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The electronic structures of R 4f and Fe 3d states of RFe 2 O 4 (R = Er, Tm, Lu) have been investigated by employing soft x-ray absorption spectroscopy (XAS) and magnetic circular dichroism at the Fe 2p and R 3d absorption edges. It is found that the valence states of Fe and R ions are nearly Fe 2.5+ and R 3+ , and that the net magnetic moments of Fe 2+ and Fe 3+ ions are antiparallel to each other. Both R 3d and O 1s XAS spectra show that the localized R 4f states do not contribute to the multiferroicity of RFe 2 O 4 . On the other hand, the magnetization data for RFe 2 O 4 at low temperature (T ) reveal the cluster glass behavior for R = Tm and Lu, but not for R = Er. This work suggests that the T -dependent structural differences among RFe 2 O 4 , caused by different R ions, are closely related to the magnetoelectricity at low temperature.

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