Quantum corrections to conductivity: from weak to strong localization

Results of detailed investigations of the conductivity and Hall effect in gated single quantum well GaAs/InGaAs/GaAs heterostructures with two-dimensional electron gas are presented. A successive analysis of the data has shown that the conductivity is diffusive for k F l = 25 − 2. The absolute value of the quantum corrections for k F l = 2 at low temperature is not small, e.g., it is about 70 % of the Drude conductivity at T = 0 . 46 K. For k F l = 2 − 0 . 5 the conductivity looks like diffusive one. The temperature and magnetic field dependences are qualitatively described within the framework of the self-consistent theory by Vollhardt and W¨olfle. The interference correction is therewith close in magnitude to the Drude conductivity so that the conductivity σ becomes significantly less than e 2 /h . We conclude that the temperature and magnetic field dependences of conductivity in the whole k F l range are due to changes of quantum corrections.