超巨磁电阻材料Pr_(2/3)Sr_(1/3)MnO_3薄膜输运性质的研究

Transport properties of colossal magnetoresistance of Pr_(2/3)Sr_(1/3)MnO_3 film

对 1 f噪声缺口的超巨磁电阻Pr2 3Sr1 3MnO3薄膜样品从 10K到室温的热电势值进行了测量 ,热电势为负值 ,低温下随温度线性变化 ,表现为金属扩散热电势 ,在 15 0K开始急剧减小 ,过渡到与温度T成反比的变化关系 ,与小极化子模型相符 .结合在电阻极大温度附近对电阻和 1 f噪声行为的讨论 ,对于发生在电阻极大温度附近的相变过程 。

Measurements of the thermopower were carried out, from room temperature down to 10K, on the colossal magnetoresistance (CMR) thin films of the Pr 2/3Sr 1/3MnO 3 (PSMO) sample, which showed a dramatic reduction in the 1/f noise spectrum reported previously. At low temperatures, the thermopower is negative and shows metallic diffusion behavior of linear temperature dependence. As the temperature goes up near 150K, the thermopower reduces dramatically to show the behavior of 1/T temperature dependence,which is consistent with the prediction of the small polaron model for the high temperature phase of CMR materials. Compared with the temperature dependence of the resistance and the property of the 1/f noise near the phase transition peak, the conclusion can be reached that the percolation-typed phase separation exists in the phase transition temperature region.