Thermal conductivity and infrared spectra study of polycrystalline La0.67Ca0.33MnO3

The thermal conductivity and infrared transmission spectra of La0.67Ca0.33MnO3 are investigated systematically. The thermal conductivity increases abruptly as the temperature is decreased through the Curie temperature. The effective charge carriers number and the frequency of transverse optic phonon corresponding to the stretching mode also increase dramatically along with decreasing temperature near Curie temperature. Combining our observation with previous reported results, we ascribe the abrupt change of thermal conductivity to the itinerating of the charge carriers due to the remarkable reduction of Jahn-Teller distortion below the Curie temperature.