  We find that the Berry curvature splits the edge plasmons propagating along
the opposite directions in quantum anomalous Hall insulators even with
vanishing Chern number. When the bulk is insulating, only one unidirectional
edge plasmon mode survives whose direction can be changed by external fields.
The unidirectional edge plasmon in the long-wavelength limit is acoustic and
essentially determined by the anomalous Hall conductivity. The group velocity
of the chiral edge plasmon would change its sign for a large wave vector, which
originates from the k-quadratic correction to the effective mass. The impacts
of the Fermi level and the wave vector on the bulk and edge plasmons are
discussed. Our work provides a well quantitative explanation of the recent
observation of the chiral edge plasmon in quantum anomalous Hall insulators and
some insight into the application of realistic topological materials in chiral
plasmonics.
