Imaging Magic-Angle Twisted Bilayer Graphene: Part III

Magic-angle twisted bilayer graphene (MATBG) hosts many correlated ground states, including correlated insulating, superconducting, and magnetic phases [1]. Theoretical studies have predicted an intense energetic competition among several candidate ground states in MATBG, but it appears to be very difficult to differentiate among them without spatially resolved experiments [2, 3]. Fortunately, scanning tunneling microscopy (STM) has the capability to access key microscopic observables predicted by theory that are crucial for understanding the origin of these phases. In this final talk in a series of three presentations, I will discuss how we combine STM imaging experiments with a unified symmetry-based analysis framework to extract quantitative information about gapped phases in MATBG. In large-scale imaging experiments, we identify universal real-space features that are shared across devices, and identify more subtle features that are highly sample-dependent. This approach allows us to directly compare candidate ground states to our experimental observations, which we use to distinguish the nature of the insulating phases near v = +-2 in MATBG, ruling out leading theoretical contenders for these states on the basis of symmetry.