We investigate the electrodynamic properties of charged edge excitations in the fractional quantum Hall regime by means of time-resolved magnetotransport. In samples with a smooth edge potential and an additional screening electrode, the propagation velocity of high frequency signals is related to the width of fractional edge channels. While the observed edge magnetoplasmons around filling factor 1/3 hint at a similar electronic edge structure as around filling factor 1, characteristic deviations appear for other fractions, especially around $\nu =2\mathrm{}/3$.

• Received 23 June 1997

DOI:https://doi.org/10.1103/PhysRevLett.79.3748