Tunable Chern Insulators in Moiré-Distant and Moiré-Proximal Rhombohedral Multilayer Graphene

In this talk, we report on the electrical transport properties of rhombohedral multilayer graphene/hexagonal boron nitride (RMG/hBN) moiré superlattices. By fabricating a controlled pair of devices with opposite hBN alignment orientations, we find that the integer and fractional quantum anomalous Hall effects (IQAHE and FQAHE) in the moiré-distant region are unaffected by the alignment orientation. In contrast, the moiré-proximal region exhibits a pronounced dependence on the hBN orientation: only one alignment configuration shows an anomalous Hall effect near ν = 1, which evolves into topological Chern insulators under a small magnetic field. Moreover, the Chern number can be tuned by both magnetic and displacement electric fields. These results provide important insights into understanding the FQAHE in the moiré-distant region.