Moiré modification of graphitic thin films

Moiré patterns formed by stacking atomically thin van der Waals crystals can give rise to dramatic new physical properties, in select cases generating flat bands that host a variety of strongly correlated and topological states of matter. I will focus on the evolution of moiré effects in graphitic structures as their thickness varies from just a few layers into the bulk limit. In particular, I will overview the properties of a family of Bernal-stacked graphene structures that feature a single twisted interface residing within the crystal. In the atomically thin limit of less than seven total graphene layers, we observe striking commonalities in the emergent correlated and topological states arising from the moiré flat bands across many different layer-number constructions. Theoretical modeling reveals that this effect originates from the localization of low-energy states to the twisted interface within the structure. We further find that moiré band formation persists even in bulk graphite structures with a single rotational fault. When we expose twisted graphene-graphite samples to a large magnetic field, standing waves form along the c-axis of the crystal and hybridize the 2D moiré states with the bulk states of the 3D graphite thin film. Our results demonstrate that creating a small twist within graphite can modify the properties of the entire bulk crystal.