Effect of sintering temperature on magneto-transport properties of La_(0.67)Ba_(0.33)MnO_3/Ba_(0.7)Sr_(0.3)TiO_3 composites

摘要

La_(0.67)Ba_(0.33)MnO_3-20 wt.%-Ba_(0.7)Sr_(0.3)TiO_3 composites were sintered at different temperatures in order to explore the possibility of improving the magneto-transport properties of the composites. Detail studies on the magnetic and electrical transport properties for the sintered composite samples have been performed. Results show that the sintered composites have identical ferromagnetic to paramagnetic transition temperature and filamentary feature of metallic phase. When sintering temperature higher than 1300℃, the composites show Efros-Shklovskii-like variable-range hopping in the temperature range lower than Curie temperature. For samples sintered lower than 1100℃, a dome-like resistance peak appears at a temperature well below the Curie temperature. Magnetoresistance behavior indicates the existence of spin polarized tunneling in the low temperature range. Considering the contributions from Efros-Shklovskii-like variable-range hopping and spin polarized tunneling, the resistance peak can be well fitted.