Dirac electronic states in graphene systems: Optical spectroscopy studies

TL;DR

This paper reviews optical spectroscopy studies of various graphene forms and graphite, emphasizing the relativistic-like behavior of quasi particles known as Dirac fermions, and discusses their electronic properties.

Contribution

It provides a comprehensive overview of optical spectroscopy findings on Dirac states across multiple carbon allotropes, highlighting their relativistic electronic behavior.

Findings

Confirmation of Dirac fermions in graphene and graphite

Observation of relativistic-like optical responses

Comparison of electronic properties across different carbon allotropes

Abstract

Electronic properties of two-dimensional allotropes of carbon, such as graphene and its bilayer, multi-layer epitaxial graphene, few-layer Bernal-stacked graphene, as well as of three-dimensional bulk graphite are reviewed from the viewpoint of recent optical spectroscopy studies. Attention is focused on relativistic-like character of quasi particles in these systems, which are referred to as massless or massive Dirac fermions.