Switching the Properties of Layered Materials through Intercalation, Defects and External Fields from First Principles

Layered van der Waals materials, such as transition metal dichalcogenides (TMDs), are a promising platform for applications as diverse as optoelectronics, energy storage, and quantum information in large part due to the tunability of their electronic, optical and structural properties. Both ground- and excited-state properties can be sensitively modified both during and after synthesis through methods such as ion intercalation, stacking and twisting, the introduction of defects, and coupling to external fields. In this talk, I will explore three different pathways for switching the properties of layered TMDs. Firstly, I will present our recent first principles work on ion intercalation induced phase transitions in different TMD heterostructures, including an intercalation-induced charge density wave (CDW) phase transition in WTe2. Secondly, we will explore structural defects present in TMDs, routes for passivating these defects, and magnetic order arising from defect complexes. Finally, we will explore how many-body effects modify the nonlinear optical response of 2D materials and the coupling to strong external fields beyond the perturbative regime.