Mapping the spatial modulations of excitons in moiré heterostructures

Moiré heterostructures of layered materials such as transition metal dichalcogenides enable periodic arrays of localized quasi-particles with long-range Coulomb interactions which can host a plethora of quantum phenomena. Depending on the lattice mismatch and twist angle across the individual layers, resulting moiré potential modulates the distribution of electronic states, significantly changing the landscape of moiré excitons and their characteristics. We employ simultaneous hyperspectral electron energy loss spectroscopy and annular dark field imaging in a scanning transmission electron microscope to investigate WS2/WSe2 heterostructures at the nanoscale. Through this technique, we present the mapping of intralayer moiré excitons within a moiré supercell, shedding light on the interplay between interlayer coupling and atomic reconstruction. Our observations provide valuable insights into the mechanisms governing the formation and confinement of moiré excitons in these systems.