Plasmonic detection of the parity anomaly in a two-dimensional Chern insulator

In this paper, we present an analytic study on the surface plasmon polaritons in a two-dimensional parity anomaly Chern insulator. The two-dimensional conductivities derived from the BHZ model are antisymmetric, based on which two surface plasmon modes each contains two branches of dispersions have been found. In the absence of parity anomaly, the half-integer-valued Hall conductivities with positive and negative Dirac mass terms differ by a sign; two branches of each surface plasmon mode are exactly degenerate. However, the parity anomaly can lift such degeneracy and lead to significant modifications of these dispersion curves or even the occurrence of an extra branch of surface plasmons under particular condition. Our investigations have revealed the effects of the interplay of parity anomaly and topology on the dispersion relations of the surface plasmon polaritons, which may pave a possible way for the detection of the parity anomaly in a two-dimensional Chern insulator via plasmonic responses.