Defective fullerenes and nanotubes as molecular magnets: An ab initio study

Using ab initio spin-density-functional calculations, we investigate the electronic and magnetic structures of a ${\mathrm{C}}_{60}$ fullerene during a structural transition to a nanotube segment by a series of Stone-Wales transformations. We find that partly opened intermediate cage structures may acquire a magnetic moment of several Bohr magnetons. Our results offer a possible explanation for the ferromagnetic behavior observed in polymerized ${\mathrm{C}}_{60}$ following exposure to high temperatures and pressures, and suggest the use of carbon nanostructures for magnetic measurements.