Nanostructure and low-dimensional properties of CMR materials

CMR材料的纳米结构和低维特性

基本信息

批准号：
10650007
负责人：
MATSUI Masaaki
金额：
$ 2.24万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

The colossal magnetoresistance (CMR) ferromagnets of perovskite series LaィイD2n-nxィエD2CaィイD21+nxィエD2MnィイD2nィエD2ィイD23+1ィエD2 (n=2,3, and ∞) have been examined with respected to their electrical and magnetic properties. Results on the transport properties of epitaxial a-axis thin film samples with a fixed carrier concentration (x=0.3) have indicated that a reduction in the number of layers results in systematic changes in the various features. These include an increase in resistivity, a decrease in resistivity peak temperature TcィイD1pィエD1 corresponding to the metal-insulator transition, an enhancement of the maximum MR near TcィイD1pィエD1, and an increase in low temperature intrinsic MR. In order to explain the variation in these features with the number of MnOィイD12ィエD1 layers, it is necessary to take both c-axis transfer interaction an two dimensional spin fluctuation into account. These insights are important from the view points of basic understanding of the CMR mechanism and their practical applications.The lattice effect of LaィイD2n-nxィエD2CaィイD21+nxィエD2MnィイD2nィエD2OィイD23n+1ィエD2 have been investigated using thin films (n=2 and ∞) grown on various substrates with the lattice mismatch in the range of -4 〜1%. For the n=2 thin films, the curie temperature decreased very sharply with a decrease of the out-of plane lattice parameters, which results in the enhancement of the MR effect. These results are interpreted in terms of the strain effect induced by the lattice mismatch.The junctions are fabricated using the perovskite manganite (n=∞) and Fe (or Co). These results suggest that the spin polarization of tunneling electrons in these junctions is highly dependent on the electronic structure of the barrier/Fe (or Co) interface.

钙钛矿系列LAI D2N-NXIE D2CAI D21+NXIE D2MNXIE D2N D23+1 D2+1 D2（n = 2,3和∞）的巨大磁势（CMR）铁磁铁已受到对其电气和磁性的尊重。固定载体浓度（x = 0.3）的外延A轴薄膜样品的运输特性的结果表明，层数减少会导致各种特征的系统变化。其中包括增加电阻，电阻峰值温度TCY D1PIER D1的降低，对应于金属 - 绝缘体过渡，增强了TCY D1PIER D1附近的最大MR，以及低温内在MR的增加。为了用MNOI D12PIER D1层的数量来解释这些特征的变化，必须考虑两个C轴转移相互作用二维自旋波动。 These insights are important from the view points of basic understanding of the CMR mechanism and their practical applications.The lattice effect of Lay D2n-nxie D2Cai D21+nxie D2Mnixie D2nOi D23n+1 D2 have been investigated using thin films (n=2 and ∞) grown on various substrates with the lattice mismatch in the range of -4 ~1%.对于n = 2薄膜，随着面外晶格参数的降低，居里温度非常急剧降低，这导致MR效应的增强。这些结果是根据晶格不匹配引起的应变效应来解释的。使用钙钛矿锰矿（n =∞）和fe（或CO）制造交界处。这些结果表明，这些连接中隧道电子的自旋极化高度取决于屏障/Fe（或CO）界面的电子结构。