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Phys. Rev. B 78, 081402(R) (2008) [4 pages]

Magneto-optical spectroscopy of highly aligned carbon nanotubes: Identifying the role of threading magnetic flux

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J. Shaver1, S. A. Crooker2, J. A. Fagan3, E. K. Hobbie3, N. Ubrig4, O. Portugall4, V. Perebeinos5, Ph. Avouris5, and J. Kono1,*
1Department of Electrical and Computer Engineering, Rice University, Houston, Texas 77005, USA
2National High Magnetic Field Laboratory, Los Alamos, New Mexico 87545, USA
3National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
4Laboratoire National des Champs Magnétiques Pulsés, 31400 Toulouse, France
5IBM Research Division, T. J. Watson Research Center, Yorktown Heights, New York 10598, USA

Received 3 June 2008; published 4 August 2008

We have investigated excitons in highly aligned single-walled carbon nanotubes (SWCNTs) through optical spectroscopy at low temperatures down to 1.5 K and high magnetic fields (B) up to 55 T. SWCNT/polyacrylic acid films were stretched, giving SWCNTs that are highly aligned along the direction of stretch (n̂). Utilizing two well-defined measurement geometries, n̂∥B and n̂⊥B, we provide unambiguous evidence that the photoluminescence energy and intensity are only sensitive to the B-component parallel to the tube axis. A theoretical model of one-dimensional magnetoexcitons, based on exchange-split “bright” and “dark” exciton bands with Aharonov-Bohm-phase-dependent energies, masses, and oscillator strengths, successfully reproduces our observations and allows determination of the splitting between the two bands as ∼4.8 meV for (6,5) SWCNTs.

© 2008 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevB.78.081402
DOI:
10.1103/PhysRevB.78.081402
PACS:
78.67.Ch, 71.35.Ji, 78.55.−m

*kono@rice.edu

 
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