Planar graphene Josephson coupling via van der Waals superconducting contacts

Jongyun Lee, Minsoo Kim, Kenji Watanabe, Takashi Taniguchi, Gil Ho Lee, Hu Jong Lee

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    Abstract

    We report on the fabrication and transport characteristics of van der Waals (vdW)-contacted planar Josephson junctions. In a device, two pieces of cleaved 2H-NbSe 2 superconducting flakes and a monolayer graphene sheet serve as the superconducting electrodes and the normal-conducting spacer, respectively. A stack of NbSe 2 −graphene−hexagonal-boron-nitride (hBN) heterostructure with clean and flat interfaces was prepared by a dry transfer technique. The outermost hBN layer protected the NbSe 2 −graphene−NbSe 2 Josephson junction from chemical contamination during the fabrication processes. The Josephson coupling was confirmed by a periodic modulation of the junction critical current I c in a perpendicular magnetic field. The temperature dependence of I c showed long and diffusive Josephson coupling characteristics. The temperature dependence of the superconducting gap, obtained from the multiple Andreev reflection features, followed the Bardeen−Cooper−Schrieffer (BCS) prediction.

    Original languageEnglish
    Pages (from-to)251-255
    Number of pages5
    JournalCurrent Applied Physics
    Volume19
    Issue number3
    Early online date3 Jul 2018
    DOIs
    Publication statusPublished - 1 Mar 2019

    Keywords

    • Dry transfer
    • Graphene
    • NbSe
    • Proximity Josephson junction
    • Van der Waals stacking

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