Y替代La2/3Ca1/3MnO3体系的结构与输运行为

系统研究了(La1-xYx)2/3Ca1/3MnO3(0.0≤x≤0.3)体系的结构和输运行为.结果表明，实验样品具有很好的单相结构，随Y掺杂浓度的增加，金属—绝缘体（M—I）转变温度T-MI向低温区移动，对应的峰值电阻率ρp升高，对x=0.3样品，较未替代样品（x=0.0）增幅达8个数量级.在外加磁场下，材料表现出很强的磁电阻效应.同时，从实验结果出发，直接给出了输运特性与晶体结构之间的关联，并从双交换模型和可变程跃迁理论出发，对实验结果进行了初步讨论. 关键词： La2/3Ca1/3MnO3锰氧化物 Y替代 晶体结构 输运行为

Studies on the structure and transport properties for Y-doped La2/3Ca1/3MnO3 perovsksite manganate

The structure and transport properties of perovskite (La1-xYx)2/3Ca1/3 MnO3 (0≤x≤0.3) systems are systematically investigated. It is found that all the compounds show a single phase structure. With the increase of Y3+ doping content the metal insulator transition temperature TMI(M—I) shifts to lower temperatures. While the relevant resistance peak ρp is sharply increased, for the sample of x=0.3, it has been enhanced by eight orders of magnitude larger than the non-doped sample(x=0.0). In these materials a large magnetoresistance effect has been observed under an external magnetic field. At the same time, it is also directly shown that the correlation between the transport properties and the variation of crystal structure from the experiment result. Based on the double exchange model and the variable-range-hopping(VRH) theory, the mechanism of the influence of Y doping for La in La2/3Ca1/3MnO3 systems is also discussed.