Magneto-optical studies of single-wall carbon nanotubes

We report a detailed study of the magnetophotoluminescence of single-wall carbon nanotubes at various temperatures in fields up to 58 T. We give direct experimental evidence of the diameter dependence of the Aharanov-Bohm phase-induced band gap shifts. Large increases in intensity are produced by the magnetic field at low temperatures which are also significantly chiral index [(n,m)] dependent. These increases are attributed to the magnetic field induced mixing of the wave functions of the exciton states. A study of the emission from nanotubes aligned perpendicular to the applied magnetic field shows even larger field-induced photoluminescence intensity enhancements and unexpectedly large redshifts in band gap energies, not predicted theoretically.