Using symmetry of topological defects to find emergent quantum states in 2D materials*

Extended topological defects in materials, such as domain walls and vortices, can host new electronic states. Such quantum states are often sensitive to the symmetry of the material, but these symmetries are altered by the topological defects (for example, by imposing mirror symmetry at a mirror twin boundary). Thus by controlling the symmetries of these defects, we can control their quantum properties, such as by altering topological invariants of topological insulators. In this talk, I will discuss how we developed a framework to categorize the possible symmetry groups of these defects in two-dimensional materials. Using this, we identified promising symmetries and their manifestation in real materials which were subsequently calculated explicitly with first-principles calculations. Our results set the groundwork for using such symmetry-based analysis for rapid screening of databases of materials to identify those which may host physically interesting defects with novel quantum states for energy-efficient electronics or quantum computing.