Inter-valley plasmons in graphene

TL;DR

This paper investigates new low-frequency inter-valley plasmon modes in graphene arising from electron transitions between Dirac cones, considering the full tight-binding dispersion and local field effects.

Contribution

It introduces the concept of inter-valley plasmons in graphene, accounting for the complete dispersion relation and local field effects, which were not considered in previous studies.

Findings

Discovery of low-frequency inter-valley plasmon modes near Brillouin zone corners

These modes have a linear spectrum and are related to Dirac cone transitions

Enhanced understanding of graphene's plasmonic properties in the full band structure

Abstract

The spectrum of two-dimensional (2D) plasma waves in graphene has been recently studied in the Dirac fermion model. We take into account the whole dispersion relation for graphene electrons in the tight binding approximation and the local field effects in the electrodynamic response. Near the wavevectors close to the corners of the hexagon-shaped Brillouin zone we found new low-frequency 2D plasmon modes with a linear spectrum. These "inter-valley" plasmon modes are related to the transitions between the two nearest Dirac cones.