Transparent Josephson junctions in higher-order topological insulator WTe2 via Pd diffusion

Martin Endres; Artem Kononov; Michael Stiefel; Marcus Wyss; Hasitha Suriya Arachchige; Jiaqiang Yan; David Mandrus; Kenji Watanabe; Takashi Taniguchi; Christian Schönenberger

doi:10.1103/PhysRevMaterials.6.L081201

Transparent Josephson junctions in higher-order topological insulator WTe2 via Pd diffusion

Martin Endres
, Artem Kononov
, Michael Stiefel
, Marcus Wyss
, Hasitha Suriya Arachchige
, Jiaqiang Yan
, David Mandrus
, Kenji Watanabe
, Takashi Taniguchi
, Christian Schönenberger

Correlated Electron Materials

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

10 Scopus citations

Abstract

Highly transparent superconducting contacts to a topological insulator (TI) remain a persistent challenge on the route to engineer topological superconductivity. Recently, the higher-order TI WTe2 was shown to turn superconducting when placed on palladium (Pd) bottom contacts, demonstrating a promising material system in pursuing this goal. Here, we report the diffusion of Pd into WTe2 and the formation of superconducting PdTex as the origin of observed superconductivity. We find an atomically sharp interface in the direction vertical to the van der Waals layers between the diffusion crystal and its host crystal, forming state-of-the-art superconducting contacts to a TI. The diffusion is discovered to be nonuniform along the width of the WTe2 crystal, with a greater extent along the edges compared to the bulk. The potential of this contacting method is highlighted in transport measurements on Josephson junctions by employing external superconducting leads.

Original language	English
Article number	L081201
Journal	Physical Review Materials
Volume	6
Issue number	8
DOIs	https://doi.org/10.1103/PhysRevMaterials.6.L081201
State	Published - Aug 2022

Funding

Acknowledgments. We thank Paritosh Karnatak for fruitful discussions. This project has received funding from the European Research Council (ERC) under the European Unions Horizon 2020 research and innovation programme, Grant No. 787414 TopSupra; from the Swiss National Science Foundation through the National Centre of Competence in Research Quantum Science and Technology (QSIT); and from the Swiss Nanoscience Institute (SNI). A.K. was supported by the Georg H. Endress Foundation. D.M. and J.Y. acknowledge support from the U.S. Department of Energy (U.S. DOE), Office of Science, Basic Energy Sciences (BES), Materials Sciences and Engineering Division. H.S.A. was supported by the Gordon and Betty Moore Foundation's EPiQS Initiative through Grant No. GBMF9069 and the Shull Wollan Center Graduate Research Fellowship. D.M. acknowledges support from the Gordon and Betty Moore Foundation's EPiQS Initiative, Grant No. GBMF9069. K.W. and T.T. acknowledge support from the Elemental Strategy Initiative conducted by MEXT, Japan, and the CREST (Grant No. JPMJCR15F3), JST.

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10.1103/PhysRevMaterials.6.L081201

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title = "Transparent Josephson junctions in higher-order topological insulator WTe2 via Pd diffusion",

abstract = "Highly transparent superconducting contacts to a topological insulator (TI) remain a persistent challenge on the route to engineer topological superconductivity. Recently, the higher-order TI WTe2 was shown to turn superconducting when placed on palladium (Pd) bottom contacts, demonstrating a promising material system in pursuing this goal. Here, we report the diffusion of Pd into WTe2 and the formation of superconducting PdTex as the origin of observed superconductivity. We find an atomically sharp interface in the direction vertical to the van der Waals layers between the diffusion crystal and its host crystal, forming state-of-the-art superconducting contacts to a TI. The diffusion is discovered to be nonuniform along the width of the WTe2 crystal, with a greater extent along the edges compared to the bulk. The potential of this contacting method is highlighted in transport measurements on Josephson junctions by employing external superconducting leads.",

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AU - Endres, Martin

AU - Kononov, Artem

AU - Stiefel, Michael

AU - Wyss, Marcus

AU - Arachchige, Hasitha Suriya

AU - Yan, Jiaqiang

AU - Mandrus, David

AU - Watanabe, Kenji

AU - Taniguchi, Takashi

AU - Schönenberger, Christian

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AB - Highly transparent superconducting contacts to a topological insulator (TI) remain a persistent challenge on the route to engineer topological superconductivity. Recently, the higher-order TI WTe2 was shown to turn superconducting when placed on palladium (Pd) bottom contacts, demonstrating a promising material system in pursuing this goal. Here, we report the diffusion of Pd into WTe2 and the formation of superconducting PdTex as the origin of observed superconductivity. We find an atomically sharp interface in the direction vertical to the van der Waals layers between the diffusion crystal and its host crystal, forming state-of-the-art superconducting contacts to a TI. The diffusion is discovered to be nonuniform along the width of the WTe2 crystal, with a greater extent along the edges compared to the bulk. The potential of this contacting method is highlighted in transport measurements on Josephson junctions by employing external superconducting leads.

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Transparent Josephson junctions in higher-order topological insulator WTe2 via Pd diffusion

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