Exciton Bose-Einstein Condensation in Double Walled Carbon Nanotubes
- PDF / 710,466 Bytes
- 6 Pages / 612 x 792 pts (letter) Page_size
- 21 Downloads / 341 Views
Exciton Bose-Einstein Condensation in Double Walled Carbon Nanotubes Igor V. Bondarev and Adrian Popescu Department of Math & Physics, North Carolina Central University, Durham, NC 27707, U.S.A. ABSTRACT We demonstrate theoretically the possibility for the Bose-Einstein condensation of excitons in properly selected double walled carbon nanotube structures. The condensation mechanism is enabled by the interaction of excitons residing on one tubule with the near-field generated by the plasmon mode of the other coaxial tubule, resulting in new hybridized bosonic quasiparticles called exciton-plasmons. We derive the dispersion relation for the exciton-plasmons, and calculate the exciton participation rate in the exciton-plasmon condensate. The requirements for forming the appropriate double walled carbon nanotube combinations capable of the optimum exciton-plasmon coupling regime needed to realize the condensation effect, as well as the possibility of experimental observation of the phenomenon, are discussed. INTRODUCTION Exciton Bose-Einstein condensates (BECs), coherent many-particle states of excitons with zero translational momentum, have received considerable attention since their first theoretical prediction in the 1900’s [1-6]. This has been motivated by fundamental as well as practical interest. Fundamental interest comes from the aspiration to understand the physical nature of coherent collective electron-hole excitations in low-dimensional semiconductors. Practical interest is prompted by the need to develop sustainable and efficient coherent light emission sources using the photoluminescence of the exciton Bose-Einstein condensate. Here we demonstrate theoretically the possibility for exciton BEC in a novel quasi-onedimensional (quasi-1D) system – a double walled semiconducting carbon nanotube (DWCN). Because of the peculiar quasi-1D character of single walled carbon nanotubes (SWCNs), both excitons and interband plasmons can coexist in the same energy range of the order of 1 eV in these structures [6-8]. The proposed condensation mechanism is enabled by the near-field coupling of excitons residing on one tubule with the interband plasmon mode of the same energy on the other coaxial tubule, to form new hybridized bosonic type excitations – exciton-plasmons. Possibilities for achieving BEC in 1D and 2D systems are theoretically demonstrated in the presence of an extra confinement potential [9,10]. We show that the strongly correlated excitonplasmon system in an appropriately chosen DWCN combination presents such a special case. We derive the analytic solutions for the coupled exciton-plasmon quasiparticle dispersion relation and give the selection rules for forming the DWCN system to exhibit the robust exciton-plasmon BEC phenomenon. We further present the calculated exciton participation rate in the excitonplasmon condensate and discuss the possibility for experimental observation of the exciton BEC. The effect we predict offers a testing ground for fundamentals of condensed matter physics in one dimension an
Data Loading...
