“…18,19,20,21,22,23,24 Defects of different complexity and topology were considered: carbon vacancies in graphite, 18,19 carbon adatoms on the graphene layer, 20 vacancies in the fullerene cages 21 , partially opened intermediate fullerene cage structures with the zigzag-type edge, 22 the carbon tetrapods with negative Gaussian curvature 23 , and the special open-cage defect structure with the hydrogen atom bonded chemically to one of defect carbon atoms. 24 It is yet unclear whether these defects are present in real fullerene samples (see, however, Ref. 25, where atomic-scale defects were observed in graphene layers) and whether the spin-spin interaction is ferromagnetic and strong enough to account for the high temperature magnetism of polymerized fullerenes.…”