منابع مشابه
Kohn anomalies in graphene nanoribbons
The quantum corrections to the energies of the point optical phonon modes Kohn anomalies in graphene nanoribbons NRs are investigated. We show theoretically that the longitudinal optical LO modes undergo a Kohn anomaly effect, while the transverse optical TO modes do not. In relation to Raman spectroscopy, we show that the longitudinal optical modes are not Raman active near the zigzag edge, wh...
متن کاملChirality-induced dynamic kohn anomalies in graphene.
We develop a theory for the renormalization of the phonon energy dispersion in graphene due to the combined effects of both Coulomb and electron-phonon (e-ph) interactions. We obtain the renormalized phonon energy spectrum by an exact analytic derivation of the phonon self-energy, finding three distinct Kohn anomalies (KAs) at the phonon wave vector q=omega/v, 2k_{F}+/-omega/v for LO phonons an...
متن کاملKohn anomalies in superconductors.
I present the detailed behavior of phonon dispersion curves near momenta which span the electronic Fermi sea in a superconductor. I demonstrate that an anomaly, similar to the metallic Kohn anomaly, exists in a superconductor’s dispersion curves when the frequency of the phonon spanning the Fermi sea exceeds twice the superconducting energy gap. This anomaly occurs at approximately the same mom...
متن کاملKohn Anomalies in Graphite and Nanotubes
Atomic vibrations are partially screened by electrons. In a metal this screening can change rapidly for vibrations associated to certain points of the Brillouin zone, entirely determined by the shape of the Fermi surface. The consequent anomalous behaviour of the phonon dispersion is called Kohn anomaly. Graphite is a semimetal. Nanotubes can be metals or semiconductors. We demonstrate that two...
متن کاملInterfaces Within Graphene Nanoribbons
We study the conductance through two types of graphene nanostructures: nanoribbon junctions in which the width changes from wide to narrow, and curved nanoribbons. In the wide-narrow structures, substantial reflection occurs from the wide-narrow interface, in contrast to the behavior of the much studied electron gas waveguides. In the curved nanoribbons, the conductance is very sensitive to det...
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ژورنال
عنوان ژورنال: Physical Review B
سال: 2009
ISSN: 1098-0121,1550-235X
DOI: 10.1103/physrevb.80.155450