Plasmon electron-hole resonance in epitaxial graphene

TL;DR

This study investigates the quasiparticle dynamics of sheet plasmons in epitaxial graphene on SiC, revealing how temperature, defects, multilayers, and carrier density influence plasmon behavior and electron-hole resonances.

Contribution

It provides a systematic analysis of plasmon-electron-hole resonances in epitaxial graphene, demonstrating that plasmon dispersion aligns with a nearly free electron gas model despite electronic correlations.

Findings

Inter-band loss channel causes upward plasmon dispersion shift

Dip in loss peak width indicates electron-hole resonance

Plasmon behavior consistent with nearly free electron gas model

Abstract

The quasiparticle dynamics of the sheet plasmons in epitaxially grown graphene layers on SiC(0001) have been studied systematically as a function of temperature, intrinsic defects, influence of multilayers and carrier density. The opening of the inter-band loss channel appears as a characteristic upward shift in the plasmon dispersion and a dip in the width of the loss peak, which is explained as a resonance effect in the formation of electron-hole pairs. Despite the existence of strong electronic correlations, the plasmon dispersion can be quantitatively described within the framework of a nearly free electron gas.