Frustrated superexchange interaction versus orbital order in a LaVO3 crystal

Measurements of magnetic, transport properties, thermal conductivity, and magnetization under pressure as well as neutron diffraction have been made on a single crystal and powder sample of LaVO(3). The Neel temperature was found to mark a transition from the phase with both frustrated superexchange interaction and spin-orbit lambda L.S coupling to the phase where the Jahn-Teller orbital-lattice coupling dominates. The dramatic reduction of absolute entropy in the paramagnetic phase is explained in terms of forming a long-range coherent state due to the interference between frustrated orbits and spins.