COMPOSITE FERMION SIGNATURE IN THE ACOUSTOELECTRIC EFFECT IN 2DES AND2DHS

The integer and fractional quantum Hall effects have been investigated using the acoustoelectric effect in both two-dimensional hole and ele ctron systems fabricated by MBE on GaAs. Measurements have been made o f the longitudinal and transverse acoustoelectric voltages as a functi on of magnetic field up to 16T at a temperature of 340 mK. We report b ehaviour close to v = 1/2 in the dispersion and acoustoelectric effect that cannot be explained on the basis of quasi-DC measurements. Final ly, we find that a tensor relationship exists in the acoustoelectric e ffect similar to that reported recently in thermoelectric measurements . (C) 1998 Elsevier Science B.V. All rights reserved.