Effect of Coulomb interaction on microwave-induced magnetoconductivity oscillations of surface electrons on liquid helium.

The experimental observation of the strong Coulombic effect on magneto-oscillations of the photoconductivity of surface electrons in liquid helium is reported. The observed broadening of the oscillations and shifts in positions of conductivity extrema with increasing electron density are in good agreement with the linear transport theory, which takes into account an internal electric field of fluctuational origin. These results provide important evidence for identification of the mechanism of the oscillations and zero-resistance states developed in their minima.