Observation of inter-edge magnetoplasmon mode in a degenerate two-dimensional electron gas

We study the propagation of edge magnetoplasmons by time-resolved current measurements in a sample which allows for selective detection of edge states in the quantum Hall regime. We observe two decoupled modes of edge and inter-edge magnetoplasmons at filling factors close to 3. From the analysis of the propagation velocities of each mode the internal spatial parameters of the edge structure are derived.