Investigating the twist-angle dependence of Bernal bilayer-trilayer graphene

Recent studies have established twisted Bernal bilayer-trilayer graphene as a rich platform for investigating correlation-driven topological states formed within a moiré superlattice. A particular highlight is the discovery of a highly tunable integer quantum anomalous Hall state arising at band filling ν = 1/4, along with additional Chern insulators associated with ν = 1/3, 1/2, 2/3, and 3/2 that form in modest magnetic fields. The appearance of these states at commensurate fractional fillings of the moiré bands strongly suggests that they are formed by spontaneously breaking the discrete translational symmetry of the superlattice. Such states thus correspond to moiré-driven topological electronic crystals, featuring enlarged unit cells. However, the dependence of these states on the twist angle between the bilayer and trilayer graphene constituents is currently unknown. In this talk, I will present transport measurements helping to fill in this gap by studying twisted bilayer-trilayer graphene across a range of twist angles from < 1° to 1.7°. These measurements reveal a rich set of symmetry-broken phases that depend sensitively on twist angle, motivating the possibility of uncovering intriguing new topological phases of matter in this platform.