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Ballistic-like supercurrent in suspended graphene Josephson weak links
Naomi Mizuno1, Bent Nielsen, Xu Du
11] Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794-3800, USA [2].
Nature Communications
|November 15, 2013
Summary
Researchers fabricated high-quality suspended graphene-superconductor Josephson junctions, overcoming disorder issues. This breakthrough enables the study of exotic physics and novel device applications using Dirac fermions and superconductivity.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Quantum Phenomena
Background:
- Graphene's massless Dirac fermions and superconductor Cooper pairs offer potential for exotic physics and devices.
- Conventional graphene-superconductor junctions suffer from disorder, hindering new physics observation.
- Disorder causes charge scattering and potential fluctuations, limiting device performance.
Purpose of the Study:
- To overcome disorder limitations in graphene-superconductor junctions.
- To fabricate high-quality suspended graphene-superconductor junctions.
- To explore exotic physical phenomena and device applications at the graphene-superconductor interface.
Main Methods:
- Fabrication of suspended monolayer graphene-niobium nitride (NbN) Josephson junctions.
- Characterization of device mobility exceeding 150,000 cm(2)/Vs.
- Measurement of supercurrent flow at critical temperatures above 2 K.
Main Results:
- Demonstrated high-quality suspended graphene-NbN Josephson junctions.
- Achieved high device mobility and low carrier density.
- Observed supercurrent flow consistent with ballistic transport.
- Linear dependence on Fermi energy reflecting Dirac fermion dispersion.
Conclusions:
- Suspended graphene-superconductor junctions minimize disorder, enabling new physics.
- These junctions show promise for advanced quantum devices.
- The results pave the way for exploring Dirac fermion-superconductor interactions.
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