Surface plasmon in 2D Anderson insulator with interactions

TL;DR

This paper investigates how Coulomb interactions influence the surface plasmon propagation in a 2D Anderson insulator, revealing conditions under which plasmon propagation becomes feasible due to conductivity changes.

Contribution

It demonstrates that Coulomb correlations can induce a sign change in the imaginary part of conductivity, enabling surface plasmon propagation in a localized 2D system.

Findings

Coulomb interactions enhance low-frequency conductivity.

Sign change in the imaginary part of conductivity occurs within a specific frequency range.

Surface plasmon propagation becomes possible in a localized 2D system due to these effects.

Abstract

We study the effect of interactions on the zero-temperature a.c. conductivity of 2D Anderson insulator at low frequencies. We show that the enhancement of the real part of conductivity due to the Coulomb correlations in the occupation numbers of localized states results in the change of the sign of imaginary part within a certain frequency range. As a result, the propagation of a surface plasmon in a localized system becomes possible. We analize the dispersion law of the plasmon for the two cases: unscreened Coulomb interactions and the interactions screened by a gate electrode spaced by some distance from the electron plane.