Quantum transport of surface electrons over liquid helium in magnetic field

The magnetoconductivity Σ _xx of surface electrons over liquid helium at electron densities (1–9) × 10⁸ cm⁻² is measured at temperatures down to 0.5 K and magnetic fields H up to 25 kOe. Σ _xx is shown to decrease with increasing H. For rather high temperatures and low magnetic fields dependence Σ _xx ⁻¹ on H displays a classical behavior, but as the temperature is reduced or H is increased, a transition to the quantum magnetotransport regime occurs. It is shown that Σ _xx decreases at lowering temperature, passes through a minimum and then slightly increases in the region of electron-ripplon scattering. The measured data are in good agreement with the theoretical results taking into account the preferable contribution of electron scattering on ripplons with wavelength near magnetic length. At the region of electron crystal Σ _xx is weakly dependent on T. At low magnetic field Σ _xx ⁻¹ increases with H linearly and, at H>17kOe, Σ _xx ⁻¹ ~ H ^1.5.