Strained bilayer graphene, emergent energy scales, and moiré gravity

Twisted bilayer graphene is a rich condensed matter system, which allows one to tune energy scales and electronic correlations. The low-energy physics of the resulting moir\'e structure can be mathematically described in terms of a diffeomorphism in a continuum formulation. We point out that twisting is just one example of moir\'e diffeomorphisms. Another particularly simple and experimentally relevant transformation is a homogeneous isomorphic...