Quasi-localization and quasi-mobility edge for light atoms mixed with heavy ones

TL;DR

This paper investigates how light atoms mixed with heavy atoms exhibit a crossover from fast to slow diffusion in 3D and a transition between weak and strong localization in 2D, influenced by dephasing and scatterer dynamics.

Contribution

It introduces the concepts of quasi-localization and quasi-mobility edge in mixed atomic systems, analyzing the effects of scatterer motion on atom diffusion and localization.

Findings

Existence of a crossover energy region in 3D separating fast and slow diffusion states.

Identification of a transition between weak and strong localization in 2D based on dephasing length.

Heavy atom motion influences the localization properties of light atoms.

Abstract

A mixture of light and heavy atoms is considered. We study the kinetics of the light atoms, scattered by the heavy ones, the latter undergoing slow diffusive motion. In three-dimensional space we claim the existence of a crossover region (in energy), which separates the states of the light atoms with fast diffusion and the states with slow diffusion; the latter is determined by the dephasing time. For the two dimensional case we have a transition between weak localization, observed when the dephasing length is less than the localization length (calculated for static scatterers), and strong localization observed in the opposite case.