Intrinsic lifetime of Dirac plasmons in graphene

TL;DR

This paper calculates the intrinsic lifetime of Dirac plasmons in doped graphene, revealing how electron-electron interactions and pseudospin suppress plasmon damping in disorder-free conditions.

Contribution

It introduces a method to analyze intrinsic plasmon damping in graphene considering electron-electron interactions beyond RPA, highlighting the role of pseudospin.

Findings

Graphene's pseudospin suppresses intrinsic plasmon losses.

Intrinsic damping occurs even in disorder-free samples.

Calculated plasmon lifetime relates to dynamical conductivity below absorption threshold.

Abstract

Dirac plasmons in a doped graphene sheet have recently been shown to enable confinement of light to ultrasmall volumes. In this work we calculate the intrinsic lifetime of a Dirac plasmon in a doped graphene sheet by analyzing the role of electron-electron interactions beyond the random phase approximation. The damping mechanism at work is intrinsic since it operates also in disorder-free samples and in the absence of lattice vibrations. We demonstrate that graphene's sublattice-pseudospin degree of freedom suppresses intrinsic plasmon losses with respect to those that occur in ordinary two-dimensional electron liquids. We relate our findings to a microscopic calculation of the homogeneous dynamical conductivity at energies below the single-particle absorption threshold.