Synchrotron x-ray-diffraction experiments have been carried out in a perovskite-type vanadium oxide ${\mathrm{YVO}}_3$ to elucidate orbital ordering of the system. The change from C- to G-type orbital ordering at the lower magnetic transition temperature was strongly suggested. The long-range orbital ordering appears also in the high-temperature paramagnetic phase. Azimuthal-angle dependence of orbital superlattice reflections indicates that for both orbital-ordering phases the orbital occupation is approximately the $d_{\mathrm{xy}}^1{d}_{\mathrm{yz}}^1$ and $d_{\mathrm{xy}}^1{d}_{\mathrm{zx}}^1$ configuration in two sublattices, respectively. These results are in good agreement with a theoretical prediction.

• Received 28 April 2000

DOI:https://doi.org/10.1103/PhysRevB.62.R9271