Quantum oscillations of the critical current and high-field superconducting proximity in ballistic graphene

Ben Shalom, M. and Zhu, M. J. and Fal'ko, V. I. and Mishchenko, A. and Kretinin, A. V. and Novoselov, K. S. and Woods, C. R. and Watanabe, K. and Taniguchi, T. and Geim, A. K. and Prance, Jonathan Robert (2016) Quantum oscillations of the critical current and high-field superconducting proximity in ballistic graphene. Nature physics, 12 (4). pp. 318-322. ISSN 1745-2473

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Graphene-based Josephson junctions provide a novel platform for studying the proximity effect due to graphene’s unique electronic spectrum and the possibility to tune junction properties by gate voltage. Here we describe graphene junctions with a mean free path of several micrometres, low contact resistance and large supercurrents. Such devices exhibit pronounced Fabry–Pérot oscillations not only in the normal-state resistance but also in the critical current. The proximity effect is mostly suppressed in magnetic fields below 10 mT, showing the conventional Fraunhofer pattern. Unexpectedly, some proximity survives even in fields higher than 1 T. Superconducting states randomly appear and disappear as a function of field and carrier concentration, and each of them exhibits a supercurrent carrying capacity close to the universal quantum limit. We attribute the high-field Josephson effect to mesoscopic Andreev states that persist near graphene edges. Our work reveals new proximity regimes that can be controlled by quantum confinement and cyclotron motion.

Item Type: Journal Article
Journal or Publication Title: Nature physics
Uncontrolled Keywords: /dk/atira/pure/subjectarea/asjc/3100
Departments: Faculty of Science and Technology > Physics
ID Code: 78880
Deposited By: ep_importer_pure
Deposited On: 01 Apr 2016 07:44
Refereed?: Yes
Published?: Published
Last Modified: 19 Sep 2019 00:44
URI: https://eprints.lancs.ac.uk/id/eprint/78880

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