Ferromagnetic transition in europium fullerides EuxSr6−xC60

Crystal structure and magnetic properties of EuxSr6−xC60 were studied. Ferromagnetic transition was observed at 10–14 K, and magnetic moment is ascribed to Eu2+. The divalent state of Eu is also confirmed by Eu LIII-edge XANES experiments. The fact that ferromagnetic transition is observed even at a dilute case (x=1) suggests the magnetic interaction is caused through C60 molecules, that is, π-f interaction, rather than direct exchange interaction between Eu atoms.