Coherent electron backscattering interference in non-uniform disordered systems

We study the coherent electron backscattering interference in the presence of electron dephasing in 2D/3D non-uniform (NU) disordered systems, within our virtual electron trap scattering (VETS) model, where the dephasing rate 1/tau(phi) is taken to be due to the inelastic electron-electron or electron-phonon scattering. A possible saturation mechanism of apparent electronic dephasing is examined. The system considered is composed of two kinds of subsystems, namely, L-islands and H-region with contrasting diffusion constants, of which the L-islands (of low diffusion constant) act as virtual electron traps randomly dispersed in the percolating H-background (of high diffusion constant). The physics of VETS model is characterized by the two importantd well times, tau(f) and tau(b), with tau(f)/tau(b) being the mean duration for which an electron wanders in the H-region/L-island before it leaves the region, respectively. In order to make connection with experiments, we introduce the notion of an effective system of uniform (U) disorder with a dephasing time tau((effective))(phi), which simulates in the aspect of backscattering the NU system being studied. The effective dephasing time tau((effective))(phi) thus introduced is a function of tau(phi), and the function, tau((effective))(phi)(tau(phi)), is derived and examined. If tau(b) >> tau(f), an interesting phenomenon occurs in the range of temperature (T) where the true dephasing time tau(phi)(T) lies between tau(f) and tau(b), i.e., tau(f) < tau(phi)(T) < tau(b). In this case, we obtain tau((effective))(phi)(tau(phi)) approximate to tau(f), which is insensitive to the variation in tau(phi) (or T) and shows the signature of tau((effective))(phi) saturation. However, at the further lowered temperature where tau(phi)(T) >= tau(b), tau((effective))(phi) rises up sharply without being saturated. (C) 2011 Elsevier B.V. All rights reserved.