Physics Colloquium
Moiré materials and incommensurability-driven phases in two-dimensions Justin Wilson Postdoctoral Associate
Department of Physics and Astronomy
Rutgers School of Arts and Sciences

Abstract
Recently, condensed matter physics has been captivated by a series of experiments showing superconductivity and correlated insulating phases in twisted bilayer graphene (TBG). TBG is composed of two sheets of graphene, carefully stacked on top of each other but physically twisted to reveal a moiré pattern. At small twist-angles (around 1 degree, the "magic angle"), kinetic energy dramatically decreases, allowing correlated phases unavailable in single graphene sheets to appear. TBG is one of the first in a set of materials called moiré materials, a whole class that allows unprecedented control thanks to the engineered superlattice appearing on the moiré pattern. However, these moiré patterns are in general incommensurate. In fact, TBG belongs to a subclass of moiré materials we discovered and called "magic-angle semimetals," which all show similar noninteracting phenomenology. We found that some of these models can be built with single layers of cold-atomic gases and meta-materials, bringing magic-angles to new platforms and allowing for experiments to test theories under controlled conditions. Furthermore, at the "magic-angle," these models show a vanishing quasiparticle velocity, flat bands, and criticality. We postulate that the resulting metallic phase is unstable to correlations. Modifying the models to include topology, we can again see flat bands and criticality, hinting at a universal principle and a controllable platform for correlated phases.

Research Interests
Statistical Mechanics, computer simulations, aging dynamics, coarsening processes, nonequilibrium critical dynamics, rheology of glassy systems and complex fluids, granular materials and jamming transition, active matter, spin glasses, supercooled liquids, amorphous materials.