Low-energy electronic properties of finite double-walled carbon nanotubes under external fields

Using the 2 p_z tight-binding model, we investigated the electronic properties of finite double-walled carbon nanotubes (DWCNTs) under static electric and magnetic fields. It was found that for low-energy electronic structures, their energy levels, density of states and energy gap are obviously affected by symmetric configurations as well as electric and magnetic fields. The intertube atomic interactions remarkably change the state energies, modulate the energy gap, and break the state symmetry about the Fermi level. Moreover, both electric and magnetic fields can destroy the degeneracy and modulate the above-mentioned electronic properties. The magnetic fields with various directions also induce variation of electronic structure. As the magnitude of electric fields perpendicular to the tube axis increases, more energy states gather around the Fermi energy, which, as a result, causes a complicated variation of energy gap.