X-ray magnetic circular dichroism study of an orbital ordered state in the spinel-type vanadium oxide A V 2 O 4 ( A = Mn , Fe )

Spinel-type vanadium oxides ${\mathrm{FeV}}_{2}{\mathrm{O}}_{4}$ and ${\mathrm{MnV}}_{2}{\mathrm{O}}_{4}$ are considered to exhibit different types of ${\mathrm{V}}^{3+}$ orbital order from each other. In order to tackle this issue, the temperature dependence of x-ray absorption spectrum (XAS) and x-ray magnetic circular dichroism (XMCD) spectrum are investigated in both spinel compounds. The application of the sum rule to the obtained V edge XMCD spectra and the comparison with crystal-field multiplet calculations suggest a real orbital ordered state with quenched orbital angular momenta in both ${\mathrm{FeV}}_{2}{\mathrm{O}}_{4}$ and ${\mathrm{MnV}}_{2}{\mathrm{O}}_{4}$. A dissimilarity in XAS spectra between these compounds would originate from a quantitative difference of trigonal distortion.