Minigap Suppression in S(N/F)S Junctions

We consider a long diffusive Josephson junction where the weak link is a thin (normal metal (N)–ferromagnet (F)) bilayer (N and F form parallel links between superconductors (Ss)). We show that superconductivity in the weak link can be described by an effective one-dimensional Usadel equation contai...

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Bibliographic Details
Published in:JETP letters 2021-05, Vol.113 (10), p.631-637
Main Authors: Ioselevich, P. A., Chuklanov, D. A.
Format: Article
Language:English
Subjects:
Atomic
Bilayers
Biological and Medical Physics
Biophysics
Condensed Matter
Density of states
Ferromagnetism
Inhomogeneity
Josephson junctions
Molecular
Optical and Plasma Physics
Particle and Nuclear Physics
Physics
Physics and Astronomy
Quantum Information Technology
Solid State Physics
Spintronics
Superconductivity
Superconductors
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Summary:We consider a long diffusive Josephson junction where the weak link is a thin (normal metal (N)–ferromagnet (F)) bilayer (N and F form parallel links between superconductors (Ss)). We show that superconductivity in the weak link can be described by an effective one-dimensional Usadel equation containing a “diluted” exchange field as well as a weak depairing term that is caused by the inherent inhomogeneity of the bilayer. The depairing mechanism distinguishes the S(N/F)S system from an SFS junction and affects the density of states of the S(N/F)S junction. It results in the suppression of the minigap in the spin-resolved density of states. The depairing rate and the minigap are expressed in terms of geometrical parameters, the Thouless energy and the effective exchange field. The effective one-dimensional theory can be applied to various structures with thin inhomogeneous links and shows good agreement with numerical solutions of the original two-dimensional equations. We also discuss ways to reveal the predicted effect experimentally.
ISSN:0021-3640
1090-6487
DOI:10.1134/S0021364021100027