Sub-system resolved physics in moiré heterostructures

Emergent phenomena in moiré van der Waals structures are commonly ascribed to the collective moiré spectrum, characterizing the entire system, not the individual layers. Nevertheless, recent experiments are now able to identify correlated features resolved at the subsystem level. In this study, we theoretically show that some correlated phenomena in moiré systems can be attributed to individual subsystems. Using a combination of large-scale first-principles DFT calculations and effective models, we demonstrate that the correlated features in general moiré systems can be attributed to subsystems. This general idea is particularly demonstrated by analysing correlated features observed in twisted monolayer-bilayer and twisted bilayer-bilayer systems and we show that they stem from the bilayer subsystem. Furthermore, we present a series of toy models to provide physical insights into the asymmetric nature of the correlated regions in twisted monolayer-bilayer compared to that in twisted bilayer-bilayer graphene.