Nanotubes with chiral symmetry placed in a transverse electric field as a new type of superlattice

Electron motion in a helicoidal (chiral) nanotube is shown to correspond to a de Broglie wave propagating along a helicoidal line on the nanotube wall. This helical motion leads to periodicity of the electron potential energy in the presence of an electric field normal to the nanotube axis. The period of this potential is proportional to the nanotube radius and is greater than the interatomic distance in the nanotube. As a result, the behavior of an electron in helicoidal nanotubes subject to a transverse electric field is similar to that in a semiconductor superlattice. In particular, Bragg scattering of electrons from the long-range periodic potential results in the opening of gaps in the energy spectrum of the nanotube. Modification of the bandstructure raises the possibility of applying this effect to novel nanoelectronic devices.