Crystal structure and magnetic properties of EuxSr6−xC60

Crystal structure and magnetic properties of EuxSr6−xC60 (x=1,3,6) were studied. They all have a bcc structure which is an isostructure to other M6C60 (M is an alkali or alkaline earth metal). The lattice constants follow the Vegard’s law, suggesting a formation of solid solution at x=1 and 3. Magnetic measurements reveals all Eu atoms are in the divalent state with a magnetic moment of 7μB (S=7/2), which is consistent with XANES experiments. Ferromagnetic correlation develops at low temperature in all three samples and seems to be caused the π-f interaction through C60 rather than the direct exchange interaction between Eu atoms.