SURFACE-ACOUSTIC-WAVE SCATTERING IN QUANTUM-WIRE ARRAYS - THEORY AND EXPERIMENT

We have investigated anisotropic surface acoustic wave (SAW) scatterin g from quantum wire arrays as a function of electron concentration and magnetic held, and we have used Fermi's golden rule to model the SAW scattering. With the SAW perpendicular to the wires we observe oscilla tions in the transmitted intensity, reflecting the magnetic depopulati on of ID subbands, and this agrees well with the theory. With the SAW parallel to the wires the theory predicts negligible attenuation, and this is confirmed experimentally at low electron concentrations. Surpr isingly, at high electron concentrations the SAW attenuation increases sharply in this orientation to the point where it is three times larg er than in the unstructured 2DEG. We speculate that this is due to the excitation of intraband 2D plasmon-like modes.