Transition between Orbital Orderings in ${\mathrm{YVO}}_3$

Evidence has been found for a change in the ordered occupation of the vanadium $d$ orbitals at the 77 K phase transition in ${\mathrm{YVO}}_3$, manifested by a change in the type of Jahn-Teller distortion. The orbital ordering above 77 K is not destroyed at the magnetic ordering temperature of 116 K, but is present as far as a second structural phase transition at 200 K. The transition between orbital orderings is caused by an increase in octahedral tilting with decreasing temperature.