Observation of Novel Edge Excitations of a Two-Dimensional Electron Liquid on Helium in a Magnetic Field

Abstract

Low-frequency edge excitations in a magnetic field of the two-dimensional electron system on liquid helium are studied. It is found that, in addition to the conventional edge magnetoplasma resonances, novel resonances of smaller amplitude appear at lower frequencies at $T<0.9$ K. A comparison of these new modes with the recently predicted acoustic edge excitations is presented. The propagation of boundary oscillations of the electron sheet as well as their coupling to edge magnetoplasmons are also discussed to explain the observed phenomena.