Moiré Effects Approaching and Within the Bulk Graphitic Limit

Moiré quantum materials have recently emerged as highly tunable platforms for the study of strongly correlated and topological states of matter. Although first realized in twisted bilayer graphene, a wealth of new physics has recently been discovered in other twisted multilayer graphene structures. Here, I will discuss an array of moiré-driven effects that emerge in the family of twisted <i>M</i>+<i>N</i> graphene multilayers, defined as structures created by stacking and slightly rotating <i>M</i>-layer and <i>N</i>-layer Bernal-stacked graphene sheets. We observe spontaneous isospin symmetry breaking and signatures of non-trivial topology in a wide variety of these structures (e.g., t1+2, t2+2, t1+3, t2+3, etc). Although the precise details vary across platforms, we find an apparent universality of the overall correlated phase diagram resulting from the similar flat moiré bands of these different structures. We further discover entirely new types of moiré reconstruction effects upon entering the bulk graphitic limit, in which the total number of graphene layers exceeds ~10 (e.g., t1+10). The surface moiré potential can strongly modify the transport properties of the entire bulk graphite sheet, indicating the dominant role of the band hybridization at the moiré interface. Our work points toward a general understanding of strongly correlated and topological states, as well as moiré band reconstruction, in multilayer graphitic systems with a single rotated interface.