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Title: Low-temperature characterization of Nb-Cu-Nb weak links with Ar ion-cleaned interfaces

Abstract

We characterize niobium-based lateral Superconductor (S)–Normal metal (N)–Superconductor (SNS) weak links through low-temperature switching current measurements and tunnel spectroscopy. We fabricate the SNS devices in two separate lithography and deposition steps, combined with strong argon ion cleaning before the normal metal deposition in the last step. Our SNS weak link consists of high-quality sputtered Nb electrodes that have contacted with evaporated Cu. The two-step fabrication flow enables more flexibility in the choice of materials and pattern design. A comparison of the temperature-dependent equilibrium critical supercurrent with theoretical predictions indicates that the quality of the Nb-Cu interface is similar to that of evaporated Al-Cu weak links. We further demonstrate a hybrid magnetic flux sensor based on an Nb-Cu-Nb SNS junction, where the phase-dependent normal metal density of states is probed with an Al tunnel junction.

Authors:
; ;  [1]
  1. Low Temperature Laboratory, Department of Applied Physics, Aalto University School of Science, P.O. Box 13500, FI-00076 Aalto (Finland)
Publication Date:
OSTI Identifier:
22489368
Resource Type:
Journal Article
Journal Name:
Applied Physics Letters
Additional Journal Information:
Journal Volume: 108; Journal Issue: 4; Other Information: (c) 2016 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0003-6951
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ARGON IONS; DENSITY OF STATES; DEPOSITION; INTERFACES; MAGNETIC FLUX; NIOBIUM; SPECTROSCOPY; SPUTTERING; SUPERCONDUCTORS; TEMPERATURE DEPENDENCE; TUNNEL EFFECT

Citation Formats

Jabdaraghi, R. N., E-mail: robab.najafi.jabdaraghi@aalto.fi, Faculty of Physics, University of Tabriz, 51665-163 Tabriz, Peltonen, J. T., Saira, O. -P., and Pekola, J. P. Low-temperature characterization of Nb-Cu-Nb weak links with Ar ion-cleaned interfaces. United States: N. p., 2016. Web. doi:10.1063/1.4940979.
Jabdaraghi, R. N., E-mail: robab.najafi.jabdaraghi@aalto.fi, Faculty of Physics, University of Tabriz, 51665-163 Tabriz, Peltonen, J. T., Saira, O. -P., & Pekola, J. P. Low-temperature characterization of Nb-Cu-Nb weak links with Ar ion-cleaned interfaces. United States. https://doi.org/10.1063/1.4940979
Jabdaraghi, R. N., E-mail: robab.najafi.jabdaraghi@aalto.fi, Faculty of Physics, University of Tabriz, 51665-163 Tabriz, Peltonen, J. T., Saira, O. -P., and Pekola, J. P. 2016. "Low-temperature characterization of Nb-Cu-Nb weak links with Ar ion-cleaned interfaces". United States. https://doi.org/10.1063/1.4940979.
@article{osti_22489368,
title = {Low-temperature characterization of Nb-Cu-Nb weak links with Ar ion-cleaned interfaces},
author = {Jabdaraghi, R. N., E-mail: robab.najafi.jabdaraghi@aalto.fi and Faculty of Physics, University of Tabriz, 51665-163 Tabriz and Peltonen, J. T. and Saira, O. -P. and Pekola, J. P.},
abstractNote = {We characterize niobium-based lateral Superconductor (S)–Normal metal (N)–Superconductor (SNS) weak links through low-temperature switching current measurements and tunnel spectroscopy. We fabricate the SNS devices in two separate lithography and deposition steps, combined with strong argon ion cleaning before the normal metal deposition in the last step. Our SNS weak link consists of high-quality sputtered Nb electrodes that have contacted with evaporated Cu. The two-step fabrication flow enables more flexibility in the choice of materials and pattern design. A comparison of the temperature-dependent equilibrium critical supercurrent with theoretical predictions indicates that the quality of the Nb-Cu interface is similar to that of evaporated Al-Cu weak links. We further demonstrate a hybrid magnetic flux sensor based on an Nb-Cu-Nb SNS junction, where the phase-dependent normal metal density of states is probed with an Al tunnel junction.},
doi = {10.1063/1.4940979},
url = {https://www.osti.gov/biblio/22489368}, journal = {Applied Physics Letters},
issn = {0003-6951},
number = 4,
volume = 108,
place = {United States},
year = {Mon Jan 25 00:00:00 EST 2016},
month = {Mon Jan 25 00:00:00 EST 2016}
}