Unusually strong orbit-lattice interactions in the RVO3 perovskites.

The thermal conductivity kappa(T) of the RVO3 crystals was measured. At T>T(infinity), RVO3 crystals conduct heat like a glass; the phonon contribution to kappa(T) is completely suppressed by spin and orbital fluctuations. In the interval T(N)<T<T(infinity), it is only partially restored by the orbital ordering due to spin fluctuations. In contrast with the amorphouslike kappa(T) at T>T(infinity), a phononlike kappa(T) was observed at T<T(N). This study shows clear-cut evidence of strong orbit-lattice coupling in RVO3 perovskites. Thermal conductivity measurement could be used as a sensitive probe to study orbital ordering.