Electron-vibron coupling in suspended carbon nanotube quantum dots
Mariani, Eros; von Oppen, Felix
Date: 2 October 2009
Article
Journal
Physical Review B - Condensed Matter and Materials Physics
Publisher
American Physical Society
Publisher DOI
Abstract
Motivated by recent experiments, we investigate the electron-vibron coupling in suspended carbon nanotube quantum dots, starting with the electron-phonon coupling of the underlying graphene layer. We show that the coupling strength depends sensitively on the type of vibron and is strongly sample dependent. The coupling strength becomes ...
Motivated by recent experiments, we investigate the electron-vibron coupling in suspended carbon nanotube quantum dots, starting with the electron-phonon coupling of the underlying graphene layer. We show that the coupling strength depends sensitively on the type of vibron and is strongly sample dependent. The coupling strength becomes particularly strong when inhomogeneity-induced electronic quantum dots are located near regions where the vibronic mode is associated with large strain. Specifically, we find that the longitudinal stretching mode and the radial breathing mode are coupled via the strong deformation potential, while twist modes couple more weakly via a mechanism involving modulation of the electronic hopping amplitudes between carbon sites. A special case are bending modes: for symmetry reasons, their coupling is only quadratic in the vibron coordinate. Our results can explain recent experiments on suspended carbon nanotube quantum dots, which exhibit vibrational sidebands accompanied by the Franck-Condon blockade with strong electronvibron coupling.
Physics and Astronomy
Faculty of Environment, Science and Economy
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