Quasiperiodicity and emergent symmetries in twisted graphene multilayers
Sergio de la Barrera
University of Toronto
Wednesday, January 29, 2025
2:00 p.m.
In-person: QNC 1201
Abstract: Layering two-dimensional periodic materials to form moiré structures is a convenient method of constructing emergent periodicity with length scales in between those typical of crystals and optically defined atomic lattices. This scheme has proven fruitful for engineering new electronic structures with on-demand properties like superconductivity, strong electronic interactions, and topology. In contrast, quasiperiodic structures, without periodicity or a Bloch description, have proven more challenging to engineer and to understand. Here, I demonstrate how moiré lattices can be used to construct quasiperiodicity with both a high degree of tunability and conditions favorable for interacting electronic phenomena. I will discuss a graphene-based realization of a moiré quasiperiodic system that exhibits a wide array of phenomena, including superconductivity, flavor symmetry-breaking, quantum oscillations, and signatures of both periodic-like and quasiperiodic regimes in the electronic structure. Next, I will introduce a related periodic graphene moiré system that exhibits signatures of topological bands that arise from an emergent broken symmetry in the structure.