La_(2/3)(Ca_(1-x)Mg_x)_(1/3)MnO_3(0≤x≤60%)系统中不寻常的超大磁电阻  

ANOMALOUS COLOSSAL MAGMETORESISTANCE OF La_(2/3)(Ca_(1-x)Mg_x)_(1/3)MnO_3(0≤x≤60%) SYSTEM

作　　者：牛乐园[1] 刘莉[1] 夏正才[1] 刘胜[1] 袁松柳[1] 

机构地区：[1]华中科技大学,武汉430074

出　　处：《低温物理学报》2004年第4期300-303,共4页Low Temperature Physical Letters

摘　　要：用溶胶 凝胶法并经过 14 5 0℃后处理而制备出名义组分为La2 /3(Ca1-xMg \-x) 1/3MnO3(0≤x≤ 6 0 % )多晶样品 .磁化测量表明 ,除磁转变温度因Mg掺杂而稍有降低外 ,磁性质整体上和不含Mg样品无本质上的差别 .未加磁场下阻温关系测量表明 ,即使Mg含量高达6 0 % ,实验上仍观察到绝缘体到金属的转变 .特别有意义的结果是 ,适当的Mg掺杂可明显提高转变温度附近的磁电阻效应 ,例如 ,在Mg掺杂量为 30～ 4 0 %的样品中 ,1T磁场下观察到的磁电阻甚至比不含Mg样品在La-{2/3}(Ca-{1-x}Mg-x)-{1/3}MnO-3 samples were prepared by sol-gel method and sintered at 1450℃ for 12 hours. Magnetization measurements indicate that the insulator-metal transition temperature T-p goes down gradually with the increase of Mg content, but the magnetism property has no essential difference compared with the sample without Mg. Electric transport measurements indicate that even Mg content reaches 60%, the insulator-metal transition is still observable. The most interesting result is that, the CMR around T-p can be markedly enhanced by substituting appropriate Mg ion for Ca ion. For example, the sample substituted Mg with 30 to 40 percent in 1T magnetic field has bigger CMR than the sample without Mg even in 5T magnetic field.

关 键 词：磁电阻效应 磁性质 掺杂 磁场 转变温度 多晶样品 溶胶-凝胶法 绝缘体 测量 磁化 

分 类 号：TB39[一般工业技术—材料科学与工程]