Superparamagnetic behavior of C60Fe

A large value of the Curie constant and field dependence of magnetization o f C60Fe sample point to the existence of superparamagnetic interaction in t he 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 C60Fe complexes) that have large magnetic moments. A wide temperature range of irreversible magnetiza tion of the C60Fe samples and a broad maximum of the susceptibility tempera ture dependence suggest the distribution of the cluster size. Semiempirical quantum chemical calculations show that C60Fe complexes might adopt high s pin state. (C) 2000 Elsevier Science B.V. All rights reserved.