The propagation of low-frequency edge excitations in a two-dimensional electron gas in the IQHE regime

Recent theoretical studies predict a rich spectrum of edge excitations in a 2DEG in the QH regime. Experimental verification of the theory is hindered by the fact that many of these excitations are uncoupled (neutral) or weakly coupled with an external alternating electric field. We discuss the use of gates for the mutual transformation of coupled and uncoupled excitations with an external field in IQH regime. This process provides a method for the excitation and detection of neutral edge excitations. We report results of the first experimental study of the transmission of edge excitations through a gate-induced potential barrier. A strong oscillatory dependence of the magnitude of transmitted edge magnetoplasmons as a function of the gate voltage was observed. Results of an experiment with two gates in series, where one gate was intended to be the source and the second to be the detector of a neutral edge excitation, give evidence that more than one type of edge excitation can propagate along a 2DEG edge. We discuss our data in terms of existing models of low-frequency edge excitations.