CAJ | 학술논문

用不同实验方法制备了名义组分为(1-x)La_(0.67)Ca_(0.33)MnO_3/xCuO(LCMO/CuO)和La_(0.67)Ca_(0.33)Mn_(1-x)Cu_xO_3(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T_p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,T_p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.
용불동실험방법제비료명의조분위(1-x)La_(0.67)Ca_(0.33)MnO_3/xCuO(LCMO/CuO)화La_(0.67)Ca_(0.33)Mn_(1-x)Cu_xO_3(LCMCO)량조양품,재관적온도범위내연구료양품적전수운행위수Cu함량x적변화관계,발현저량조양품표현출불동적행위.대우LCMCO,수x적증가,금속-절연체전변온도T_p신속강저,당x=5.5%,양품표현출절연체도전행위;이LCMO/CuO복합양품,당x≤6%시,수x증가,Tp축점하강,x≥6%시,T_p불재계속강저,소유양품궤호표현출상동적전수운행위.령외,저량조양품균표현출교호적저장자전조효응(LFMR),재0.3 T하양품적최대자전조분별체도료～76%화88%.기우양품결구이급제비과정적분석,아문인위LFMR효응적증강주요시인위과립변계상형성적Cu상관자선무서층인기적.
The samples with nominal composition of (1-x) (1-x)La_(0.67)Ca_(0.33)MnO_3/xCuO (LCMO/CuO) and La_(0.67)Ca_(0.33)Mn_(1-x)Cu_xO_3 (LCMCO) were fabricated using different methods. The Cu content level (x) de-pendence on electrical transport behavior was investi-gated under a wide temperature range. It was found that the two series of samples had different behavior. For LCMCO, the metal-insulator transition tempera-ture (T_p) 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 be-havior when x≥6%. Furthermore, the low-field mag-netoresistance (LFMR) was enhanced in both sam-pies. The MR_0 values at a magnetic field of 0.3 T for the two samples could reach ～76% and ～ 88%, re-spectively. 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.