Magnetoplasmons bound to short-range impurities in graphene: Symmetries and optics

TL;DR

This paper investigates how short-range impurities in graphene under a magnetic field affect localized magnetoplasmon excitations, revealing symmetries and optical properties across various conditions.

Contribution

It introduces a classification scheme for impurity-induced magnetoplasmons in graphene and analyzes their energies and optical responses considering symmetries and different impurity parameters.

Findings

Localized magnetoplasmon energies depend on impurity strength and filling factor.

Symmetries relate excitation energies and optical strengths across different impurity and polarization configurations.

Impurity-induced states exhibit characteristic optical signatures that can be used for identification.

Abstract

We consider a graphene sheet in the presence of a strong perpendicular magnetic field with a single short-range delta-impurity situated at one of the carbon sites. We study the neutral inter-Landau level collective excitations, magnetoplasmons, which become localized on the impurity. Some of these excitations involve a pseudospin flip (intervalley transitions), since the impurity can scatter electrons between the two valleys. We propose a classification of states of the excitations in graphene and introduce the appropriate quantum numbers. The energies and optical strengths of collective excitations are calculated for a range of integer filling factors and impurity strengths. We establish a set of symmetries matching the energies and absorption strengths of collective excitations for different sublattice locations of the impurity, filling factors, circular light polarizations and signs of the impurity potential.