Solution: Magic Moiré in Twisted Graphene

Materials science was rocked recently by an amazing discovery: When a layer of graphene, a sheet of carbon crystal with atoms arranged in a one-atom-thick hexagonal lattice, is dropped on another one and rotated to just the correct angle, the resulting bilayer graphene magically acquires the ability to become superconductive. Our June Insights puzzle explored a set of simple questions designed to give some intuitive understanding of the geometric properties that make this happen. One of the factors that cause this effect is the fact that the two slightly misaligned sheets interfere with each other to produce larger-grained moiré patterns, which have long been familiar to people in diverse fields such as visual artists, fabric makers and photographers.