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Theoretical study in nano-structure-physics of magnetic atom bridges and molecular bridges

磁性原子桥和分子桥纳米结构物理理论研究

基本信息

批准号：
16510075
负责人：
NAKANISHI Hiroshi
金额：
$ 1.92万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2004
资助国家：
日本
起止时间：
2004 至 2006
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-16510075/
关键词：
Atom bridge Molecular bridge nanostructure STM Magnetism First principles calculations Quantized conductance gas adsorption STM

项目摘要

We investigated the nano-physics of the magnetic atom bridges and molecular bridges with the aid of the first-principles calculations based on the density functional theory. After we researched the stability and magnetic properties of the magnetic atom bridge constructed between metal surface and STM-tip, we started researching the magnetic molecular bridges, which have their highly-reproducible structures supporting the magnetic atoms. We treated the tape-porphyrin with the transition metal atom, M, as a centre metal atom, in which M=Sc, Ti, V, Cr, Mn, Fe, Co, Ni and Cu. We found that in the case of M= Sc, Ti, V, Cr, Mn and Fe, the systems are the ferromagnetic metals. In the case of M=Co, Ni and Cu, the systems are insulators. In order to investigate the origin of the electronic property of these tapes, we also calculated the corresponding isolated unit of M porphyrin molecule, whose meso-and β-carbons are terminated by hydrogen atoms. As the results, The molecular orbital, which has the charge distribution on the meso-and β-carbons, becomes the wide energy bands when the molecules connect each other and construct the tape. So in the case where their Eigen energies lie near the Fermi energy, the corresponding tape-porphyrin is conductor.In addition, we found that the metal-insulator transition occurs when a CO molecule adsorbed on the Fe tape-porphyrin. We clarified that such a metal-insulator transition is caused by the hybridization of the dxz and dyz orbitals of Fe with the II^* g orbitals of CO molecule.

我们借助基于密度泛函理论的第一性原理计算研究了磁性原子桥和分子桥的纳米物理。在研究了金属表面和STM-tip之间构建的磁性原子桥的稳定性和磁性之后，我们开始研究磁性分子桥，其具有支撑磁性原子的高度可重复的结构。我们以过渡金属原子M为中心金属原子处理带卟啉，其中M=Sc、Ti、V、Cr、Mn、Fe、Co、Ni和Cu。我们发现，当M=Sc、Ti、V、Cr、Mn和Fe时，该体系是铁磁金属。在 M=Co、Ni 和 Cu 的情况下，系统是绝缘体。为了研究这些带的电子特性的起源，我们还计算了M卟啉分子的相应孤立单元，其内消旋碳和β-碳均以氢原子封端。结果，当分子相互连接并构建带时，介观碳和β碳上具有电荷分布的分子轨道成为宽能带。因此，当它们的本征能接近费米能时，相应的带状卟啉是导体。此外，我们发现当CO分子吸附在Fe带状卟啉上时，会发生金属-绝缘体转变。我们阐明这种金属-绝缘体转变是由 Fe 的 dxz 和 dyz 轨道与 CO 分子的 II^* g 轨道杂化引起的。