It has long been established that by filling carbon nanotubes or coating on their surfaces with transition metals, one-dimensional hybrid nanostructures can be synthesized. We found through ab initio calculations that such transition-metal/nanotube hybrid structures exhibit substantial magnetism. In particular, cobalt atoms packed inside a variety of carbon nanotubes offer strong spin polarization at the Fermi level as well as considerable magnetic moments. The results point to a new and promising approach that uses such metal-filled carbon nanotubes as devices for spin-polarized transport and to potential applications in the emerging field of spintronics.

• Received 24 October 2002

DOI:https://doi.org/10.1103/PhysRevLett.90.257203