Superconductivity in carbon nanotubes coupled to transition metal atoms

The electronic structures of zigzag and armchair single-walled carbon nanotubes interacting with a transitional-metal atomic nanowire of Ni have been determined. The Ni nanowire creates a large electron density of states (DOS) at the Fermi energy. The dependence of the enhanced DOS on the spin state and positioning of the transition metal wire (inside or outside the nanotube) is studied. Preliminary estimates of the electron-phonon interaction suggest that such systems may have a superconducting transition temperature of ∼ 10-50 K. The signs of superconductivity seen in "ropes" of nanotubes may also be related to the effect of intrinsic transition metal impurities.