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The coexistence of superconductivity and magnetism within a single material system represents a long-standing goal in condensed matter physics. Van der Waals-based moiré superlattices provide an exceptional platform for exploring competing and coexisting broken symmetry states. Alternating twisted trilayer graphene (TTG) exhibits robust superconductivity at the magic angle of 1.57° and 1.3°, with suppression at intermediate twist angles. In this study, we investigate the intermediate regime and uncover evidence of orbital magnetism. As previously reported, superconductivity is suppressed near the charge neutrality point (CNP) and emerges at larger moiré fillings. Conversely, we find orbital magnetism most substantial near the CNP, diminishing as superconductivity develops. This complementary behavior is similarly observed in the displacement field phase space, highlighting a competitive interplay between the two phases. Utilizing gate-defined Josephson junctions, we probe orbital magnetism by electrostatically tuning the weak links into the magnetic phase, revealing an asymmetric Fraunhofer interference pattern. The estimated orbital ferromagnetic ordering temperature is approximately half the superconducting critical temperature, coinciding with the onset of Fraunhofer asymmetry. Our findings suggest that the observed orbital magnetism is driven by valley polarization and is distinct from the anomalous Hall effect reported at integer fillings in twisted graphene systems. These results offer insights into the interplay between superconductivity and magnetism in moiré superlattices.

Rights:

• Creative Commons BY Attribution 4.0 International
  

Keyword: twisted trilayer graphene (TTG)
, orbital magnetism, superconductivity


Date published: 2025-12-24

Publisher: American Chemical Society (ACS)

Journal:

• ACS Applied Materials & Interfaces (ISSN: 19448244) vol. 17 issue. 51 p. 69784-69794

Funding:

• Bundesministerium für Bildung und Forschung
• Minerva Foundation
• H2020 European Research Council 101163917
• Gerald Schwartz and Heather Reisman Foundation

Manuscript type: Publisher's version (Version of record)

MDR DOI:

First published URL: https://doi.org/10.1021/acsami.5c15822

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Updated at: 2026-02-17 12:30:53 +0900

Published on MDR: 2026-02-17 09:10:58 +0900