Localized Collective Excitations in Doped Graphene in Strong Magnetic Fields

TL;DR

This paper investigates localized collective excitations in doped graphene under strong magnetic fields, revealing impurity-induced modes, duality in spectra, and implications for magneto-optical transitions at various filling factors.

Contribution

It introduces the analysis of impurity-induced localized collective modes and duality in spectra in doped graphene in strong magnetic fields, expanding understanding of magnetoplasmon behavior.

Findings

Localized collective modes split off from the continuum.

Impurity absorption peaks appear above and below cyclotron resonance.

Duality between D+ and A- impurity spectra due to electron-hole symmetry.

Abstract

We consider collective excitations in graphene with filled Landau levels (LL's) in the presence of an external potential due to a single charged donor D+ or acceptor A- impurity. We show that localized collective modes split off the magnetoplasmon continuum and, in addition, quasibound states are formed within the continuum. A study of the evolution of the strengths and energies of magneto-optical transitions is performed for integer filling factors nu = 1, 2, 3, 4 of the lowest LL. We predict impurity absorption peaks above as well as below the cyclotron resonance. We show that the single particle electron-hole symmetry of graphene leads to a duality between the spectra of collective modes for the D+ and A-. The duality shows up as a set of the D+ and A- magneto-absorption peaks having same energies, but active in different circular polarizations.