Surface acoustic wave induced magnetoresistance oscillations in a 2D electron gas

We study the geometrical commensurability oscillations imposed onto the resistivity of 2D electrons in a perpendicular magnetic field by a propagating surface acoustic wave (SAW). We show that, for $\omega <{\omega }_c$, this effect is composed of an anisotropic dynamical classical contribution increasing the resistivity and the non-equilibrium quantum contribution isotropically decreasing resistivity, and we predict the appearance of zero-resistance states associated with geometrical commensurability at large SAW amplitude. We also describe how the commensurability oscillations modulate the resonances in the SAW-induced resistivity at multiples of the cyclotron frequency.