Correlated Electrons in Rotationally Controlled van der Waals Heterostructures

Seed Image

This seed proposal by a team of PIs aims to establish rotationally controlled van der Waals heterostructures as a platform for correlated quantum states in reduced dimensions. Examples include electron-hole pairs (excitons), electron-electron or hole-hole pairs (Cooper pairs), and their respective Bose-Einstein condensates. Two platforms are currently being investigated, both experimentally and theoretically. Controlled moiré patterns in twisted bilayer and multilayer graphene heterostructures are used to realize flat bands which host correlated insulators and superconducting states. The optimum conditions in which these states emerge, as well as the microscopic nature of the correlated insulators are some of the main questions this effort seeks to answer. A second materials platform consist of rotationally controlled double layers of two-dimensional materials separated by a tunnel barrier. We are using tunneling between the two layers and Coulomb drag to probe collective states that form as a result of inter-layer interaction.