Simpler van der Waals Heterostructure-Twisted Bilayer Graphene

Twisted bilayer graphene (tBLG), consisting of two simple monolayer graphene (Fig. 4.3a), can be thought of as simpler van der Waals heterostructure. Due to the relative rotation between two graphene layers, similar moire pattern is induced. The induced moire potential together with interlayer coupling leads to the band modulation and yields rich novel phenomena, e.g. van Hove singularity (saddle point in band structure) [1, 2, 3, 17], predicted suppressed Fermi velocity at small twisting angles [3, 4, 5, 6, 7], and even the recently reported Mott-like insulating states and doping-induced superconductivity at magic angles [8, 9].