Novel electrical properties of moiré graphene systems

In this review, we discuss the electronic structures, topological properties, correlated states, nonlinear optical responses, as well phonon and electron-phonon coupling effects of moiré graphene superlattices. First, illustrate that topologically non-trivial flat bands orbital magnetism are ubiquitous in various twisted systems. particular, magic-angle bilayer can be explained from a zeroth pseudo-Landau-level picture, which naturally explain experimentally observed quantum anomalous Hall effect some other states. These nontrivial may lead to nearly quantized piezoelectric response, used directly probe valley Chern numbers these A simple general chiral decomposition rule is reviewed discussed, predict low-energy band dispersions generic multilayer system alternating system. This review further discusses interaction TBG such insulator density wave cascade transitions, nematic proposes measurement an experimental distinguish different “featureless” The properties also briefly reviewed. novel physics emerging band-aligned graphene-insulator heterostructres discussed review. end, make summary outlook about physical superlattices based on two-dimensional materials.