ABSTRACT
We present interband magneto-absorption study for highly aligned and unbundled single-walled carbon nanotubes embedded in gelatine films under high magnetic fields up to 120 T. Absorption peaks originated from the second-subband gaps in semiconducting tubes and metallic tubes exhibit splitting by the application of magnetic fields in parallel to the alignment of tubes while not in perpendicular to it, which confirms a manifestation of the Aharonov-Bohm effect in the band structure of metallic tubes as well as semiconducting tubes. The amount of splitting is quantitatively consistent with theoretical expressions taking into account the Aharonov-Bohm effect for the semiconducting tubes. However, discrepancy between the experimental results and the theoretical predictions is found for the metallic tubes. Possible origins of the discrepancy are discussed.
