Universal Behaviors of the Phonon Thermal Conductivity Associated with Charge/Orbital Ordering in Transition-Metal Oxides

We studied the thermal transport properties of transition-metal oxides, which have partially filled t(2g) orbitals of transition metals and exhibit intriguing phase transitions caused by orbital/charge ordering. We found that the temperature (T) dependence of the phonon thermal conductivity kappa(p) exhibits a universal behavior for all compounds; kappa(p)(T) decreases with decreasing T above the transition temperature T-c, whereas it is enhanced below T-c. This result implies that orbital/charge ordering in transition-metal oxides can be characterized by a unique T dependence of the phonon thermal conductivity.