MANY-ELECTRON TRANSPORT IN STRONGLY CORRELATED NONDEGENERATE 2-DIMENSIONAL ELECTRON-SYSTEMS

We consider static conductivity and cyclotron resonance in a two-dimen sional electron fluid and Wigner crystal. The theory is nonperturbativ e in the electron-electron interaction. It is formulated in terms of a Coulomb force that drives an electron due to thermal fluctuations of electron density. This force is used to describe the effect of electro n-electron interaction on short-wavelength electron scattering by defe cts, phonons, and ripplons, and thus on electron transport. In a broad parameter range the force is uniform over the electron wavelength, an d therefore the motion of an electron in the field of other electrons is semiclassical. In this range we derive the many-electron quantum tr ansport equation and develop techniques for solving it. We find the st atic conductivity sigma. Many-electron effects may ''restore'' Drude-t ype behavior of sigma in the range from zero to moderate classically s trong magnetic fields B, whereas in quantizing fields sigma increases with B, i.e., the conductivity is a nonmonotonous function of B. Many- electron effects give rise also to a substantial narrowing of the cycl otron resonance absorption peak compared to what follows from the sing le-electron theory. The shape of the peak is found for both fast and s low rate of interelectron momentum exchange as compared with the relax ation rate. We apply the results to electrons on helium and explain wh y different types of B dependence of sigma are observed.