Screening in coupled low-dimensional systems: an effective polarizability picture

TL;DR

This paper introduces an effective polarizability approach to model screening effects in coupled low-dimensional systems, simplifying the influence of environment on individual objects using a multi-component RPA framework.

Contribution

It presents a novel effective polarizability concept for coupled low-dimensional systems, demonstrated analytically with a two-layer 2DEG model, linking it to the dielectric function and plasmon excitations.

Findings

Effective polarizability equals the dielectric function of the system.

Mutual modulation of Friedel oscillations observed.

Screening limit set by metallic layers discussed.

Abstract

The screening of an individual low-dimensional object can be strongly influenced by the objects nearby. We propose that such environment's influence can be absorbed into an effective polarizability, instead of its intrinsic polarizability. Using a toy system consists of two spatially separated 2DEG layers gas an example, this picture is analytically deduced via a multi-component RPA theoretical method. We show that the resultant effective polarizability of backside layer is just the dielectric function describing the system's collective plasmon excitations. Furthermore, several interesting topics are discussed, e.g. the mutual modulation of Friedel oscillation, the ultimate screening limit imposed by metal layer, smoothing potential inhomogeneity in back screening configuration.