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.