Magnetoconductivity of two-dimensional electrons on liquid helium:Experiments in the fluid phase

The magnetoconductivity σ(B) of two-dimensional electrons on liquid helium was measured from 0.25 to 1.3 K in the electron fluid phase in magnetic fields up to 8 T. In low magnetic fields B, σ(0)/σ(B)=1+(μB(Formula presented) as in the Drude model, where μ is the zero-field mobility due to scattering by (Formula presented) vapor atoms and ripplons, even for μB≫:1. The values of mobility are in good agreement with previous measurements and with calculations for a correlated electron fluid. At higher fields, σ(0)/σ(B) deviates from the Drude model and becomes density dependent due to many-electron effects. Only at the highest fields, or the lowest densities, does σ(B) approach the theoretical single-particle magnetoconductivity. For both vapor-atom and ripplon scattering the results are in good agreement with a microscopic many-electron theory in which the diffusion of the cyclotron orbits is controlled by the internal fluctuational electric fields. The density and temperature dependence of these internal fields derived from the experiments are in excellent agreement with Monte Carlo simulations.