High-Energy Limit of Massless Dirac Fermions in Multilayer Graphene using Magneto-Optical Transmission Spectroscopy

TL;DR

This study explores the high-energy behavior of electrons in multilayer graphene under strong magnetic fields, revealing deviations from ideal Dirac behavior at energies above 500 meV, consistent with advanced theoretical models.

Contribution

It provides experimental evidence of high-energy deviations from Dirac linearity in multilayer graphene, incorporating effects like trigonal warping and higher-order band corrections.

Findings

Deviation from linear Dirac dispersion at >500 meV

40 meV deviation at 1.25 eV energy

No observable electron-hole asymmetry

Abstract

We have investigated the absorption spectrum of multilayer graphene in high magnetic fields. The low energy part of the spectrum of electrons in graphene is well described by the relativistic Dirac equation with a linear dispersion relation. However, at higher energies (>500 meV) a deviation from the ideal behavior of Dirac particles is observed. At an energy of 1.25 eV, the deviation from linearity is 40 meV. This result is in good agreement with the theoretical model, which includes trigonal warping of the Fermi surface and higher-order band corrections. Polarization-resolved measurements show no observable electron-hole asymmetry.