Nanometer-scale ferromagnet: Carbon nanotubes with finite length

We report first-principle total-energy elelctronic-structure calculations in the density functional theory performed for zigzag carbon nanotubes with finite length. We find that the electronic structure of the finite-length nanotubes exhibits certain magnetic ordering. Detailed analyses of energy levels and spin densities unequivocally reveal nature of the magnetic ordering which is associated with the peculiar edge-localized states of the graphite flakes. The magnetic ordering of the finite-length nanotube strongly depends on its radius and length.