Effect of retardation on the frequency and linewidth of plasma resonances in a two-dimensional disk of electron gas

TL;DR

This paper provides a theoretical analysis of how electromagnetic retardation influences the frequency and damping of plasma resonances in a two-dimensional electron gas disk, revealing that retardation can reduce damping rates.

Contribution

It introduces a self-consistent model incorporating retardation effects to analyze plasma mode frequencies and linewidths in 2D electron gas disks, combining numerical and analytical methods.

Findings

Retardation affects the frequency and linewidth of plasma modes.

Net damping rate depends on radiative and collisional decay intermixture.

Retardation can reduce damping below collisional decay levels.

Abstract

We theoretically analyze dominant plasma modes in a two-dimensional disk of electron gas by calculating the absorption of an incident electromagnetic wave. The problem is solved in a self-consistent approximation, taking into account electromagnetic retardation effects. We use the Drude model to describe the conductivity of the system. The absorption spectrum exhibits a series of peaks corresponding to the excitation of plasma waves. The position and linewidth of the peaks designating, respectively, the frequency and damping rate of the plasma modes. We estimate the influence of retardation effects on the frequency and linewidth of the fundamental (dipole) and axisymmetric (quadrupole) plasma modes both numerically and analytically. We find the net damping rate of the modes to be dependent on not only the sum of the radiative and collisional decays but also their intermixture, even for small retardation. We show that the net damping rate can be noticeably less than that determined by collisions alone.