In this talk, one question arising in the physics of nanotube excitons is addressed: what is the shape of the excitation for a finite size SWCNT object? Since a whole SWCNT is sub-diffraction scale object, one may expect something similar to Hertz dipole, modified for a semiconductor material (as opposed to metal). To the best of our knowledge, such a solution was not known, thus a theory shedding light on the distribution of current of a nanotube excitonic emitter has been developed.
While in our earlier work we considered localization of a free excitonic wave (aka binding) on a single charged impurity[1], in this talk we assume localization effects due to SWCNT end reflections. Unlike many of earlier excitonic works we take this into account via a self-consistent response of the whole nanotube antenna. Unexpectedly, even for a charge neutral SWCNT system, plasmonic resonances were found to develop on top of the excitonic spectral response[2]. We demonstrate that these plasmonic features are robust and should be detectable in near-field experiments.
[1] BO. Tayo, SV. Rotkin, “Charge impurity as a localization center for singlet excitons in single-wall nanotubes”, Phys. Rev. B 86, 125431 (2012).
[2] B. Sofka, SV. Rotkin, “Nanotube exciton-antenna polaritons”, in preparation.
This research is supported by the NSF ECCS-1509786.
Fig. 1. Spectral current density distribution for an excitonic SWCNT emitter: 1d-current density is plotted vs. axial coordinate of a 50 nm long nanotube and vs. the frequency of excitation (in energy units).