Commensurability oscillations in the surface-acoustic-wave-induced acoustoelectric effect in a two-dimensional electron gas

We study the acoustoelectric effect generated by surface acoustic waves (SAW) in a high-mobility two-dimensional electron gas with isotropic and especially small-angle impurity scattering. In both cases the acoustoelectric effect exhibits Weiss oscillations periodic in $B^{-1}$ due to the commensurability of the SAW period with the size of the cyclotron orbit and resonances at the SAW frequency $\omega =k{\omega }_c$ multiple of the cyclotron frequency. We describe how oscillations in the acoustoelectric effect are damped in low fields where ${\omega }_c{\tau }_{*}\lesssim 1$ (with the time scale ${\tau }_{*}$ dependent on the type of scattering) and find its nonoscillatory part, which remains finite to the lowest fields.