Strong Proximity Josephson Coupling in Vertically Stacked NbSe2-Graphene-NbSe2 van der Waals Junctions

Minsoo Kim, Geon Hyoung Park, Jongyun Lee, Jae Hyeong Lee, Jinho Park, Hyunwoo Lee, Gil Ho Lee, Hu Jong Lee

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    Abstract

    A layered two-dimensional superconducting material 2H-NbSe2 is used to build a van der Waals heterostructure, where a proximity-coupled superconducting order can be induced in the interfacing materials. Vertically stacked NbSe2-graphene-NbSe2 is fabricated using van der Waals interlayer coupling, producing defect-free contacts with a high interfacial transparency. The atomically thin graphene layer allows the formation of a highly coherent proximity Josephson coupling between the two NbSe2 flakes. The temperature dependence of the junction critical current (Ic) reveals short and ballistic Josephson coupling characteristics that agree with theoretical prediction. The strong Josephson coupling is confirmed by a large junction critical current density of 1.6 × 104 A/cm2, multiple Andreev reflections in the subgap structure of the differential conductance, and a magnetic-field modulation of Ic. This is the first demonstration of strongly proximity-coupled Josephson junctions with extremely clean interfaces in a dry-transfer-stacked van der Waals heterostructure.

    Original languageEnglish
    Pages (from-to)6125-6130
    Number of pages6
    JournalNano Letters
    Volume17
    Issue number10
    Early online date27 Sept 2017
    DOIs
    Publication statusPublished - 11 Oct 2017

    Keywords

    • Graphene
    • heterostructure
    • Josephson junction
    • NbSe
    • two-dimensional materials

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