High field magneto-optical spectroscopy of highly aligned individual and ensemble single-walled carbon nanotubes

J. Shaver, A. Srivastava, J. Kono, S. A. Crooker, H. Htoon, V. I. Klimov, J. A. Fagan, E. K. Hobbie, N. Ubrig, O. Portugall, V. Perebeinos, Ph Avouris

Research output: Contribution to journalArticle

Abstract

The tubular nature of single-walled carbon nanotube (SWCNT) crystals allows them to exhibit non-intuitive quantum phenomena when threaded by a magnetic flux, which breaks the time reversal symmetry and adds an Aharonov-Bohm phase to the circumferential boundary conditions on the electronic wave function. We demonstrate that such a symmetry-breaking magnetic field can dramatically "brighten" an optically-inactive, or dark, exciton state at low temperature. This phenomenon, magnetic brightening, can be understood as a consequence of interplay between the strong intervalley Coulomb mixing and field-induced lifting of valley degeneracy. Most recently, we made the direct observation of the dark excitonic state in individual SWCNTs using low-temperature micro-photoluminescence (PL) and and verified the importance of a parallel, tube-threading magentic field with ensemble spectroscopy. For micro-PL, a magnetic field up to 5 T, applied along the nanotube axis, brightened the dark state, leading to the emergence of a new emission peak. The peak rapidly grew in intensity with increasing field at the expense of the originally-dominant bright exciton peak and finally became dominant at fields > 3 T. The directly measured dark-bright splitting values were 1-4 meV for tube diameters 1.0-1.3 nm. For ensemble PL, we used fields up to 55 T in two collection geometries to demonstrate the importance of the tube-threading component. These experiments have provided one of the most critical tests for recently-proposed theories of 1-D excitons taking into account the strong 1-D Coulomb interactions and unique band structure on an equal footing.

Original languageEnglish
Pages (from-to)2667-2675
Number of pages9
JournalInternational Journal of Modern Physics B
Volume23
Issue number12-13
Publication statusPublished - May 20 2009

Keywords

  • Aharonov-Bohm Phase
  • Carbon Nanotubes
  • Excitons
  • One Dimensionality

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Condensed Matter Physics

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    Shaver, J., Srivastava, A., Kono, J., Crooker, S. A., Htoon, H., Klimov, V. I., Fagan, J. A., Hobbie, E. K., Ubrig, N., Portugall, O., Perebeinos, V., & Avouris, P. (2009). High field magneto-optical spectroscopy of highly aligned individual and ensemble single-walled carbon nanotubes. International Journal of Modern Physics B, 23(12-13), 2667-2675.