Effects of rare-earth size on the electronic structure of La_1-xLu_xVO₃

The electronic structure of La_1-xLu_xVO₃(x=0, 0.2, 0.6 and 1) single crystals has been investigated using soft x-ray absorption spectroscopy, soft x-ray emission spectroscopy, and resonant soft x-ray inelastic scattering to study the effects of rare-earth size. The x-ray absorption and emission spectra at the O K-edge present a progressive evolution with R-site cation, in agreement with local spin density approximation calculations. This evolution with R, together with the temperature dependence of the O K-edge spectra, is attributed to changes in the crystal structure of La_1-xLu_xVO₃. The crystal-field dd^∗ excitations probed by resonant inelastic x-ray scattering at the V L₃-edge exhibit an increase in energy and enhanced intensity with the decrease of R-site ionic radius, which is mainly attributed to the increased tilting magnitude of the VO₆ octahedra. Upon cooling to ∼95K, the dd^∗ excitations are prominently enhanced in relative intensity, in agreement with the formation of the Jahn-Teller distortion in the orbital ordering phase. Additionally, the dd^∗ transitions of the mixed compounds are noticeably suppressed with respect to those of the pure compounds, possibly owing to the formation of C-type orbital ordering induced by large R-site size variances.