DMS Applied and Computational Mathematics Seminar

Speaker: Alexander Watson (University of Minnesota Twin Cities)

Title: Multiple-scales perspective on moiré materials 

Abstract: In recent years, experiments have shown that twisted bilayer graphene and other so-called "moiré materials" realize a variety of important strongly-correlated electronic phases, such as superconductivity and fractional quantum anomalous Hall states. I will present a rigorous multiple-scales analysis justifying the (single-particle) Bistritzer-MacDonald PDE model, which played a critical role in the prediction of these phases in twisted bilayer graphene. The significance of this model is that it has moiré-periodic coefficients even when the underlying material is aperiodic at the atomic scale. This allows moiré materials to be studied via Floquet-Bloch band theory, a variant of the Fourier transform. I will then discuss generalizations of this model and other mathematical questions related to moiré materials.