Ferromagnetism below 19 K due to unpaired spins on fullerene molecules

We report on synthesis and physical properties of a fullerene (3-aminopheny l)-1H-1,2-methano-[60]-fullerene-cobaltocene, a molecular organic ferromagn et, with a Curie temperature of 19 K. Near-infrared, mid-infrared and elect ron spin resonance spectra show that spins reside entirely on the fullerene units from which we deduce that the ferromagnetism is a consequence of the ordering of spins solely on the fullerene units. The ferromagnetic state o f the compound is characterized by a low saturation field of 40 oersted and a hysteresis of less than 1 oersted.