Toroidal carbon nanotubes can serve as hosts for encapsulated loops of atomic metal wires. Such composite structures have been analyzed using density functional theory for a semiconducting C120 torus encapsulating chains of Fe, Au and Cu atoms. The sheathed metal necklaces form a zigzag structure and drops the HOMO/LUMO bandgap to less than 0.1 eV. The iron composite is ferromagnetic with a magnetic moment essentially the same as that of bcc iron. The azimuthal symmetry of these toroidal composites suggests that they may offer novel elecromagnetic properties not associated with straight, metal-encapsulated carbon nanotubes.
@article{arxiv.1009.0442,
title = {Toroidal Carbon Nanotubes with Encapsulated Atomic Metal Loops},
author = {Mark T. Lusk and Nathaniel Hamm},
journal= {arXiv preprint arXiv:1009.0442},
year = {2010}
}