Spatial-dispersion-induced acoustic anisotropy in semiconductor structures

We demonstrate that a Rayleigh surface acoustic wave (SAW) propagating on the surface of a (001)-oriented GaAs quantum well structure induces different optical properties for propagation directions along the [110] and the $\left[1¯10\right]$ symmetry axes. The nonequivalence of the two directions is attributed to the lift of the fourfold rotation symmetry of the optical and acoustic properties around the [001] growth axis by the finite wave vector of the SAW, a spatial dispersion effect which is also expected for bulk modes in zinc blende semiconductors.