Shining light on collective modes in moir'e fractional Chern insulators
The study investigates collective excitations and optical responses in moiré fractional Chern insulators (FCIs), which differ significantly from standard quantum Hall states. Researchers found new, optically active low-energy modes called "fractional excitons" that appear as sharp peaks in optical conductivity. These modes are highly tunable by a displacement field and reveal how moiré potentials alter spectral weight.