Modeling topological edge magnetoplasmons in a quantum anomalous Hall insulator

Microwave impedance microscopy (MIM) has been widely used to probe the local electromagnetic properties of quantum materials in the GHz regime. The traditional way to interpret the MIM signal is to relate the microwave response to the local electrical conductivity and permittivity scalars. In this work, we develop a theoretical framework that models the microwave response of quantum anomalous Hall (QAH) insulators using a full conductivity tensor description. Our numerical simulations reveal topological edge magnetoplasmons (EMP) that propagate along the edge of QAH samples, which can only be captured in our full tensor description. This allows us to distinguish topological edge currents from trivial conduction channels, which can be achieved by performing microwave imaging experiments in the frequency domain.