• Open Access

Current Crowding in Nanoscale Superconductors within the Ginzburg-Landau Model

Mattias Jönsson, Robert Vedin, Samuel Gyger, James A. Sutton, Stephan Steinhauer, Val Zwiller, Mats Wallin, and Jack Lidmar
Phys. Rev. Applied 17, 064046 – Published 24 June 2022

Abstract

The current density in a superconductor with turnarounds or constrictions is nonuniform due to a geometrical current-crowding effect. This effect reduces the critical current in the superconducting structure compared to a straight segment and is of importance when designing superconducting devices. We investigate the current-crowding effect in numerical simulations within the generalized time-dependent Ginzburg-Landau (GTDGL) model. The results are validated experimentally by measuring the magnetic field dependence of the critical current in superconducting-nanowire structures, similar to those employed in single-photon detector devices. Comparing the results with London theory, we conclude that the reduction in critical current is significantly smaller in the GTDGL model. This difference is attributed to the current redistribution effect, which reduces the current density at weak points of the superconductor and counteracts the current-crowding effect. We numerically investigate the effect of the fill factor on the critical current in a meander and conclude that the reduction of the critical current is low enough to justify fill factors higher than 33% for applications where the detection efficiency is critical. Finally, we propose a meander design that can combine a high fill factor and low current crowding.

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  • Received 10 December 2021
  • Revised 10 March 2022
  • Accepted 26 April 2022

DOI:https://doi.org/10.1103/PhysRevApplied.17.064046

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI. Funded by Bibsam.

Published by the American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Mattias Jönsson1, Robert Vedin1, Samuel Gyger2, James A. Sutton2, Stephan Steinhauer2, Val Zwiller2, Mats Wallin1, and Jack Lidmar1,*

  • 1Department of Physics, KTH Royal Institute of Technology AlbaNova University Center, Stockholm SE 106 91, Sweden
  • 2Department of Applied Physics, KTH Royal Institute of Technology AlbaNova University Center, Stockholm SE 106 91, Sweden

  • *jlidmar@kth.se

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Vol. 17, Iss. 6 — June 2022

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