Magnetotransport and thermal studies of Pr 2/3 Sr 1/3 MnO 3 polycrystalline sintered bulk sample are reported here. The resistivity ͑T͒ and thermoelectric power S͑T͒ data show an insulator to metal ͑I-M͒ phase transition at T P Ϸ 294 K and T S Ϸ 290 K, respectively. Magnetization measurement confirms that the sample undergoes a transition from paramagnetic to ferromagnetic phase at a defined Curie temperature T C = 280 K. A substantial increase in magnetoresistance from 2.5% at 280 K to 5% at

more »

... K has been noticed in a low magnetic field 0.15 T. Small polaron hopping model is found to be operative above the transition temperature T P , whereas electron-electron and electron-magnon scattering processes govern the low temperature metallic behavior. A detailed analysis of thermoelectric power in the ferromagnetic regime suggests that the complicated temperature dependence of S may be understood on the basis of electron-magnon scattering. A transition from decreasing high temperature thermal conductivity ͑due to local anharmonic distortions associated with small polarons͒, to an increasing thermal conductivity ͑due to decreasing of phonon-phonon scattering͒ and thereafter a peak at ϳ100 K ͑signifying a crossover from Umklapp to defect-limited scattering͒ have also been noticed. Specific heat measurements depict a pronounced anomaly near the T C , indicating the magnetic ordering and magnetic inhomogeneity in the sample.