Year: 2015
Type: article
Abstract: In this paper we investigate the excitations in a single graphene layer and in a single-walled carbon nanotube, i.e. the spectrum of magnetic excitations is calculated. In the absence of interactions in these systems there is a unique gap in the electron-hole continuum. We show that in the presence of Coulomb correlations bound states, magnons, appear in this forbidden region. The Coulomb interaction is examined in the context of the Pariser-Parr-Pople (PPP) model which takes into account the long-range nature of the interaction. The energy of the new bound states depends on the strength of the Coulomb forces. The calculations are performed for arbitrary electron-hole ( e - h ) momentum q . In the end, this work finally settles the discussion sabout the existence of triplet excitations in graphene which has been lasting for a decade in the literature.
Source: Europhysics Letters (EPL)
Authors: V. Posvyanskiy, L. Arnarson, P. Hedegård
Institution: University of Copenhagen
Language: English
Subfield: Materials Chemistry
Field: Materials Science
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W2038093088