Tailoring light-matter interactions in layered van der Waals materials.

Two-dimensional (2D) materials —such as graphene and monolayers of transition
metal dichalcogenides (TMDs)— exhibit exceptional light-matter interactions due to
their reduced dimensionality and unique crystal symmetries. While only a few dozen
layered compounds have been experimentally synthesized, theoretical predictions
suggest that over 5,000 stable 2D materials await discovery, with properties ranging
from semiconducting to magnetic and topological. By stacking or twisting different
layers, we can form van der Waals heterostructures and moiré patterns that offer new
ways to control their behavior. This tunability has led to the rapidly growing field of
twistronics.
In this talk, I will present insights from our recent optical studies of atomically thin
semiconductors, focusing on how excitons —bound electron-hole pairs created after
light absorption— govern many of their optical properties. I will discuss how the
energies of these excitonic states can be tuned using electric and magnetic fields or
by adjusting the twist angle between layers. I will also highlight strategies for confining
and guiding excitons, which could support future excitonic circuits for information
processing. Finally, I will briefly show how carrier density, mechanical strain, alloying,
and coupling to photonic nanoantennas provide additional routes for tailoring lightmatter
interactions in these materials.