Design of Novel Superconductors and Magnetic Conductors Based on Stepwise π-Stacking Structures

基于阶梯式π堆叠结构的新型超导体和磁导体设计

基本信息

批准号：
11304048
负责人：
INABE Tamotsu
金额：
$ 25.45万
依托单位：
Hokkaido University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2002
项目状态：
已结题

项目摘要

Phthalocyanine (Pc) complexes with axial CN ligands were utilized for development of novel conductors based on the originally devised stepwise stacking. When the central metal ion is nonmagnetic Co^<III> normal conductors can be obtained, while when it is magnetic Fe^<III> magnetic conductors can be obtained.Electrochemical oxidation of [Co^<III>(Pc)(CN)_2]^- yields the neutral radical species in which the Pc ligand becomes open-shell structure. The crystal constructed solely with this species was not highly conducting while co-crystallization with solvent molecules improved the conductivity due to the efficient π-π stacking. Various stacking structures depending on the solvent species have been obtained. The neutral radical crystals are semiconductors due to the electron correlation effect, while crystallization with the anion (partially oxidized salt) gage metallic conductors. Their formation depends on the cationic species, and six partially oxidized salts with various π-π stacking … More structures have been obtained. Among them the crystal with double two-dimensional sheeto structure has been found to maintain metallic character at low temperatures under high pressure.Electrochemical oxidation of [Co^<III>(Pc)(CN)_2]^- gave isomorphous crystals with the Co salts. For the one-dimensional system, the physical properties of the Co and Fe salts were investigated in detail. Electronic structure was found to be identical based on the thermoelectric power and optical reflectance measurements. On the other hand, the electrical conductivity was found to be dramatically different from each other , the resistivity is almost constant for the Co salt, while it shows insulating behavior at low temperature for the Fe salt. This is due to the existence of periodically arranged magnetic moments at the center of the Pc rings. As an important consequence, we have found that the resistivity decreases by applying external magnetic field. It is unusual that such a one-dimensional system shows "giant negative magnetoresistance". Less

基于最初设计的逐步堆叠，利用具有轴向CN配体的酞菁（Pc）络合物来开发新型导体，当中心金属离子是非磁性Co^<III>时，可以获得正常导体，而当中心金属离子是磁性Fe^<时，可以获得正常导体。可以获得III>磁导体。[Co^<III>(Pc)(CN)_2]^-的电化学氧化产生中性自由基物质，其中Pc配体变成单独用该物质构建的晶体的导电性不高，而与溶剂分子共结晶由于有效的 π-π 堆叠而获得了中性自由基的电导率。由于电子关联效应，晶体是半导体，而阴离子（部分氧化盐）结晶则成为金属导体，其形成取决于阳离子种类，以及具有各种不同的六种部分氧化盐。获得了π-π堆积结构，其中双二维片状结构的晶体在低温高压下仍能保持金属特性。[Co^<III>(Pc)(CN)的电化学氧化。 )_2]^- 与 Co 盐形成同质晶体。对于一维系统，根据热电势和光学反射率，详细研究了 Co 和 Fe 盐的物理性质。另一方面，发现Co盐的电导率彼此显着不同，电阻率几乎恒定，而Fe盐在低温下表现出绝缘行为，这是由于存在。作为一个重要的结果，我们发现通过施加外部磁场，这种一维系统表现出“巨大的负磁阻”，这是不寻常的。