Thermal Conductivity of Manganite Perovskites: Colossal Magnetoresistance as a Lattice-Dynamics Transition

Abstract

We present the thermal conductivity $\left(\kappa \right)$ of several manganite perovskite compounds at temperatures 10–350 K and fields up to 6 T. In the metallic phase, $\kappa$ behaves as expected for a crystalline solid. In the high-temperature insulating phase, however, $d\kappa /dT>\mathrm{}0\mathrm{}$, the behavior of an amorphous solid. Unlike amorphous solids, $d\kappa /dT>\mathrm{}0\mathrm{}$ here is related not to quenched structural disorder but rather to unusually large dynamic lattice distortions accompanying charge transport. Thus, “colossal magnetoresistance” in the manganite perovskites is characterized as a transition between regimes of different lattice dynamics.