Controllable Andreev Bound States in Bilayer Graphene Josephson Junctions from Short to Long Junction Limits

We demonstrate that the mode number of Andreev bound states in bilayer graphene Josephson junctions can be modulated by controlling the superconducting coherence length in situ. By exploiting the quadratic band dispersion of bilayer graphene, we control the Fermi velocity and thus the coherence leng...

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Bibliographic Details
Published in:Physical review letters 2024-05, Vol.132 (22), p.226301, Article 226301
Main Authors: Park, Geon-Hyoung, Lee, Wonjun, Park, Sein, Watanabe, Kenji, Taniguchi, Takashi, Cho, Gil Young, Lee, Gil-Ho
Format: Article
Language:English
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Summary:We demonstrate that the mode number of Andreev bound states in bilayer graphene Josephson junctions can be modulated by controlling the superconducting coherence length in situ. By exploiting the quadratic band dispersion of bilayer graphene, we control the Fermi velocity and thus the coherence length via the application of electrostatic gating. Tunneling spectroscopy of the Andreev bound states reveals a crossover from short to long Josephson junction regimes as we approach the charge neutral point of the bilayer graphene. Furthermore, analysis of different mode numbers of the Andreev energy spectrum allows us to estimate the phase-dependent Josephson current quantitatively. Our Letter provides a new way for studying multimode Andreev levels by tuning the Fermi velocity.
ISSN:0031-9007
1079-7114
1079-7114
DOI:10.1103/PhysRevLett.132.226301