The impact of disorder on Dirac plasmon losses

TL;DR

This paper investigates how disorder affects the lifetime of Dirac plasmons in graphene, revealing that impurity scattering significantly shortens plasmon lifetimes compared to transport scattering times, aligning theory with experiments.

Contribution

The paper develops a minimal theoretical model for Dirac plasmon damping due to impurities and demonstrates its agreement with experimental observations.

Findings

Impurities cause significant plasmon damping in graphene.

Plasmon lifetime is governed by the imaginary part of the current-current response.

Theoretical damping rates match experimental data for realistic impurity concentrations.

Abstract

Recent scattering-type scanning near-field optical spectroscopy (s-SNOM) experiments on single-layer graphene have reported Dirac plasmon lifetimes that are substantially shorter than the dc transport scattering time \tau_{tr}. We highlight that the plasmon lifetime is fundamentally different from \tau_{tr} since it is controlled by the imaginary part of the current-current linear response function at finite momentum and frequency. We first present the minimal theory of the extrinsic lifetime of Dirac plasmons due to scattering against impurities. We then show that a very reasonable concentration of charged impurities yields a plasmon damping rate which is in good agreement with s-SNOM experimental results.