Dresden 2009 – scientific programme
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HL: Fachverband Halbleiterphysik
HL 48: Poster 2
HL 48.15: Poster
Thursday, March 26, 2009, 15:00–17:30, P2
Excitonic Rayleigh scattering spectra for metallic single-walled carbon nanotubes — •Ermin Malic1, Stephanie Reich2, and Andreas Knorr1 — 1Institut für Theoretische Physik, Technische Universität Berlin — 2Fachbereich Physik, Freie Universität Berlin
We present a microscopic calculation of the excitonic Rayleigh scattering cross section for metallic single-walled carbon nanotubes. Our approach combines the density matrix formalism including the Coulomb and electron-light interaction with the tight-binding approximation. We go beyond the two-band picture taking all nanotube subband contributions into account.
Due to the strong screening in metallic tubes, the Coulomb interaction is weak resulting in smaller excitonic binding energies (around 100 meV) in comparison to semiconducting nanotubes with a similar diameter. In agreement with experiments, the Rayleigh spectra of metallic nanotubes are shown to have a double-peaked structure caused by the triangular equi-energy contour around the K point (trigonal warping effect). Furthermore, the non-resonant contributions of the optical susceptibility account for the asymmetry of Rayleigh peaks towards lower energies.