Origin of Robust Ferromagnetism in Eu0.95Fe4Sb12

We combine x-ray magnetic circular dichroism spectroscopy at Fe L{sub 2,3} edges, at Eu M{sub 4,5} edges, x-ray absorption spectroscopy (XAS) investigation of Eu valence, and local spin density calculations, to show that the filled skutterudite Eu{sub 0.95}Fe{sub 4}Sb{sub 12} is a ferrimagnet in which the Fe 3d moment and the Eu{sup 2+} 4f moment are magnetically ordered with dominant antiferromagnetic coupling. From Eu L{sub 3} edge XAS, we find that about 13% of the Eu have a formal valence of 3{sup +}. We ascribe the origin of ferrimagnetism at a relatively high transition temperature T{sub c} of 85 K in Eu{sub 0.95}Fe{sub 4}Sb{sub 12} to f-electron interaction with the nearly ferromagnetic [Fe{sub 4}Sb{sub 12}]{sup 2.2-} host lattice.