Affiliation
National University of Singapore
Title
Topological Flat Bands in Graphene Super-moiré Lattices
Abstract
Moiré-pattern based potentials have emerged as a driving force behind the exploration of exotic physics in various condensed matter systems. While these potentials have induced correlated phenomena in almost all commonly studied 2D materials, monolayer graphene has remained an exception. In this letter, we present a theoretical study demonstrating that a single layer of graphene, when placed between two bulk boron nitride crystal substrates with the right twist angles that create a commensurate super-moiré potential, can support a topological ultra-flat band. This configuration, which can be easily fabricated using existing experimental capabilities [1], offers one of the simplest platforms for the realization of topological flat bands. Notably, the flat band originates from the second hole band and exhibits robustness against Hartree-Fock corrections. As a result, we anticipate that this system will provide a fertile ground for the investigation of strongly correlated physics. Furthermore, our continuum model demonstrates that similar topological flat bands also arise in graphene bilayers and trilayers when subjected to similar sandwiching by boron nitride substrates. These findings unveil new possibilities for the engineering of moiré-induced topological flat bands in graphene-based systems, opening up avenues for further exploration and potential applications in condensed matter physics.
[1] Junxiong Hu, Junyou Tan, Mohammed M Al Ezzi, Udvas Chattopadhyay, Jian Gou, Yuntian Zheng, Zihao Wang, Jiayu Chen, Reshmi Thottathil, Jiangbo Luo, et al. “Controlled alignment of supermoiré lattice in double-aligned graphene heterostructures”. arXiv:2301.12124, 2023