Giant Suppression of the Drude Conductivity Due to Quantum Interference in the Disordered Two-dimensional System GaAs Inx Ga1-x As GaAs

Abstract

Temperature and magnetic-field dependences of the conductivity in heavily doped, strongly disordered two-dimensional quantum well structures GaAs Inx Ga1-x As GaAs are investigated within wide conductivity and temperature ranges. The role of the interference in electron transport is studied in the regimes where the phase breaking length L crosses over the localization length ξ∼l exp (π kF l 2) with decreasing temperature, where kF and l are the Fermi quasimomentum and mean free path, respectively. It is shown that all the experimental data can be understood within a simple model of the conductivity over delocalized states. This model differs from the conventional model of weak localization developed for kF l 1 and L ξ in one respect: the value of the quantum interference contribution to the conductivity is restricted not only by the phase breaking length L but also by the localization length ξ. In this approach, it is the quantity (τ*) -1 = τ -1 + τξ -1, rather than τ -1 [where τ T-1 is the dephasing time and τξ ∼τ exp (π kF l)], that governs temperature and magnetic-field dependences of the conductivity over the wide range of temperature and disorder strength down to the conductivity of order 10-2 e2 h. © 2007 The American Physical Society.