Magnetism of C60-based molecular complexes: High-field-magnetization and magnetooptical study

Magnetization study of the C60 · TMTSF · 2CS2 molecular complex in magnetic fields up to 47 T for the temperature range 1.8–300 K and ESR spectroscopy of the molecular complex (ET)2C60 at T=1.8 K for the frequency range 60–90 GHz in magnetic fields up to 32 T provide experimental evidence that paramagnetic centers with reduced g-factor values g<1 control the magnetic properties of these solids. A model is suggested in which the renormalization of the g factor is due to the dynamic Jahn-Teller effect involving negative C60 ions that appear as defects in the crystalline structure with a weak charge transfer.