Direct Observation of Electron Density Distribution of the Molecular Orbital Detected by Synchrotron Radiation X-Pay Diffraction

同步辐射X-Pay衍射直接观察分子轨道电子密度分布

基本信息

批准号：
18310073
负责人：
SAWA Hiroshi
金额：
$ 10.65万
依托单位：
High Energy Accelerator Research Organization
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

项目摘要

The Synchrotron Radiation (SR) X-ray is finding increasing use in the study of material science. In this project, we utilized the SR X-ray diffraction methods for the determination of the electronic state in the novel molecular crystals.Rarefied electron gas system at high temperature is homogeneous due to the large kinetic energy compared to the Coulomb repulsion among electrons. At extreme low temperatures, the system will tend to condense and make uneven lumps, as theoretically predicted in the early 1930's. Since these lumps carry a negative charge, they form a structure where they try to avoid each other in the spatial positioning. We call this phenomenon the Wigner crystallization. A molecular conductor (DI-DCNQI)_2Ag is insulating even at room temperature. Below 220 K, Hiraki and Kanoda suggested that the 4k_F Wigner crystal type of charge order (CO) on DCNQI molecules by NMR technique. This CO ground state was theoretically predicted by Seo, et. al. It is very interesting whether (or how) the electron crystal is stable in the real solid. Single crystal x-ray diffraction measurements using SR were performed at PF, KEK. According to the result of the structural analysis, two-fold structure in ground state consists of not only charge ordering columns but also monotonic charge dimerized columns caused by geometrical frustration among DCNQI columns. In spite of these complicated order parameters, this charge ordered structure is regarded as a Wigner crystal caused by inter-column Coulomb repulsion. This is a first direct observation of the 3D electron crystal. Furthermore, we investigated the electronic state in several molecular materials during the term of project.

同步辐射 (SR) X 射线在材料科学研究中的应用越来越广泛。在这个项目中，我们利用SR X射线衍射方法来测定新型分子晶体中的电子态。高温下的稀薄电子气系统是均匀的，因为与电子之间的库仑斥力相比动能较大。正如 20 世纪 30 年代初期的理论预测，在极低的温度下，该系统会倾向于凝结并形成不均匀的块状物。由于这些块体带有负电荷，因此它们形成了一种在空间定位中试图相互避开的结构。我们将这种现象称为维格纳结晶。分子导体 (DI-DCNQI)_2Ag 即使在室温下也是绝缘的。在 220 K 以下，Hiraki 和 Kanoda 通过 NMR 技术提出 DCNQI 分子上的电荷级 (CO) 为 4k_F Wigner 晶体类型。 Seo 等人从理论上预测了这种 CO 基态。等人。电子晶体在真实固体中是否（或如何）稳定是非常有趣的。使用 SR 的单晶 X 射线衍射测量在 PF、KEK 进行。根据结构分析结果，基态二重结构不仅由电荷有序柱组成，还由DCNQI柱之间的几何挫败引起的单调电荷二聚柱组成。尽管有这些复杂的有序参数，这种电荷有序结构被认为是由柱间库仑斥力引起的维格纳晶体。这是对 3D 电子晶体的首次直接观察。此外，我们在项目期间研究了几种分子材料的电子态。

项目成果

期刊论文数量（0）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Correlation between crystal structures of CaAlSi with and without superlattice and superconduction properties

有超晶格和无超晶格的CaAlSi晶体结构与超导性能的相关性

DOI：
发表时间：
2006
期刊：
Phys. Rev. B 74
影响因子：
0
作者：
S.Kuroiwa;H.Sagayama;T.Kakiuchi;H.Sawa;et al.
通讯作者：
et al.

Two Types of Multistack Structures in MgB2-Type Superconductor CaAlSi

DOI：
10.1143/jpsj.75.043713
发表时间：
2006-04
期刊：
Journal of the Physical Society of Japan
影响因子：
1.7
作者：
H. Sagayama;Y. Wakabayashi;H. Sawa;T. Kamiyama;A. Hoshikawa;S. Harjo;K. Uozato;A. Ghosh;M. Tokunaga;T. Tamegai
通讯作者：
H. Sagayama;Y. Wakabayashi;H. Sawa;T. Kamiyama;A. Hoshikawa;S. Harjo;K. Uozato;A. Ghosh;M. Tokunaga;T. Tamegai

Iron Vacancy Ordered Y_Fe2O3(001) Epitaxial Fims : The Crystal Structure and Electrical Resistivity

铁空位有序Y_Fe2O3(001)外延膜:晶体结构和电阻率