Doping-dependence of exciton energies and MCD in TMD moiré superlattices*

The long-period pattern formed by two-dimensional crystals that are slightly misaligned or have slightly different lattice constants is known
as a moire superlattice. It was recently discovered that the moiré superlattices have a pronounced effect on the electronic properties of many two-dimensional materials. I will discuss the influence of a moiré superlattice on excitons in transition metal dichalcogenide heterostructures.
Existing effective boson theories of the moiré excitons do not allow the effect of electron or hole doping to be predicted. I will present a microscopic calculation of the optical response at finite doping, as well as a simple phenomenological model, which captures the main results.
When the carriers are valley polarized the optical response exhibits circular dichroism. I will discuss the use of the circular dichroism of the exciton spectrum as a probe of ground state valley polarization.