Colossal Paramagnetic Moments in Metallic Carbon Nanotori

Carbon nanostructures with unusually large paramagnetic moments have been discovered in a theoretical study of the electronic and magnetic properties of carbon nanotubes bent into toroids. Specifically, nanotori formed from metallic nanotubes with λ_F = 3T, where λ_F is the Fermi wavelength and T the translation vector of the nanotube, exhibit giant paramagnetic moments at selected radii (“magic radii”), while the ones with λ_F = T are paramagnetic at any radius. The large paramagnetic moment is due to the interplay between the toroidal geometry and the ballistic motion of the π electrons in the metallic nanotube.