High-conducting magnetic nanowires obtained from uniform titanium-covered carbon nanotubes

We have shown that a semiconducting single-wall carbon nanotube ~SWNT! can be covered uniformly by titanium atoms and form a complex but regular atomic structure. The circular cross section changes to a squarelike form, and the system becomes metallic with high state density at the Fermi level and with high quantum ballistic conductance. Metallicity is induced not only by the metal-metal coupling, but also by the band-gap closing of SWNT’s at the corners of the square. Even more interesting is that uniform titaniumcovered tubes have magnetic ground state with significant net magnetic moment. Our results have been obtained by the first-principles pseudopotential plane-wave calculations within the density-functional theory.