Plasmon and coupled plasmon-phonon modes in graphene in the presence of inter-band excitation channels

TL;DR

This paper theoretically investigates plasmon and coupled plasmon-phonon modes in graphene, revealing multiple excitation channels and strong coupling effects that are crucial for designing plasmonic devices.

Contribution

It introduces a self-consistent field theory analysis showing multiple plasmon and coupled modes in graphene, emphasizing the importance of carrier-phonon interactions.

Findings

Two plasmon modes and four coupled plasmon-phonon modes can be excited.

Strong coupling between plasmon modes and optic phonons occurs at higher q and carrier density.

Carrier-phonon interaction is essential for understanding electronic excitations in graphene.

Abstract

Plasmon and coupled plasmon-phonon modes in graphene are investigated the-oretically within the diagrammatic self-consistent field theory. It shows that two plasmon modes and four coupled plasmon-phonon modes can be excited via intra-and inter-band transition channels. It is found that with increasing q and carrier density, the plasmon modes couple strongly with the optic-phonon modes in graphene. The coupled plasmon-phonon modes exhibit some interesting features which can be utilized to realize the plasmonic devices. Our results suggest that the carrier-phonon interaction should be considered to understand and explain the properties of elementary electronic excitations in graphene.