  A first-principles investigation of the electronic and quantum transport
properties of double-walled carbon nanotubes doped with nitrogen and boron
atoms is presented. Concentric nanotube sidewalls separated by the typical
graphitic van der Waals bond distance are found to strongly interact upon
incorporation of doping atoms in the hexagonal networks. The local perturbation
caused by the doping atoms extends over both shells due to a hybridization of
their electronic states, yielding a reduction of the backscattering efficiency
as compared with two independent single-walled nanotubes. A multi-scale
approach for the study of transport properties in micrometer-long double-walled
carbon nanotubes allows to demonstrate that transitions from the ballistic to
the localized regime can occur depending on the type of doping and the energy
of the charge carrier. These results shed light on the quantum mechanism by
which B and N doping represent an efficient method to create mobility gaps in
metallic concentric carbon nanotubes.
