Colloquium on April 28 (Friday) 2:00 pm in Fretwell 315

 

Abstract: Atomic-scale lattice mismatches and twist angles in vertically stacked assemblies of 2D materials such as graphene create moiré patterns, which have received intense attention by physicists in recent years as they exhibit new emergent physical phenomena. This talk focuses on two topics relevant to the analysis and computational prediction of properties of 2D moiré materials: atomic relaxation and topological transport. Weak van der Waals forces between layers over large moiré scales induce atomic relaxation of 2D heterostructures, affecting macroscopic properties of the material. We will discuss a computationally accessible model for predicting this relaxation and present analytical and numerical results.  Additionally, we will present effective Dirac models for topological modes propagating along domain walls in the presence of large gapped moiré domains, discussing the rigorous definition of topological edge invariants associated with massive Dirac operators and their robustness with respect to perturbations and geometries such as domain wall junctions.