The effects of a transverse field and a single defect upon the conductance of an achiral carbon nanotube were investigated. It was found that armchair nanotubes under a transverse field were always metallic, and field-induced metal-semiconductor and semiconductor-metal transitions were shown for zig-zag nanotubes. Metal-semiconductor transition fields were independent of the defect, while semiconductor-metal transition fields were sensitive to the field-defect azimuth, defect type and strength. The field-defect azimuth was a new degree of freedom and could be used to tailor and control the electronic behavior.

Transverse-Field and Defect-Azimuth Effects in Achiral Carbon Nanotubes. J.L.Zhu, H.F.Song, X.Hu: Journal of Physics - Condensed Matter, 2005, 17[29], 4629-36