Y替代La_(2/3)Ca_(1/3)MnO_3体系的结构与输运行为  

Studies on the structure and transport properties for Y-doped La_(2/3)Ca_(1/3) MnO_3 perovsksite manganate*

作　　者：张玉凤[1] 张金仓[1] 王新燕[1] K.Tubata 曹桂新[1] 刘永生[1] 舒杨[1] 敬超[1] N.Nishimura K.Mori 曹世勋[1] 

机构地区：[1]上海大学物理系,上海200436 [2]Faculty of Engineering

出　　处：《物理学报》2004年第7期2299-2304,共6页Acta Physica Sinica

基　　金：国家自然科学基金 (批准号 :10 2 740 49);上海市教育委员会科技发展基金 (批准号 :0 1A16和 0 2AK42 );上海市教育委员会重点学科建设项目资助的课题~~

摘　　要：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TMI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 .The structure and transport properties of perovskite (La 1-xY x) 2/3Ca 1/3 MnO 3 (0≤x≤0.3) systems are systematically investigated. It is found that all the compounds show a single phase structure. With the increase of Y 3+ doping content the metal-insulator transition temperature T MI(M—I) shifts to lower temperatures. While the relevant resistance peak ρ p 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 La 2/3Ca 1/3MnO 3 systems is also discussed.

关 键 词：锰酸钙镧 Y替代 晶体结构 输运行为 巨磁电阻效应 磁性材料 

分 类 号：TG39[金属学及工艺—金属压力加工]