THERMOELECTRIC PROPERTIES OF GAAS GA1-XALXAS HETEROJUNCTIONS IN THE FRACTIONAL QUANTUM HALL REGIME/

We present experimental data on the thermoelectric power of a two-dime nsional electron gas in the fractional quantum Hall regime. The thermo power is shown to be due to phonon-drag and therefore reflects the cou pling of phonons to the electronic quasiparticle states. The general b ehaviour of the thermoelectric power as a function of applied magnetic field and temperature is compared to recent theoretical predictions o f the electron-phonon drag in quantizing magnetic fields.