Observation of audio-frequency edge magnetoplasmons in the classical two-dimensional electron gas

The electric admittance of a two-dimensional electron gas on liquid helium measured at audio frequencies {ω} is observed to oscillate as a function of magnetic field at strong magnetic fields. The oscillations can be attributed to the propagation of very-low-frequency ({ω}{τ}{~}10^-6, {τ} scattering time; {ω}/ωc{~}10^-8, ωc cyclotron frequency) edge magnetoplasmons. The directly determined dispersion relation agrees with theory and quantitatively with measurements in the collisionless regime ({ω}{τ}{}1). The attenuation, theoretically obtained by incorporating the screening in a simple local-capacitance model, agrees well with experiments.