Excitons in Flatland: Exploring and Manipulating Many-body Effects on Optical Excitations in Low-Dimensional Materials

ABSTRACT: Since the isolation of graphene in 2004, atomically-thin quasi-two-dimensional (quasi-2D) materials have proven to be an exciting platform for both applications in novel devices and exploring fundamental phenomena arising in low dimensions. This interesting low-dimensional behavior is a consequence of the combined effects of quantum confinement and stronger electron-electron correlations due to reduced screening. In this talk, I will discuss how the optical excitations (excitons) in quasi-2D materials, such as monolayer transition metal dichalcogenides and few-layer black phosphorus, as well as other reduced dimensional materials, differ from typical bulk materials. In particular, we will look at how defects and heterostructures can be used to tune the optical properties of materials in reduced dimensions, and how the effects of symmetry and dimensionality manifest in features of exciton dynamics and transport. I will also discuss new methods we have developed to simulate exciton dynamics and core-level excitations associated with x-ray absorption spectra.