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

R. N. Jabdaraghi; J. T. Peltonen; O. P. Saira; J. P. Pekola

doi:10.1063/1.4940979

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

R. N. Jabdaraghi, J. T. Peltonen, O. P. Saira, J. P. Pekola

Not published at VTT

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17 Citations (Scopus)

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.

Original language	English
Article number	042604
Journal	Applied Physics Letters
Volume	108
Issue number	4
DOIs	https://doi.org/10.1063/1.4940979
Publication status	Published - 25 Jan 2016
MoE publication type	Not Eligible

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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.",

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AU - Peltonen, J. T.

AU - Saira, O. P.

AU - Pekola, J. P.

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AB - 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.

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

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