(1-x)La_(0.67)Ca_(0.33)MnO_3/xCuO复合体系与La_(0.67)Ca_(0.33)Mn_(1-x)Cu_xO_3电输运行为比较  

Comparative Study of Electrical Transport of(1-x)La_(0.67)Ca_(0.33)MnO_3/xCuO and La_(0.67)Ca_(0.33)Mn_(1-x)Cu_xO_3

作　　者：缪菊红[1] 袁松柳[2] 尹诗岩[2] 

机构地区：[1]南京信息工程大学数理学院,江苏南京210044 [2]华中科技大学物理学院,湖北武汉430074

出　　处：《中国稀土学报》2009年第6期786-790,共5页Journal of the Chinese Society of Rare Earths

基　　金：国家自然科学基金(10374032);江苏省高校自然科学基金;南京信息工程大学校科研基金(80116)资助

摘　　要：用不同实验方法制备了名义组分为（1-x）La0.67Ca0.33MnO3/xCuO（LCMO/CuO）和La0.67Ca0.33Mn1-xCuxO3（LCMCO）两组样品,在宽的温度范围内研究了样品的电输运行为随Cu含量x的变化关系,发现这两组样品表现出不同的行为。对于LCMCO,随x的增加,金属-绝缘体转变温度Tp迅速降低,当x=5.5%,样品表现出绝缘体导电行为;而LCMO/CuO复合样品,当x≤6%时,随x增加,Tp逐渐下降,x≥6%时,Tp不再继续降低,所有样品几乎表现出相同的电输运行为。另外,这两组样品均表现出较好的低场磁电阻效应（LFMR）,在0.3 T下样品的最大磁电阻分别达到了~76%和88%。基于样品结构以及制备过程的分析,我们认为LFMR效应的增强主要是因为颗粒边界上形成的Cu相关自旋无序层引起的。The samples with nominal composition of（1-x）La0.67Ca0.33MnO3/xCuO（LCMO/CuO）and La0.67Ca0.33Mn1-xCuxO3（LCMCO）were fabricated using different methods.The Cu content level（x） dependence on electrical transport behavior was investigated under a wide temperature range.It was found that the two series of samples had different behavior.For LCMCO,the metal-insulator transition temperature（Tp） decreased sharply with increment of x and exhibited insulator behavior when x=5.5%.While for LCMO/CuO composites,Tp shifted towards low temperature with the increase of x when x≤6%,and the samples exhibited similar electrical transport behavior when x≥6%.Furthermore,the low-field magnetoresistance（LFMR） was enhanced in both samples.The MR0 values at a magnetic field of 0.3 T for the two samples could reach ~76% and ~88%,respectively.Based on the analysis of microstructure and sample preparation process,it was discussed that the enhancement of LFMR was attributed to the formation of Cu dependent materials with local spin disorder at grain boundaries.

关 键 词：钙钛矿锰氧化物 磁电阻 自旋无序 稀土 

分 类 号：O482[理学—固体物理] TB34[理学—物理]