Emergent Quantum Phenomena in Magic-Angle Twisted Graphene Superlattices

Abstract

Strongly correlated electron systems have attracted considerable interest due to their ability to host a wealth of emergent quantum phenomena. Recently, moiré engineering, also known as twistronics, has emerged as a new approach for creating twodimensional correlated materials. In this thesis, I designed and studied novel moiré quantum matter based on twisted graphene superlattices. Starting with the discovery of magic-angle twisted trilayer graphene, I established a family of highly tunable materials that display unconventional correlated and superconducting phases. The superconductivity observed in this magic family demonstrates strong coupling and significant violation of the Pauli limit. By integrating transport and thermodynamic measurements, I uncovered the electronic structures behind the correlated phases and the spontaneous breaking of flavor symmetry. Additionally, by merging correlation and topology in magic-angle graphene, a fractional Chern insulator phase was realized at low magnetic fields. These results provide a robust and versatile platform for investigating emergent phenomena in two dimensions.