Prof. Allan MacDonald, Department of Physics, University of Texas at Austin

"Moiré Patterns in Two-Dimensional Materials"

Coffee and cookies will be served at 3:45pm in RLM 4.102

Abstract: According to Wikipedia a moiré pattern is a large scale interference pattern that is produced when an opaque regular pattern with transparent gaps is overlaid on another similar pattern with a different pitch or orientation.  Moiré patterns are ubiquitous in two-dimensional van der Waals materials in which the regular patterns formed by two-dimensional crystals, differences in pitch are established by differences in lattice constants, and differences in orientation can be controlled experimentally.  The electronic properties of two-dimensional semiconductor, gapless semiconductor, and semimetal systems in which moiré patterns have been established have continuum model Hamiltonians with the periodicity of the moiré pattern.  I will discuss some examples of new physics that can be explored using van der Waals material moiré patterns, comment on the recent discovery of superconductivity in magic angle twisted bilayer graphene, and speculate on interesting future directions.