Separation of intrinsic and extrinsic contribution to fullerene magnetism

Magnetic and structural properties of pressure-polymerized fullerenes have been systematically studied by means of magnetometry, electron spin resonance (ESR), X-ray diffractometry and Raman spectroscopy. For several samples, the magnetization values were higher than those expected from the metallic contamination. We followed in situ the depolymerization process through the temperature dependence of the ESR signal and observed simultaneous changes in the g-factor, Raman spectra and X-ray patterns. On cooling, the magnetization values of the depolymerized samples dropped several times. Thus, the magnetic signal is directly connected with the polymerized fullerene phase and cannot be attributed to iron compounds.