Building 3D superconductor-based Josephson junctions using a via transfer approach

Cequn Li; Le Yi; Kalana D. Halanayake; Jessica L. Thompson; Yingdong Guan; Kenji Watanabe; Takashi Taniguchi; Zhiqiang Mao; Danielle Reifsnyder Hickey; Morteza Kayyalha; Jun Zhu

doi:10.1021/acsnanoscienceau.5c00180

arXiv · 2511.17386

Building 3D superconductor-based Josephson junctions using a via transfer approach

Cequn Li·Le Yi·Kalana D. Halanayake·Jessica L. Thompson·Yingdong Guan·Kenji Watanabe·Takashi Taniguchi·Zhiqiang Mao·Danielle Reifsnyder Hickey·Morteza Kayyalha·Jun Zhu

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Abstract

The coupling of superconductivity to unconventional materials may lead to novel quantum states and potential applications. Controlling the quality of the superconductor-normal metal interface is of crucial importance to the understanding and engineering of the superconducting proximity effect. In many cases, conventional lithography-based deposition methods introduce undesirable effects. Using the concept of via contact and dry transfer, we have constructed smooth, van der Waals-like contact between 3D superconducting NbN/Pd and graphene with low contact resistance of approximately 130 $\Omega \cdot \mu m$. Gate-tunable supercurrent, Fraunhofer pattern, and Andreev reflections are observed, the properties of which can be understood using an induced superconducting gap $\Delta$' in this planar contact geometry. We discuss potential mechanisms impacting the magnitude of $\Delta$' and suggest ways of further increasing the proximity coupling. This gentle, lithography-free contacting method can be applied to air- and damage-sensitive surfaces to engineer novel superconducting heterostructures.

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cond-mat.mes-hall cond-mat.mtrl-sci cond-mat.supr-con

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Cequn Li, Le Yi, Kalana D. Halanayake, Jessica L. Thompson, Yingdong Guan, Kenji Watanabe, Takashi Taniguchi, Zhiqiang Mao, Danielle Reifsnyder Hickey, Morteza Kayyalha, Jun Zhu. 2025-11-21. Building 3D superconductor-based Josephson junctions using a via transfer approach. https://doi.org/10.1021/acsnanoscienceau.5c00180

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