Exotic quantum phenomena in twisted bilayer graphene

Bilayer graphene twisted at the angle of about 1.1°, better known as the magic angle, hosts ultra-flat moiré superlattice bands that are a source of highly-tunable, unconventional quantum phenomena. Such phenomena, like superconductivity, correlated Mott-like insulating states and orbital ferromagnetism stem from strong correlations that defy classical descriptions. The inadequacy of classical frameworks and the lack of theoretical understanding of the recently observed emergent phenomena in magic angle graphene highlights the need to revisit the underlying physics of this system and establishing a clearer connection with the observed behaviour. This article reviews the physics behind twisted bilayer graphene, focusing primarily on moiré physics and the importance of electronic (flat) band structure. It also provides a brief overview of the emerging phenomena such as correlated insulating states, superconductivity and orbital ferromagnetism. Finally, the most recent advances in tuning the electronic phases and controlling the interaction-driven states are presented.