Critical current fluctuations in graphene Josephson junctions

Journal article (2021)

Authors

Mohammad T. Haque Aalto University
Marco Will Aalto University
Matti Tomi Aalto University
Preeti Pandey Aalto University
Manohar Kumar Aalto University
F.E. Schmidt Kavli institute of nanoscience Delft, QN/Steele Lab - AS
Kenji Watanabe National Institute for Materials Science
Takashi Taniguchi National Institute for Materials Science
G.A. Steele Kavli institute of nanoscience Delft, QN/Steele Lab - AS
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Research Group
QN/Steele Lab (AS) (TU Delft)
Copyright: © 2021 Mohammad T. Haque, Marco Will, Matti Tomi, Preeti Pandey, Manohar Kumar, F.E. Schmidt, Kenji Watanabe, Takashi Taniguchi, G.A. Steele, More Authors
DOI
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https://doi.org/10.1038/s41598-021-99398-3
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Published Date

2021

Language

English

Faculty

Applied Sciences

Department

QN/Quantum Nanoscience

Research Group

QN/Steele Lab

Abstract

We have studied 1/f noise in critical current Ic in h-BN encapsulated monolayer graphene contacted by NbTiN electrodes. The sample is close to diffusive limit and the switching supercurrent with hysteresis at Dirac point amounts to ≃ 5 nA. The low frequency noise in the superconducting state is measured by tracking the variation in magnitude and phase of a reflection carrier signal vrf at 600–650 MHz. We find 1/f critical current fluctuations on the order of δIc/ Ic≃ 10 - 3 per unit band at 1 Hz. The noise power spectrum of critical current fluctuations SIc measured near the Dirac point at large, sub-critical rf-carrier amplitudes obeys the law SIc/Ic2=a/fβ where a≃ 4 × 10 - 6 and β≃ 1 at f> 0.1 Hz. Our results point towards significant fluctuations in Ic originating from variation of the proximity induced gap in the graphene junction.