NOVEL MODE OF EDGE MAGNETOPLASMON OSCILLA TIONS IN ELECTRON-SYSTEM OVER LIQUID-HELIUM

A study has been made of the characteristics of a novel mode of edge m agnetoplasmon oscillations (EMP) in the sheet of surface electrons ove r superfluid helium. The experiments have been carried out into a cell of rectangular geometry in temperature range of 0.4-1.6 K at frequenc ies 1.5-5 MHz and electron concentration of 2.10(8) cm(-2), and in mag netic fields up to 0.15 T. For detailed analysis of data obtained, the phase of signal passed through experimental cell was calculated under the excitation of EMP. It is shown that the frequency of the new mode similar to that observed in Ref. 12, is 3-4 times lower than the freq uency of familiar EMP arid its dependence on magnetic field is omega s imilar to 1/B which coincides with a similar dependence of familiar EM P. Positions of resonances of the new mode observed are in agreement w ith a theoretical model developed by Monarkha, which describes the osc illations of electron sheet boundary and electron density in. opposite phases in EMP.