La2/3(CaXBa1-X)1/3MnO3材料的绝缘体-金属转变与晶界效应

稀土, 2003, 24(2): 45-49. doi: 10.3969/j.issn.1004-0277.2003.02.012

La2/3(CaXBa1-X)1/3MnO3材料的绝缘体-金属转变与晶界效应

赖恒 ^1, , 陈水源 ^2, , 陈志高 ^3, , 李永森 ^4, , 黄志高 ^5,

1.福建师范大学,物理系,福建,福州,350007

2.福建师范大学,物理系,福建,福州,350007

3.福建师范大学,物理系,福建,福州,350007

4.福建师范大学,物理系,福建,福州,350007

5.福建师范大学,物理系,福建,福州,350007;南京大学,物理系,江苏,南京,210093

基金项目: 教育部高校骨干教师资助计划(BD041) 福建省科技厅科研项目(2000E146) 福建省自然科学基金(E0010022)

关键词：电阻 , 掺杂I-M转变 , 晶界效应 , 非磁无序

Insulator to Metal Transitions and Grain Boundary Effect in La2/3(CaXBa1-X)1/3MnO3 Materials

用固相反应法制备了La2/3(CaxBa1-x)1/3MnO3(x=0.00,0.40,0.45,0.55,0.60,1.00)六种多晶CMR材料,并测量了在77K～350K范围内零磁场和0.4T外磁场下的电阻率.这些样品都出现了双电阻峰结构,采用Mott转变表达式ρ～exp(T0/T)1/4拟合了实验数据,结果表明高温峰的转变是绝缘体-金属(I-M)转变,而低温峰不是I-M转变峰,用自旋极化电子隧道效应和局域化模型解释了电阻和磁电阻行为.此外,在x=0.4～0.6掺杂范围内样品呈现出异常的电阻行为.

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材料期刊网

La2/3(CaXBa1-X)1/3MnO3材料的绝缘体-金属转变与晶界效应

Insulator to Metal Transitions and Grain Boundary Effect in La2/3(CaXBa1-X)1/3MnO3 Materials

参考文献