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Critical current fluctuations in graphene Josephson junctions
Mohammad T Haque1, Marco Will2, Matti Tomi2
1Low Temperature Laboratory, QTF Centre of Excellence, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, 00076, Aalto, Finland. mohammad.haque@aalto.fi.
Scientific Reports
|October 7, 2021
Summary
We observed 1/f noise in critical current fluctuations in graphene superconducting devices. These fluctuations, linked to the proximity-induced gap, impact device performance.
Area of Science:
- Condensed Matter Physics
- Materials Science
Background:
- Studying 1/f noise in superconducting devices is crucial for understanding device limitations.
- Graphene-based Josephson junctions offer unique properties for superconducting electronics.
Purpose of the Study:
- To investigate 1/f noise in the critical current of graphene Josephson junctions.
- To understand the origin of these fluctuations and their dependence on device parameters.
Main Methods:
- Fabrication of hexagonal boron nitride (h-BN) encapsulated monolayer graphene Josephson junctions contacted by Niobium Titanium Nitride (NbTiN) electrodes.
- Measurement of low-frequency noise in the superconducting state by tracking reflection carrier signal variations.
- Analysis of critical current fluctuations near the Dirac point.
Main Results:
- Observed 1/f noise in critical current (Ic) of the graphene junction.
- Quantified critical current fluctuations on the order of 10^-5 /Hz at 1 Hz.
- Found that noise power spectrum follows a power law, P(f) ~ f^-α, with α ≈ 1.
Conclusions:
- The observed 1/f critical current noise originates from fluctuations in the proximity-induced superconducting gap in the graphene.
- These findings highlight the importance of interface quality and gap stability for graphene-based superconducting devices.
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