Prof. Zheng Vitto Han, Institute of Opto-Electronics, Shanxi University, Taiyuan, China
In this talk, we will introduce a model system: synergetic interplay between two layers of 2D interacting interacted electronic system, and the emerging phenomena.
Taking the van der Waal hybrid system of graphene/CrOCl for example, our theoretical considerations suggest that, due to e-e interactions, the electrons filled (charge transferred from graphene with the help of vertical electrical field) in the surface state (mainly in the Cr-3d orbital in CrOCl, which is about 0.7 nm below graphene) of CrOCl can spontaneously form a long wavelength order, i.e., it undergoes a Wigner crystallization. Such a long wavelength charge order can act as a quantum superlattice, which exerts a moiré-like super potential to the graphene placed on top of it, and further leads to a series of exotic interaction-driven phenomena, including unusually robust quantum Hall phase [1], and exciton-enhanced correlated insulator [2].
Our findings suggest that the paradigm of charge transfer can play key roles in the engineering of quantum electronic states, when the e-e interactions are taking effects. And, according to theory, such a quantum superlattice may be a universal phenomenon in many layered materials [3], and enriched physical phenomena are yet to be discovered.