Zeeman effect on the electronic spectral properties of carbon nanotubes inan axial magnetic field

The density-of-states (DOS) near Fermi level of a single-wall carbon nanotu be is studied in the presence of a magnetic field (B) parallel to the nanot ube axis. Expressions of the band gap and the DOS near the Fermi level are derived in the case of with and without spin-B interaction. A magnetic-fiel d-induced metal-insulator transition is indicated in the variation of the b and gap and the DOS. Zeeman effect on the band gap and the DOS is obvious f rom the derived expressions. These results may be observed by scanning tunn eling spectroscopy measurements.