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DOE OSTI · 3021326

Fermi Velocity Dependent Critical Current in Ballistic Bilayer Graphene Josephson Junctions

Sharma, Amis [Texas A&M University, College Station, TX (United States)] (ORCID:0000000277283753)·Chen, Chun-Chia [Duke University, Durham, NC (United States)]·McCourt, Jordan [Duke University, Durham, NC (United States)]·Kim, Mingi [Purdue University, West Lafayette, IN (United States)]·Watanabe, Kenji [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000337018119)·Taniguchi, Takashi [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000214673105)·Rokhinson, Leonid [Purdue University, West Lafayette, IN (United States)]·Finkelstein, Gleb [Duke University, Durham, NC (United States)]·Borzenets, Ivan [Texas A&M University, College Station, TX (United States)] (ORCID:0000000215778312)
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Abstract

We perform transport measurements on proximitized, ballistic, bilayer graphene Josephson junctions (BGJJs) in the intermediate-to-long junction regime (L > ξ). We measure the device’s differential resistance as a function of bias current and gate voltage for a range of different temperatures. The extracted critical current IC follows an exponential trend with temperature: exp(−k B T/δE). Here δE = ħν F /2πL: an expected trend for intermediate-to-long junctions. From δE, we determine the Fermi velocity of the bilayer graphene, which is found to increase with gate voltage. Simultaneously, we show the carrier density dependence of δE, which is attributed to the quadratic dispersion of bilayer graphene. This is in contrast to single layer graphene Josephson junctions, where δE and the Fermi velocity are independent of the carrier density. The carrier density dependence in BGJJs allows for additional tuning parameters in graphene-based Josephson junction devices.

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75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITYAndreev LevelsBilayer GrapheneElectrical propertiesEnergyFermi VelocityGrapheneJosephson JunctionsOxidesSuperconductivityTwo dimensional materialsVesicles

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Sharma, Amis [Texas A&M University, College Station, TX (United States)] (ORCID:0000000277283753), Chen, Chun-Chia [Duke University, Durham, NC (United States)], McCourt, Jordan [Duke University, Durham, NC (United States)], Kim, Mingi [Purdue University, West Lafayette, IN (United States)], Watanabe, Kenji [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000337018119), Taniguchi, Takashi [National Institute for Materials Science (NIMS), Tsukuba (Japan)] (ORCID:0000000214673105), Rokhinson, Leonid [Purdue University, West Lafayette, IN (United States)], Finkelstein, Gleb [Duke University, Durham, NC (United States)], Borzenets, Ivan [Texas A&M University, College Station, TX (United States)] (ORCID:0000000215778312). 2025-03-19. Fermi Velocity Dependent Critical Current in Ballistic Bilayer Graphene Josephson Junctions. https://doi.org/10.1021/acsnanoscienceau.4c00080

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