Interplay between orbital ordering and lattice distortions in LaMnO3, YVO3, and YTiO3

We have studied the interplay between orbital ordering, Jahn-Teller and ${\mathrm{GdFeO}}_{3}$-type lattice distortions in perovskite-type transition-metal oxides using model Hartree-Fock calculations. It has been found that the covalency between A-site cations and oxygens causes interaction between the Jahn-Teller and ${\mathrm{GdFeO}}_{3}$-type distortions. The present calculations explain why the d-type Jahn-Teller distortion and orbital ordering compatible with it are realized in ${\mathrm{LaMnO}}_{3},$ ${\mathrm{YVO}}_{3},$ and ${\mathrm{YTiO}}_{3}.$