Fluctuational-field-induced narrowing of the quantum cyclotron resonance from two-dimensional electrons on the surface of superfluid helium

We have observed strong narrowing of the quantum cyclotron resonance (CR) l inewidth of surface electrons on liquid helium, which is caused by the many -electron fluctuational field. In the reported experiment, the amplitude of the internal fluctuational electric field was varied by changing the elect ron density (linear CR regime) and electron temperature (nonlinear CR regim e). The observed Coulombic effect is interpreted as an inelastic suppressio n of the collision broadening of Landau levels due to the ultra-fast drift velocities of the electron orbits in the strong fluctuational many-electron field. (C) 2000 Published by Elsevier Science B.V. All rights reserved.