Dynamic interaction of bulk acoustic waves with a two-dimensional electron gas at an ${\mathrm{Al}}_{\mathit{x}}$${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As/GaAs heterojunction in strong magnetic fields

The results of a theoretical and experimental study of the interaction of longitudinal coherent bulk acoustic waves at 9.3 GHz with two-dimensional electron gas (2DEG) at a GaAs/${\mathrm{Al}}_{\mathit{x}}$ ${\mathrm{Ga}}_{1\mathrm{-}\mathit{x}}$As heterojunction in a strong magnetic field are given. The theory of the linear 2DEG response to an incident bulk acoustic wave is developed, based on a system of quantum kinetic equations. The importance of disorder in the 2DEG and the coupling of the acoustic waves to the localized states is demonstrated. A comparison of the theoretical results with experiment is given.