Magneto-optical conductivity of a band-inverted charge transfer insulator

Abstract

Recently, quantum anomalous Hall state has been observed in moiré transition metal dichalcogenide bilayers. Its topological physics can be explained by a band-inverted charge transfer insulator model, in which the topological phase transition occurs in the presence of the band inversion. Starting from an effective three-band low-energy model, we investigate the Landau levels and the magneto-optical conductivity of a band-inverted charge transfer insulator on the honeycomb lattice. We derive the real and imaginary parts of the longitudinal conductivity and Hall conductivity using Kubo formalism. We find that the magneto-optical conductivity indicates a discontinuity at the point of band inversion in the low-frequency regime, which can serve as a probe for band topology. It is shown that the charge transfer gap, chemical potential, and magnetic field have a sensitive effect on the magneto-optical conductivity. The unique band structure also changes the peaks in the imaginary part of the Hall conductivity into two distinct contributions of opposite signs. We also study the relationship of the band-inversion signature and transport properties and highlight its distinct features that can be probed experimentally.