Speaker
Description
Light–matter interactions enable out-of-equilibrium and equilibrium states in quantum solids and can give rise to new correlated phases. I will present our recent work on intralayer moiré excitons in twisted TMD systems. Using Bethe–Salpeter calculations based on a continuum electronic-structure model, we show that Coulomb exchange strongly influences these excitons, and that valley polarization and singlet–triplet splitting are tunable by twist angle. I will then describe an emergent, purely electronic type-II multiferroicity in partially doped moiré TMD heterobilayers, where Coulomb interactions stabilize intervalley-coherent pseudospin order and strain acts as a gauge field that drives a collinear pseudospin ferromagnet into a noncollinear cycloidal texture of finite vector chirality — a chiral electronic texture that yields macroscopic electric polarization with no ionic displacement, and whose reversal under reversed strain gives deterministic magnetoelectric control.