Superparamagnetic behavior of C60Fe

Abstract A large value of the Curie constant and field dependence of magnetization of C 60 Fe sample point to the existence of superparamagnetic interaction in the compound. The observed nonequilibrium effects can be interpreted within the framework of the superparamagnetic blocking model, if one assumes that the solid consists of clusters (composed of many C 60 Fe complexes) that have large magnetic moments. A wide temperature range of irreversible magnetization of the C 60 Fe samples and a broad maximum of the susceptibility temperature dependence suggest the distribution of the cluster size. Semiempirical quantum chemical calculations show that C 60 Fe complexes might adopt high spin state.