A framework to study twisted bilayer graphene in a tight binding model
A framework to study twisted bilayer graphene in a tight binding model
The study of the electronic properties of twisted bilayer graphene (TBG) has听 garnered much attention from the condensed matter community recently. TBG is听 obtained by stacking two graphene monolayers on top of each other, and听 rotating one of them with respect to the other. Theoretical and experimental听 analyses have found that the electronic properties of TBG depend very听 strongly on the angle between the layers. In fact, a handful of "magic" angles have been predicted at which TBG becomes a supercondutor, and this has听 even been verified experimentally.
The model commonly used to study TBG is an effective one, and was derived by听 Bistritzer and MacDonald. In this talk, I will present recent results on听developing a framework to study TBG from first principles. To be more exact,听 we consider a tight-binding model for the electrons, but make no further听approximations. Using a renormalization group technique, we construct a听 perturbative expansion to study TBG that is convergent when the twisting听angle satisfies certain diophantine conditions.
This is joint work with V. Mastropietro.