Temperature-dependent Plasmons and Their Damping Rates for Graphene with a Finite Energy Bandgap

TL;DR

This paper derives analytical and numerical expressions for temperature-dependent plasmon dispersion and damping in gapped graphene, revealing that a finite energy gap reduces damping rates and affects plasmon behavior.

Contribution

It provides the first closed-form analytic expressions for finite-temperature plasmon dispersion in gapped graphene within the high temperature and long-wavelength limits.

Findings

Damping rate decreases with a finite energy gap.

Plasmon frequency and damping are linear in wave vector for substrate-coupled graphene.

Analytic expressions are applicable to other buckled honeycomb structures.

Abstract

We obtained numerical and closed-form analytic expressions for finite-temperature plasmon dispersion relations for intrinsic graphene in the presence of a finite energy gap in the energy spectrum. The calculations were carried out using the random-phase approximation. The analytic results have been derived in the high temperature regime and long-wavelength limit. We have found that the plasmon damping rate decreases in the presence of a band gap. Our method of calculation could also be applied to silicene and other buckled honeycomb lattice structures. The finite-temperature plasmon dispersion relations are presented when a single graphene layer is Coulomb coupled to a semi infinite conductor. Both cases of gapless and gapped monolayer graphene have been investigated when a thick substrate is in their proximity. Both the plasmon excitation frequency and damping rate are linear functions of the in-plane wave vector in the long wavelength limit when a monolayer interacts with a conducting substrate which is not the case for free-standing pristine or gapped graphene.