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Fermi Velocity Dependent Critical Current in Ballistic Bilayer Graphene Josephson Junctions
Amis Sharma1, Chun-Chia Chen2, Jordan McCourt2
1Department of Physics and Astronomy, Texas A&M University, College Station, Texas 77843, United States.
ACS Nanoscience Au
|April 21, 2025
Summary
We studied bilayer graphene Josephson junctions and found their critical current depends exponentially on temperature. This dependence allows tuning the Fermi velocity and carrier density, unlike single-layer graphene devices.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Electronics
Background:
- Bilayer graphene Josephson junctions (BGJJs) are promising for electronic devices.
- Understanding their transport properties is crucial for advanced applications.
Purpose of the Study:
- Investigate the temperature and carrier density dependence of BGJJs.
- Determine the Fermi velocity in bilayer graphene.
- Compare BGJJs with single-layer graphene Josephson junctions.
Main Methods:
- Transport measurements on proximitized, ballistic BGJJs.
- Differential resistance measurements as a function of bias current and gate voltage.
- Analysis of critical current (Ic) temperature dependence.
Main Results:
- Critical current follows an exponential temperature trend: exp(-kB*T/δE).
- Extracted Fermi velocity increases with gate voltage.
- δE shows carrier density dependence due to bilayer graphene's quadratic dispersion.
Conclusions:
- Bilayer graphene Josephson junctions offer tunable Fermi velocity and carrier density.
- This contrasts with single-layer graphene, providing new control parameters for devices.
- Findings advance the development of graphene-based superconducting electronics.
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