Ferromagnetic amorphous oxides in the EuO-TiO sub(2) system studied by the Faraday effect in the visible region and the x-ray magnetic circular dichroism at the Eu M sub(4,5) and L sub(2,3) edges

Amorphous Eu[sub 2] TiO[sub 4] and EuTiO[sub 3] have been studied by a combination of the Faraday effect in the visible region and polarization-dependent x-ray absorption spectroscopy at the Eu M[sub 4,5] and L[sub 2,3] edges to examine the role of Eu 4f-5d exchange interactions on the ferromagnetic behavior. From the wavelength dependence of Faraday rotation angles of the amorphous EuO-TiO[sub 2] system in comparison with those of the divalent Eu chalcogenides as reported previously, it is found that the magnitude of crystal-field splitting of Eu 5d levels in the former is on the same order as that in the latter, which explains an enhanced ferromagnetic exchange interaction between Eu 4f and 5d states.