Surface acoustic wave study of a double layer AlGaAs/GaAs 2D hole system

The temperature and frequency dependence of the surface acoustic wave (SAW) velocity shift has been studied in a double layer 2DHS for 0.34-4.2 K and 112-560 MHz. The measured velocity shift has been compared to the velocity shift calculated from conventional transport techniques. At nu = 1, 2, 4, 6 and 8 maxima in SAW velocity shift have been detected. A hysteretic featur e at nu = 2 has been observed in both conventional magnetotransport and SAW measurements, which is probably due to slight parallel conduction. (C) 200 1 Elsevier Science B.V. All rights reserved.