Superconductivity in Twisted Trilayer Graphene

Strongly correlated physics has been a central topic in condensed matter physics for decades, as it gives rise to a wide range of emergent phenomena such as unconventional superconductivity, quantum spin liquids and fractionalized excitations. In recent years, twisted van der Waals materials have emerged as an ideal platform for exploring strong correlated physics. These moire systems provide a highly tunable environment in which strong correlations can coexist and interplay with topology, enabling the discovery of novel quantum phases. One of the most fascinating manifestations of such quantum matter is unconventional superconductivity in twisted graphene systems. Since its discovery in 2018, extensive efforts have been made to understand the origin of superconductivity and the nature of the associated order parameters. While significant progress has been achieved such as evidence for nodal order parameters, a complete and unified understanding of the superconducting mechanism remains elusive.

In this thesis, we focus on the investigation of superconductivity in twisted trilayer graphene systems. First, we study magic-angle twisted trilayer graphene (MATTG) and demonstrate the existence of double-dome superconductivity within a narrow displacement field window. Second, we study mirror-symmetry-broken twisted trilayer graphene and demonstrate the existence of a supermoire lattice from the interference of two moire lattice, along with the presence of superconductivity and strong correlation effects on the supermoire length scale. Our results offer new insights into the nature of superconductivity in moire graphene systems and suggest new pathways for designing and discovering novel quantum phases.