Collective Excitations in a Two-Dimensional Electron System on Liquid Helium-4 under Cyclotron Resonant Condition

摘要

We investigate low-frequency collective excitations in a two-dimensional electron system on liquid helium-4 subject to high-frequency cyclotron resonant excitation in strong magnetic field. Under the cyclotron resonant excitation the frequency of the edge magnetoplasmon resonant mode shifts with respect to that in equilibrium. In addition, a novel collective excitation mode is observed. These findings are consistent with the conclusion of previous studies about the quasi-3D nature of the excited state of the system.