High-Quality-Magnetic Materials Fabricated by Cluster-Assembling

通过团簇组装制备高质量磁性材料

基本信息

批准号：
08505004
负责人：
SUMIYAMA Kenji
金额：
$ 36.03万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1996
资助国家：
日本
起止时间：
1996 至 1998
项目状态：
已结题

项目摘要

We would like to establish the new paradigm, functional-material-fabrication from nano-scale clusters, which correspond to units of functional elements. The summaries of our resarch activities for three years are as follows.1) We designed and constructed a laser-vaparization type cluster deposition system with a time-of- flight mass spectrometer. The mass-spectrometric studies of transition metal clusters indicate that the clusters consiting of 7,13,15,19 atoms are magic numbers for Fe, Ti, Ta, Nb and Zr, while no marked magic number effect for Ni and Co.2) We analyzed the Fe-oxide cluster formation process by mass-spectrtometry. The abundnances of Fe_<13>O_8, Fe_<43>O_<20> are much stronger the others'. This feature is confirmed by the first principle molecular orbital calculations.3) Superparamagnetic to ferromagnetic transition is detected at around 9 nm for mono-dispersive Co clusters produced by plasma-gas-condensation.4) The assemblies of CoO coated Co clusters show very large tunneling type magnetoresistance. The logarithmic conductivity shows T^<-1> dependence, indicating monodispersivity in the cluster size and uniformity of the CoO layer thickness.5) XAFS, MCD and Magneto-optical Kerr spectra were observed for Co cluster assembled films. Two monolayered CoO is formed at the cluster surface. In the inner metallic Co cores , fcc is predominant for the cluster size, d= 6 nm. With increasing d from 6 to 13 nm, the volume fraction of hcp increases. The magneto-optical Kerr effect is enhanced at the low wave length region.

我们希望建立新的范式，即从纳米级簇制造功能材料，它对应于功能元素的单元。我们三年来的研究活动总结如下：1）我们设计并构建了带有飞行时间质谱仪的激光汽化型团簇沉积系统。过渡金属团簇的质谱研究表明，由7、13、15、19个原子组成的团簇对于Fe、Ti、Ta、Nb和Zr来说是幻数效应，而对于Ni和Co则没有明显的幻数效应。2)我们通过质谱分析了铁氧化物簇的形成过程。 Fe_<13>O_8、Fe_<43>O_<20>丰度明显高于其他元素。这一特征得到了第一原理分子轨道计算的证实。3) 在等离子气体凝聚产生的单色散 Co 团簇中，在 9 nm 附近检测到超顺磁性到铁磁性的转变。4) CoO 涂覆的 Co 团簇的组装体显示出非常大的尺寸。隧道型磁阻。对数电导率显示出T^ -1 依赖性，表明簇尺寸的单分散性和CoO层厚度的均匀性。5)观察了Co簇组装薄膜的XAFS、MCD和磁光克尔光谱。簇表面形成两个单层CoO。在内部金属 Co 核中，fcc 是簇尺寸的主导，d= 6 nm。随着 d 从 6 nm 增加到 13 nm，hcp 的体积分数增加。磁光克尔效应在低波长区域增强。