Non-collinear magnetism of Transition metal linear clusters

过渡金属线状团簇的非共线磁性

基本信息

批准号：
13640328
负责人：
FUJIMA Nobuhisa
金额：
$ 2.24万
依托单位：
Shizuoka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Transition-metal nano materials have been attracting many researchers interests because of their anomalous magnetic properties. In the present project, we have theoretically studied the atomic and magnetic structures of iron nano clusters by using the non-collinear first principles molecular dynamics, and clarified the following points.(1)Bare Fe chains : In bare Fe linear chains, magnetic alignment changes from collinear to non-collinear (and vice versa) with changing the interatomic distances. It is suggested that the change in the magnetic alignment is caused not only from the antiferromagnetic interaction between 3d electrons but also from RKKY-like interaction between 4s and 3d electrons. In the optimized interatomic distances, a dimerization occurs, especially in chains with even-number atoms, and the magnetic moments align antiparallel in unit of the dimer.(2)Fe chains in carbon nanocapsules : To stabilize the linear structures, Fe chains are encapsulated in tubal carbon nanotubes terminated by pentagonal rings. A Fe atom in the global capsule is not stable, but Fe chains are stable in tubal capsules, keeping their linear structures. Antiparallel magnetic alignments are dominant in the capsules because of the super exchange interaction between Fe and C atoms.(3)Iron oxide cluster FenOm : Parallel large magnetic moments appears for n>m, while antiparallel aliments with zero or small net magnetic moments appears for n<m. This is due to the superexchange interaction between Fe and O atoms. The atomic structures and ionization potential of iron oxide anion clusters also investigated for n=1,2 and m=1-6.

过渡金属纳米材料由于其异常磁性而吸引了许多研究人员的兴趣。在本项目中，我们从理论上研究了铁纳米簇的原子和磁性结构，使用非连续性第一原理分子动力学，并阐明了以下几点。（1）裸链链：在裸露的Fe线性链中随着变化的原子间距离，从共线变为非共线（反之亦然）。建议不仅是由3D电子之间的抗磁相互作用引起的磁比对的变化，而且还来自4s和3D电子之间的rkky样相互作用。在优化的原子间距离中，会发生二聚化，尤其是在具有均匀原子的链中，并且磁矩在二聚体单位中对齐的反平行。（2）碳纳米胶囊中的Fe链：为了稳定线性结构，Fe链被包装了在五角形环终止的输卵管纳米管中。全球胶囊中的Fe原子不稳定，但是在输管胶囊中，Fe链稳定，保持线性结构。由于Fe和C原子之间的超级交换相互作用。（3）氧化铁簇fenom：平行的大磁矩在n> m中出现，而零净磁矩零或小的净磁磁矩出现，出现了平行的大磁矩，出现了氧化铁簇fenom：平行的大磁矩，出现了平行的大磁矩，出现了抗平行的磁对齐。 n <m。这是由于Fe和O原子之间的互相互作用。氧化铁阴离子簇的原子结构和电离潜力也研究了n = 1,2和m = 1-6。