HIGH-FREQUENCY EDGE EXCITATIONS IN THE QUANTUM HALL REGIME

We report phase sensitive measurements of microwave propagation throug h a high mobility two dimensional electron gas subjected to a perpendi cular magnetic field. Two types of configurations were used, one that allows all wave vectors q, and one that selects only specific q values . The spectrum of edge excitations was studied over a broad frequency span, which allowed us to observe the logarithmic dispersion of edge m agneto-plasmons. (C) 1998 Elsevier Science B.V. All rights reserved.