Electronic structure of graphene beyond the linear dispersion regime

TL;DR

This paper derives analytical expressions for graphene's electronic Green function valid over a broad energy spectrum, enabling better understanding of high-energy physical properties like magnetic interactions.

Contribution

It introduces a set of closed-form Green function expressions for graphene beyond the linear dispersion regime, expanding analytical tools for high-energy electronic properties.

Findings

Green function expressions valid across extensive energy ranges

Enhanced analysis of high-energy physical phenomena in graphene

Application to magnetic (RKKY) interactions

Abstract

Among the many interesting features displayed by graphene, one of the most attractive is the simplicity with which its electronic structure can be described. The study of its physical properties is significantly simplified by the linear dispersion relation of electrons in a narrow range around the Fermi level. Unfortunately, the mathematical simplicity of graphene electrons is only limited to this narrow energy region and is useless when dealing with problems that involve energies outside the linear dispersion part of the spectrum. In this letter we remedy this limitation by deriving a set of closed-form analytical expressions for the real-space single-electron Green function of graphene which are valid across an enormous fraction of the energy spectrum. By extending to a wider energy range the simplicity with which graphene electrons are described, it is now possible to derive more mathematically transparent and insightful expressions for a number of physical properties that involve higher energy scales. The power of this new formalism is illustrated in the case of the magnetic (RKKY) interaction in graphene.