Influence of Landau level mixing on the properties of elementary excitations in graphene in strong magnetic field

TL;DR

This paper investigates how Landau level mixing, influenced by Coulomb interactions and dielectric environment, significantly alters the dispersion relations of magnetoexcitons and magnetoplasmons in graphene under strong magnetic fields.

Contribution

It provides a detailed analysis of Landau level mixing effects on elementary excitations in graphene, highlighting deviations from the lowest Landau level approximation.

Findings

Landau level mixing causes substantial changes in excitation dispersion laws.

Dielectric environment strongly influences the extent of Landau level mixing.

Significant deviations occur in magnetoexciton and magnetoplasmon properties at low dielectric screening.

Abstract

Massless Dirac electrons in graphene fill Landau levels with energies scaled as square roots of their numbers. Coulomb interaction between electrons leads to mixing of different Landau levels. The relative strength of this interaction depends only on dielectric susceptibility of surrounding medium and can be large in suspended graphene. We consider influence of Landau level mixing on the properties of magnetoexcitons and magnetoplasmons - elementary electron-hole excitations in graphene in quantizing magnetic field. We show that, at small enough background dielectric screening, the mixing leads to very essential change of magnetoexciton and magnetoplasmon dispersion laws in comparison with the lowest Landau level approximation.