Conductance of carbon nanotubes in a transverse electric field and an arbitrary magnetic field.

The electronic and transport properties of carbon nanotubes subject to the influences of a transverse electric field and an arbitrary magnetic field are studied by the tight-binding model. The external fields would modify the energy dispersions, destroy the state degeneracy, change the symmetry characteristics, alter the energy gap, modulate the electron effective mass, and create extra band-edge states. The energy gap and the electron effective mass exhibit a rich dependence on the field strength, the magnetic field direction, and the types of carbon nanotubes. A semiconductor-metal transition would be allowed for certain field strengths and magnetic field directions. The variations of energy dispersions with the external fields will also be reflected in the conductance. Special features of the conductance, such as single-shoulder, multi-shoulder, and spike structures, are predicted.