Realization of rhombohedral-stacked trilayer graphene by moiré engineering

Rhombohedral (ABC) stacked multilayer graphene hosts low-energy flat bands, which have proven to be an ideal platform toward achieving interaction-driven physics including superconductivity and ferromagnetism. However, of the two common multilayer graphene configurations, ABC stacked graphene is less energy favorable than the Bernal (ABA), as a result, experimental realization of large-area ABC stacked graphene is still big challenge up till now. Here we report a facile method to controllably realize a sub-micrometer-scale ABC stacked trilayer graphene (ABC-TG). By rotating graphene monolayer relative to a bilayer with a tiny angle, we observe a large-area and periodic ABC-TG region after atomic reconstruction. Our experiment indicates that the obtained ABC-TG region is rather stable under thermal annealing and pulse voltages. Using scanning tunneling microcopy (STM), we demonstrate that the flat bands of the ABC-TG region exhibit a pronounced size-dependent characteristic when the size of ABC-TG is smaller than about 100 nm, whereas, the bandwidth of the flat bands becomes a constant when the size is larger than about 100 nm, implying a minimal size for exploring emergent correlated physics in the ABC stacked graphene.