Magnetoplasmon excitations in double-quantum-well systems in a parallel magnetic field

The magnetoplasmon dispersion relation is obtained in the random-phase approximation for a double-quantum-well structure, where the magnetic field is parallel to the planes and only the two lowest tunneling states are included in the formalism. Analytic closed-form results are presented in the quasiclassical limit when tunneling between the quantum wells is included to lowest order. The cases when the Fermi level is above, within, or below the gap are presented. Numerical results are given for plasmon propagation parallel and perpendicular to the applied magnetic field. When the plasmon wave vector is parallel to the magnetic field, there is only one branch for the symmetric mode of plasmon excitation but the antisymmetric modes have two branches when the Fermi level is above or within the gap. For plasmon propagation perpendicular to the magnetic field, a coupling of the symmetric and antisymmetric modes is obtained.