UNIVERSAL BEHAVIOR OF MAGNETOCONDUCTANCE DUE TO WEAK-LOCALIZATION IN 2 DIMENSIONS

Magnetoconductance due to weak localization is studied experimentally for different semiconductor heterostructures. We observe that, when pr esented as a function of the appropriately normalized magnetic field, different samples show Fiery similar high-field behavior. A theoretica l description is developed that allows one to describe in a consistent way both the high-and low-field limits. The theory predicts universal magnetic field dependence (B-1/2) of the conductivity correction for two-dimensional systems in the high-field limit. Low-field magnetocond uctance depends strongly on spin and phase relaxation processes. Compa rison of the theory with experiment confirms the universal behavior in high fields and allows one to estimate the spin and phase relaxation times.