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

The density-of-states (DOS) near Fermi level of a single-wall carbon nanotube is studied in the presence of a magnetic field (B) parallel to the nanotube 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-field-induced metal-insulator transition is indicated in the variation of the band gap and the DOS. Zeeman effect on the band gap and the DOS is obvious from the derived expressions. These results may be observed by scanning tunneling spectroscopy measurements.