Magnetoplasmon excitations from integer-filled Landau levels in narrow-gap quantum wells.

We report a theoretical study on magnetoplasmon excitations in a perpendicular magnetic field in n-type narrow-gap quantum wells (QWs). Using the Hartree-Fock approximation based on the 8 × 8 k · p Hamiltonian, we calculate magnetoplasmon dispersions in symmetric and asymmetric InAs/AlSb QWs for the case of integer-filled Landau levels. We demonstrate a significant dependence of the shape of magnetoplasmon dispersions on the 2D electron concentration, as well as a nonlinear dependence of the magnetoplasmon energy on the wavevector at small values of k. Both effects are shown to result from strong mixing between the conduction (Γ6) and the valence (Γ7 and Γ8) bands. We find that cyclotron-resonance (CR) energies are affected by electron-electron interaction due to Kohn theorem violation and predict the interaction-induced enhancement of the CR line splitting in the case of even (Δg-splitting) and odd (Δm-splitting) filling factors for the Landau levels.