Unusual spin-polarized electron state in fullerene induced by carbon adatom defect

First-principles calculations show that a carbon adatom defect at the Def[5, 6] site on the surface of C60 can produce a more stable spin-polarized singlet electronic state instead of a magnetic triplet state. This is clearly different from the cases of graphene and nanotubes. The mechanism results from the electron population of the adatom, which produces antiferromagnetic coupling around the C60 cage and the adatom itself. Our calculations show the same phenomenon occurs in other IPR fullerenes, such as C70 and C80. These findings extend the understanding of the magnetic origin of pure carbon structures and are valuable for research related to the spin polarization of carbon systems.