Competing Orbital Magnetism and Superconductivity in In-Situ Josephson Junctions of Alternating Twisted Trilayer Graphene

The coexistence of superconductivity and magnetism within a single platform has been a long-standing goal in condensed matter physics. Van der Waals-based moiré superlattices offer a unique avenue for realizing broken symmetry states within a single device. In alternating twisted trilayer graphene (TTG), robust superconductivity—tunable by displacement field—emerges at the magic angle (1.57°) and reappears at 1.3° but is suppressed at intermediate twist angles. In this study, we explore the intermediate angle regime around 1.40°, where superconductivity is suppressed, and report evidence of orbital magnetism. Unlike superconductivity, which is strong at higher moiré fillings, orbital magnetism is most prominent near the charge neutrality point (CNP), diminishing at larger fillings. Similarly, higher displacement fields favor superconductivity, whereas lower fields enhance orbital magnetism. These complementary trends suggest a competitive relationship between the two states. Using gate-defined Josephson junctions we detected orbital magnetism via an asymmetric Fraunhofer pattern, with an ordering temperature around 650 mK—below the superconducting transition temperature (~1.3K). This lower energy scale implies that the orbital magnetism observed here, likely driven by valley polarization, differs from the anomalous Hall effect seen at integer fillings in twisted graphene systems.