Dephasing and Anderson localization in topologically disordered systems.

Abstract

A simple theory is developed to describe the interplay between Anderson localization and dephasing mechanisms (such as inelastic electron- or exciton-phonon coupling), within the framework of a tight-binding model of spatially disordered systems. Self-consistency is enforced by demanding that only the most probable value of the imaginary part of the site self-energy be self-consistently determined. Dephasing interactions are characterized simply by an energy-independent dephasing rate. When the dephasing rate vanishes the pure localization problem may be examined as the transition is approached from either the localized or the extended regimes; mobility-edge trajectories may thereby be located. In the limit of rapid dephasing the theory correlates with the usual master-equation treatments of incoherent transport. For sufficiently large disorder a nonmonotonic but continuous crossover from coherent to incoherent transport is in general predicted. The problem of Mooij correlation, viewed as a weak-delocalization phenomenon, is also examined: it is suggested that the correlation is not universal as has frequently been supposed.