Thermal and transport properties of manganites Nd1-xSrxMnO3 (x=0.5, 0.45)

The temperature dependencies of the specific heat, thermal diffusivity and thermal conductivity in polycrystalline Nd0.55Sr0.45MnO3 and Nd0.5Sr0.5MnO3 manganites are measured in wide temperature range of 77-300K. These characteristics reveal peculiarities at magnetic phase transition and transition into charge-ordered (CO) state. It is shown that a change of the phonon spectrum due to lattice contraction is the main reason of a sharp decrease of the thermal conductivity in Nd0.5Sr0.5MnO3 at the transition to the antiferromagnetic CO state. Using the experimental thermal diffusivity data and sound velocity data a temperature dependency of the phonon mean free path is calculated. (C) 2007 Elsevier B.V. All rights reserved.