Nonlinear acoustoelectric transport in a two-dimensional electron system

We study both theoretically and experimentally the nonlinear interaction be tween an intense surface acoustic wave and a two-dimensional electron plasm a in semiconductor-piezocrystal hybrid structures. The experiments on hybri d systems exhibit strongly nonlinear acoustoelectric effects. The plasma tu rns into moving electron stripes, the acoustoelectric current reaches its m aximum, and the sound absorption strongly decreases. To describe the nonlin ear phenomena, we develop a coupled-amplitude method for a two-dimensional system in the strongly nonlinear regime of interaction. At low electron den sities the absorption coefficient decreases with increasing sound intensity , whereas at high electron density the absorption coefficient is not a mono tonous function of the sound intensity. High-harmonic generation coefficien ts as a function of the sound intensity have a nontrivial behavior. Theory and experiment are found to be in a good agreement.