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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.

権利情報:

• Creative Commons BY Attribution 4.0 International
  

キーワード: twisted trilayer graphene (TTG)
, orbital magnetism, superconductivity


刊行年月日: 2025-12-24

出版者: American Chemical Society (ACS)

掲載誌:

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

研究助成金:

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

原稿種別: 出版者版 (Version of record)

MDR DOI:

公開URL: https://doi.org/10.1021/acsami.5c15822

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更新時刻: 2026-02-17 12:30:53 +0900

MDRでの公開時刻: 2026-02-17 09:10:58 +0900