Thermal capacity, diffusion, and conductivity of Nd1−x SrxMno3 (x = 0.45 and 0.5) manganites

Abstract

Temperature dependences (77-300 K) of the thermal capacity, diffusion, and conductivity are investigated for the Nd 0.5 Sr 0.5 MnO 3 and Nd 0.55 Sr 0.45 MnO 3 polycrystalline samples. The examined characteristics show anomalous behavior in the magnetic phase transition and transition to the charge-ordered state. It is demonstrated that the main reason for a sharp decrease in the thermal conductivity during Nd 0.5 Sr 0.5 MnO 3 transition into the antiferromagnetic charge-ordered state is a change in the phonon spectrum caused by the lattice compression. A temperature dependence of the free phonon path is calculated for the examined temperature interval based on the thermal diffusion obtained and the literature data on the sound propagation velocity.