Tunable quantum interferometer for correlated moiré electrons

Magic-angle twisted bilayer graphene can host a variety of gate-tunable correlated states – including superconducting and correlated insulator states. Recently, junction-based superconducting moiré devices have been introduced, enabling the study of the charge, spin and orbital nature of superconduc...

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Published in:Nature communications 2024-01, Vol.15 (1), p.390-390, Article 390
Main Authors: Iwakiri, Shuichi, Mestre-Torà, Alexandra, Portolés, Elías, Visscher, Marieke, Perego, Marta, Zheng, Giulia, Taniguchi, Takashi, Watanabe, Kenji, Sigrist, Manfred, Ihn, Thomas, Ensslin, Klaus
Format: Article
Language:English
Subjects:
639/766/1130/1064
639/925/918/1052
Bilayers
Coherence length
Correlation
Electrons
Graphene
Humanities and Social Sciences
Magnetic fields
multidisciplinary
Oscillations
Parks
Parks & recreation areas
Phase diagrams
Science
Science (multidisciplinary)
Superconductivity
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Summary:Magic-angle twisted bilayer graphene can host a variety of gate-tunable correlated states – including superconducting and correlated insulator states. Recently, junction-based superconducting moiré devices have been introduced, enabling the study of the charge, spin and orbital nature of superconductivity, as well as the coherence of moiré electrons in magic-angle twisted bilayer graphene. Complementary fundamental coherence effects—in particular, the Little–Parks effect in a superconducting ring and the Aharonov–Bohm effect in a normally conducting ring – have not yet been reported in moiré devices. Here, we observe both phenomena in a single gate-defined ring device, where we can embed a superconducting or normally conducting ring in a correlated or band insulator. The Little–Parks effect is seen in the superconducting phase diagram as a function of density and magnetic field, confirming the effective charge of 2 e . We also find that the coherence length of conducting moiré electrons exceeds several microns at 50 mK. In addition, we identify a regime characterized by h / e -periodic oscillations but with superconductor-like nonlinear transport. Gate-defined superconducting moiré devices offer high tunability for probing the nature of superconducting and correlated insulating states. Here, the authors report the Little–Parks and Aharonov–Bohm effects in a single gate-defined magic-angle twisted bilayer graphene device.
ISSN:2041-1723
2041-1723
DOI:10.1038/s41467-023-44671-4