium},
author = {Narozhny, B.N. and Aleiner, I.L. and Altshuler, B.L.},
abstractNote = {We consider a normal-metal{endash}superconductor (N-S) junction in the regime when electrons in the normal metal are driven out of equilibrium. We show that the nonequilibrium fluctuations of the electron density in the N layer cause the fluctuations of the phase of the order parameter in the S layer. As a result, the density of states in the superconductor deviates from the BCS form; most notably the density of states in the gap becomes finite. This effect can be viewed as a result of the time-reversal symmetry breaking due to the nonequilibrium, and can be described in terms of a low-energy collective mode of the junction, which couples normal currents in N-layer current and supercurrent. This mode is analogous to the Schmid-Sch{umlt o}n mode. To interpret their measurements of the tunneling current, Pothier {ital et al.} [Phys. Rev. Lett. {bold 79}, 3490 (1997)] had to assume that the energy relaxation rate in the normal metal is surprisingly high. The broadening of the BCS singularity of the density of states in the S layer manifests itself similarly to the broadening of the distribution function. The mechanism suggested here can be a possible explanation of this experimental puzzle. We also propose an independent experiment to test our explanation. {copyright} {ital 1999} {ital The American Physical Society}},
doi = {10.1103/PhysRevB.60.7213},
journal = {Physical Review, B: Condensed Matter},
number = 10,
volume = 60,
place = {United States},
year = {1999},
month = {9}
}