Quantum corrections to conductivity: From weak to strong localization

Abstract

The 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 ${k}_{F}l=25\ensuremath{-}2.$ 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 $T=0.46\mathrm{K}.$ For ${k}_{F}l=2--0.5$ the conductivity looks like the diffusive one. The temperature and magnetic field dependences are qualitatively described within the framework of the self-consistent theory of Vollhardt and W\"olfle. The interference correction is therewith close in magnitude to the Drude conductivity so that the conductivity $\ensuremath{\sigma}$ becomes significantly less than ${e}^{2}/h.$ We conclude that the temperature and magnetic field dependences of the conductivity in the whole ${k}_{F}l$ range are due to changes of the quantum corrections.