Surface polaritons in a GaAs/AlGaAs heterojunction in a high magnetic field

The spectrum of the surface polaritons (SP) in a GaAs/AlGaAs heterojunction in the presence of a large transverse quantizing magnetic field is calculated under the quantum Hall effect conditions. The dispersion properties of the SPs are studied taking into consideration the values of the dielectric constants of the GaAs and the AlxGa1-xAs media, and the finite thickness, d, of the AlxGa1-xAs layer. It is shown that in the vicinity of the electron cyclotron resonance, the SPs become slow waves, and their group velocity exhibits stepwise behaviour. The magnitude of these steps is determined by the fine-structure constant, alpha = <e(2)/(h)over bar c>, the thickness d of the AlxGa1-xAs layer, and the dielectric constants of GaAs and AlxGa1-xAs. It is found that the values of the phase and the group velocities of the SPs can significantly decrease with increasing thickness, d, of the AlxGa1-xAs layer and with increasing difference between the dielectric constants of GaAs and AlxGa1-xAs. Numerical results for the dispersion curves are presented for representative cases. The possibility of experimental observation of the effects considered is discussed.