Acoustoelectric study of localized states in the quantized Hall effect

Abstract

The acoustoelectric effect caused by momentum transfer from a surface acoustic wave to a two-dimensional electron system is employed to investigate the quantum Hall effect. Strong quantum oscillations of both the acoustoelectric fields and currents are observed and in part explained by a recent model, based on a local description of the conductivity. However, an unexpected bipolar acoustoelectric Hall voltage occuring at integer filling factors is related to localized electron- and hole-like states in the tails of Landau levels. A similar signal is also observed at filling factor v = 5 2 .