Local electronic and magnetic properties of ferro-orbital-ordered FeV2O4

Abstract

Local magnetic structures of spinel-type FeV2O4 were investigated using X-ray absorption and X-ray magnetic circular dichroism (XMCD) spectroscopies for V and Fe sites and Mössbauer spectroscopy for Fe sites. XMCD spectra reveal that the Fe2+ (d6) and V3+ (d2) states are coupled antiferromagnetically. From the analyses of XMCD spectra using magneto-optical sum rules, we deduced that small but finite orbital magnetic moments remain in the V 3d states, which accounts for the ferro-orbital ordering in the V sites of FeV2O4 with both the complex and real orbital states coexisting accompanied by the distortion of Fe sites. X-ray absorption fine structure spectra supports the deduction that the Fe2+ and V3+ states remain unchanged during the structural phase transitions. Mössbauer spectra also suggest that the Jahn–Teller distortion in Fe sites can be a driving force in ferro-orbital ordering.