LaCaMnO/LaNdCaMnO/LaCaMnO三层膜中巨磁电阻增强效应  

ENHANCED MAGNETORESISTIVE EFFECT IN TRILAYERED FILMS OF LaCaMnO/LaNdCaMnO/LaCaMnO *

作　　者：程荣胜[1,2] 李可斌[1,2] 李西军[1,2] 陈志祥[1,2] 熊曹水[1,2] 朱警生[1,2] 张裕恒 

机构地区：[1]中国科学院固体物理研究所 [2]中国科学技术大学结构分析开放研究实验室

出　　处：《物理学报》1998年第7期1193-1200,共8页Acta Physica Sinica

基　　金：国家自然科学基金;中国科学院九五重大项目基金

摘　　要：通过直流磁控溅射方法在ＳｒＴｉＯ３（００１）衬底上制备了一系列Ｌａ０６７Ｃａ０３３ＭｎＯ３／（Ｌａ０３５Ｎｄ０６５）２／３Ｃａ１／３ＭｎＯ３／Ｌａ０６７Ｃａ０３３ＭｎＯ３（以下简写为ＬＣＭＯ／ＬＮＣＭＯ／ＬＣＭＯ）外延三层膜，其中间层ＬＮＣＭＯ在零场下显示半导体特征，直到４２Ｋ都没有发生顺磁性半导体到铁磁性金属的转变．零场的电阻测量表明三层膜的电阻温度特性明显地有别于单层ＬＣＭＯ或ＬＮＣＭＯ薄膜的电阻温度特性，而且在ＬＣＭＯ（７５ｎｍ）／ＬＮＣＭＯ（４５０ｎｍ）／ＬＣＭＯ（７５ｎｍ）三层膜中观察到两个电阻峰．结合磁滞回线的测量，表明在这种三层膜系统中存在一定的磁耦合作用，而且也存在内分子磁场的作用，外加磁场后电阻下降，峰温移动，产生巨磁电阻效应，同单层ＬＣＭＯ薄膜中巨磁电阻效应比较后，发现三层膜系统中，其磁电阻效应有不同程度的增强，且在很宽的温度范围内保持较大的磁电阻效应．Abstract  A series of La 0.67 Ca 0.33 MnO 3/(La 0.35 Nd 0.65 ) 2/3 Ca 1/3 MnO 3/La 0.67 Ca 0.33 MnO 3(termed as LCMO/LNCMO/LCMO) epitaxial trilayered films, in which LNCMO under zero magnetic field exhibits semiconductor like conducting behavior down to 4.2K, have been fabricated on SrTiO 3(001) substrates by d.c. magnetron sputtering technique. The measurements of resistance show that transport properties of the trilayered films are clearly different from that of the pure LNCMO or LCMO films. In the LCMO(75nm)/LNCMO(450nm)/LCMO(75nm)film, two resistance peaks have been observed. With the measurements of magnetic hysteresis loop, it show that there may exist a magnetic exchange coupling interaction and an intra magnetic field in the trilayered film. When the external magnetic field is applied, the resistance decreases and the resistance peak shifts to higher temperature, therefore it appears colossal magnetoresistance effect. Compared with the magnetoresistance response in pure LCMO film, the enhanced magnetoresistance effect have been observed in these trilayed films, and it maintains a stronger magnetoresistance effect in a wide temperature range. We suggest it results from the middle layer LNCMO in the trilayered film.

关 键 词：LCMO LNCMO 薄膜 三层膜 巨磁电阻效应 

分 类 号：O484.43[理学—固体物理]