论文部分内容阅读
通过直流磁控溅射方法在ＳｒＴｉＯ３（００１）衬底上制备了一系列Ｌａ０６７Ｃａ０３３ＭｎＯ３／（Ｌａ０３５Ｎｄ０６５）２／３Ｃａ１／３ＭｎＯ３／Ｌａ０６７Ｃａ０３３ＭｎＯ３（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４２Ｋ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．这是中间层ＬＮＣＭＯ贡献的结果
A series of La067Ca033MnO3 / (La035Nd065) 2 / 3Ca1 / 3MnO3 / La067Ca033MnO3 (hereinafter abbreviated as LCMO / LNCMO) were prepared on SrTiO3 (001) substrate by DC magnetron sputtering / LCMO) epitaxial three-layer film, the middle layer of LNCMO showed semiconductor characteristics at zero field, until 4 2K did not occur paramagnetic semiconductor to ferromagnetic metal transition. Resistance measurements at zero field show that the resistance temperature characteristics of the three-layer film are significantly different from those of the single-layer LCMO or LNCMO films and are observed in the LCMO (75nm) / LNCMO (450nm) / LCMO (75nm) To two resistance peaks. Combined with the measurement of hysteresis loop, it shows that there is a certain magnetic coupling in this three-layer system, and there is also the effect of the inner molecular magnetic field. After the applied magnetic field, the resistance decreases and the peak temperature moves, resulting in the giant magnetoresistance effect. After comparison of giant magnetoresistance effect in single-layer LCMO films, it was found that in the three-layer film system, the magnetoresistance effect is enhanced to some extent, and the larger magnetoresistance effect is maintained in a wide temperature range. This is the result of the middle layer LNCMO contribution