Gate-Tunable Orbital Magnetism and Competing Superconductivity in Twisted Trilayer Graphene Josephson Junctions

Twisted trilayer graphene (TTG) provides a tunable moiré platform to study correlated phases emerging from flat-band physics. Here, we investigate the interplay between superconductivity and spontaneous orbital magnetism (OM) in alternating TTG devices with intermediate twist angles (1.38-1.44°). Using electrostatically defined Josephson junctions, we demonstrate that OM, stabilized near the charge neutrality point (CNP), competes with gate-induced superconductivity. The OM phase is characterized by sharp jumps in Hall resistance, current-induced bistability, and a Curie-Bloch temperature dependence, indicating broken time-reversal symmetry. Additionally, nonreciprocal Josephson transport─manifested as asymmetric Fraunhofer patterns and a superconducting diode effect─provides independent evidence of an orbital magnetic state confined to the weak link. The observed critical temperature hierarchy, where superconductivity dominates over OM at higher carrier densities and displacement fields, reveals a tunable competition between two broken-symmetry ground states. Our findings establish alternating TTG Josephson devices as a minimal and versatile platform to probe the coexistence of magnetism and superconductivity in engineered moiré systems.