Symmetry-broken Josephson junctions and superconducting diodes in magic-angle twisted bilayer graphene

J. Díez-Mérida; A. Díez-Carlón; S. Y. Yang; Y. M. Xie; X. J. Gao; Jorden Senior; K. Watanabe; T. Taniguchi; X. Lu; A. P. Higginbotham; K. T. Law; Dmitri K. Efetov

doi:10.1038/s41467-023-38005-7

Symmetry-broken Josephson junctions and superconducting diodes in magic-angle twisted bilayer graphene

J. Díez-Mérida, A. Díez-Carlón, S. Y. Yang, Y. M. Xie, X. J. Gao, Jorden Senior, K. Watanabe, T. Taniguchi, X. Lu, A. P. Higginbotham, K. T. Law, Dmitri K. Efetov^*

^*Corresponding author for this work

Not published at VTT

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

90 Citations (Scopus)

Abstract

The coexistence of gate-tunable superconducting, magnetic and topological orders in magic-angle twisted bilayer graphene provides opportunities for the creation of hybrid Josephson junctions. Here we report the fabrication of gate-defined symmetry-broken Josephson junctions in magic-angle twisted bilayer graphene, where the weak link is gate-tuned close to the correlated insulator state with a moiré filling factor of υ = −2. We observe a phase-shifted and asymmetric Fraunhofer pattern with a pronounced magnetic hysteresis. Our theoretical calculations of the junction weak link—with valley polarization and orbital magnetization—explain most of these unconventional features. The effects persist up to the critical temperature of 3.5 K, with magnetic hysteresis observed below 800 mK. We show how the combination of magnetization and its current-induced magnetization switching allows us to realise a programmable zero-field superconducting diode. Our results represent a major advance towards the creation of future superconducting quantum electronic devices.

Original language	English
Article number	2396
Journal	Nature Communications
Volume	14
Issue number	1
DOIs	https://doi.org/10.1038/s41467-023-38005-7
Publication status	Published - 26 Apr 2023
MoE publication type	A1 Journal article-refereed

Funding

We are grateful for the fruitful discussions with Allan MacDonald and Andrei Bernevig. D.K.E. acknowledges support from the Ministry of Economy and Competitiveness of Spain through the “Severo Ochoa” program for Centers of Excellence in R&D (SE5-0522), Fundació Privada Cellex, Fundació Privada Mir-Puig, the Generalitat de Catalunya through the CERCA program, funding from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no. 852927)” and the La Caixa Foundation. K.T.L. acknowledges the support of the Ministry of Science and Technology of China and the HKRGC through grants MOST20SC04, C6025-19G, 16310219, 16309718, and 16310520. J.D.M. acknowledges support from the INPhINIT ‘la Caixa’ Foundation (ID 100010434) fellowship program (LCF/BQ/DI19/11730021). Y.M.X. acknowledges the support of HKRGC through Grant No. PDFS2223-6S01.

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Díez-Mérida, J., Díez-Carlón, A., Yang, S. Y., Xie, Y. M., Gao, X. J., Senior, J., Watanabe, K., Taniguchi, T., Lu, X., Higginbotham, A. P., Law, K. T., & Efetov, D. K. (2023). Symmetry-broken Josephson junctions and superconducting diodes in magic-angle twisted bilayer graphene. Nature Communications, 14(1), Article 2396. https://doi.org/10.1038/s41467-023-38005-7

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Symmetry-broken Josephson junctions and superconducting diodes in magic-angle twisted bilayer graphene

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