Magnetotransport, thermoelectric power, thermal conductivity and specific heat of Pr2/3Sr1/3MnO3 manganite

Abstract

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 77 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.

Electrical and thermal properties of Pr0.6Sr0.4−xAgxMnO3 (x = 0.05 and 0.1) manganite

“…However, the magnitude of j (T) lies in the range 0.4-3.4 W/mK, which is a little higher than typical amorphous material [31]. The observed value of thermal conductivity can be attributed to the presence of JT distortions [19,31]. Below 15 K, the thermal conductivity in both samples is practically equal.…”

“…In fact, thermal conductivity j is a property that reflects scattering of phonons and electrons in a material, which makes it an additional or sometimes also an alternative probe to study the complexity of the CMR phenomena. Survey through the studies on doped manganites shows two types of major behaviors [19,20]. In the paramagnetic phase, j is rather of a low value and exhibits an amorphous-like character of the temperature dependence (dj/dT [ 0).…”

Synthesis and Transport Properties of the Chromium Dioxide Films

“…В металлическом режиме температурную зависимость проводимости половинного металла можно представить в виде [12]: Наиболее важная характеристика металлического магнетикастепень спиновой поляризации носителей заряда определяется несколькими методами. Например, методом спинового клапана или изучением туннельной плотности состояний в магнетике [14,15].…”

Impact of sintering temperature on room temperature magneto-resistive and magneto-caloric properties of Pr2/3Sr1/3MnO3

“…There have been only a few reports about the Pr 2/3 Sr 1/3 MnO 3 material, having both the insulator-metal and Curie transitions close to room temperature [16,24]. Moreover, there seems to be no systematic report existing to investigate or optimize its magnetic properties with respect to the sintering temperature.…”