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

M. Ben Shalom; M. J. Zhu; V. I. Fal'ko; A. Mishchenko; A. V. Kretinin; K. S. Novoselov; C. R. Woods; K. Watanabe; T. Taniguchi; A. K. Geim; J. R. Prance

doi:10.1038/nphys3592

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

M. Ben Shalom, M. J. Zhu, V. I. Fal'ko^*, A. Mishchenko, A. V. Kretinin, K. S. Novoselov, C. R. Woods, K. Watanabe, T. Taniguchi, A. K. Geim, J. R. Prance

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

Abstract

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.

Original language	English
Pages (from-to)	318-322
Number of pages	5
Journal	Nature Physics
Volume	12
Issue number	4
DOIs	https://doi.org/10.1038/nphys3592
Publication status	Published - 1 Apr 2016

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National Graphene Institute

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title = "Quantum oscillations of the critical current and high-field superconducting proximity in ballistic graphene",

abstract = "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-P{\'e}rot 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.",

author = "{Ben Shalom}, M. and Zhu, {M. J.} and Fal'ko, {V. I.} and A. Mishchenko and Kretinin, {A. V.} and Novoselov, {K. S.} and Woods, {C. R.} and K. Watanabe and T. Taniguchi and Geim, {A. K.} and Prance, {J. R.}",

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doi = "10.1038/nphys3592",

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AU - Ben Shalom, M.

AU - Zhu, M. J.

AU - Fal'ko, V. I.

AU - Mishchenko, A.

AU - Kretinin, A. V.

AU - Novoselov, K. S.

AU - Woods, C. R.

AU - Watanabe, K.

AU - Taniguchi, T.

AU - Geim, A. K.

AU - Prance, J. R.

PY - 2016/4/1

Y1 - 2016/4/1

N2 - 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.

AB - 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.

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SP - 318

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JO - Nature Physics

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

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