Short Ballistic Josephson Coupling in Planar Graphene Junctions with Inhomogeneous Carrier Doping

We report on short ballistic (SB) Josephson coupling in junctions embedded in a planar heterostructure of graphene. Ballistic Josephson coupling is confirmed by the Fabry-Perot-type interference of the junction critical current I_{c}. The product of I_{c} and the normal-state junction resistance R_{...

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Bibliographic Details
Published in:Physical review letters 2018-02, Vol.120 (7), p.077701-077701, Article 077701
Main Authors: Park, Jinho, Lee, Jae Hyeong, Lee, Gil-Ho, Takane, Yositake, Imura, Ken-Ichiro, Taniguchi, Takashi, Watanabe, Kenji, Lee, Hu-Jong
Format: Article
Language:English
Subjects:
Coupling
Critical current (superconductivity)
Doping
Graphene
Heterostructures
Superconductivity
Temperature dependence
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Summary:We report on short ballistic (SB) Josephson coupling in junctions embedded in a planar heterostructure of graphene. Ballistic Josephson coupling is confirmed by the Fabry-Perot-type interference of the junction critical current I_{c}. The product of I_{c} and the normal-state junction resistance R_{N}, normalized by the zero-temperature gap energy Δ_{0} of the superconducting electrodes, turns out to be exceptionally large close to 2, an indication of strong Josephson coupling in the SB junction limit. However, I_{c} shows a temperature dependence that is inconsistent with the conventional short-junction-like behavior based on the standard Kulik-Omel'yanchuk prediction. We argue that this feature stems from the effects of inhomogeneous carrier doping in graphene near the superconducting contacts, although the junction is in fact in the short-junction limit.
ISSN:0031-9007
1079-7114
DOI:10.1103/PhysRevLett.120.077701