Excitations from Filled Landau Levels in Graphene

TL;DR

This paper investigates the behavior of single particle-hole excitations in graphene under strong magnetic fields, revealing many-body effects and exciton dispersion characteristics influenced by spin and valley filling.

Contribution

It provides a detailed analysis of excitations in graphene considering Coulomb interactions, including the impact of multiple filled Landau levels and valley effects.

Findings

Strong many-body corrections affect excitation spectra.

Exciton dispersion is sensitive to filled spin and valley sublevels.

Potential observability in inelastic light scattering and optical absorption.

Abstract

We consider graphene in a strong perpendicular magnetic field at zero temperature with an integral number of filled Landau levels and study the dispersion of single particle-hole excitations. We first analyze the two-body problem of a single Dirac electron and hole in a magnetic field interacting via Coulomb forces. We then turn to the many-body problem, where particle-hole symmetry and the existence of two valleys lead to a number of effects peculiar to graphene. We find that the coupling together of a large number of low-lying excitations leads to strong many-body corrections, which could be observed in inelastic light scattering or optical absorption. We also discuss in detail how the appearance of different branches in the exciton dispersion is sensitive to the number of filled spin and valley sublevels.