Design and development of metallic crystals composed of single-component molecules

由单组分分子组成的金属晶体的设计和开发

基本信息

批准号：
14103005
负责人：
KOBAYASHI Akiko
金额：
$ 46.09万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (S)
财政年份：
2002
资助国家：
日本
起止时间：
2002 至 2005
项目状态：
已结题

项目摘要

In this work, in order to realize the single-component metallic molecular magnets and molecular superconductors with various extended-TTF ligands, the structures, physical properties and molecular functions of a series of new developed single-component complexes were investigated.To obtain direct evidence for the existence of Fermi surfaces in the first neutral metal complex molecule [Ni(tmdt)_2] (tmdt=trimethylenetetrathiafulvalenedithiolate), we have carried out experiments to measure magnetic quantum oscillations, namely de Haas-van Alphen (dHvA) oscillations, in high magnetic fields up to 33 T using a microcantilever. The observation of the dHvA signal in [Ni(tmdt)_2] demonstrates that it is a single-component molecular crystal which not only shows metallic conductivity behavior down to low temperatures, but also exhibits high-quality quantum oscillations characteristic of a Fermi surface. These results unambiguously show the existence of 3D Fermi surfaces for both holes and electr … More ons in this molecular crystal.To create the single-component metallic molecular magnets with a high transition temperature, [Au(tmdt)_2] was developed, which is isostructural to that of [Ni(tmdt)_2]. Unlike the neutral bis (dithiolato) nickel complex, the neutral bis (dithiolato) gold complex has an odd number of total electrons. The spin susceptibilities study of [Au(tmdt)_2] showed an unusual antiferromagnetic phase transition around 110K, which is higher than that of the classical antiferromagnetic metal Mn around 100K. More recently, the metallic behavior down to phase transition temperature was observed by the resistivity measurements on a microcrystal of [Au(tmdt)_2], which indicate that the single-component metallic molecular magnets have been realized.Since the Fermi surfaces of [Ni(tmdt)_2] are quite different from those of [Au(tmdt)_2], the molecular alloy system will be expected to be the single-component molecular superconductor. We have succeeded to prepare the first "single-component alloy system" [Ni_<1-x>Au_x(tmdt)_2](0<x<1). The resistivity of single crystal of [Ni_<0.75>Au_<0.25>(tmdt)_2] was abruptly deceasing below 2K, and the magnetic susceptibility was also slightly decreasing at the temperature range form 1.8 to 0.8K, which maybe stem from the partially appeared superconducting state. We think the "single-component molecular superconductor" may be realized in such an alloy system. Less

本工作为了实现具有各种延伸TTF配体的单组分金属分子磁体和分子超导体，对一系列新开发的单组分配合物的结构、物理性质和分子功能进行了研究，以获得直接证据。针对第一个中性金属配合物分子[Ni(tmdt)_2]（tmdt=三亚甲基四硫富瓦烯二硫醇）中费米面的存在，我们进行了测量磁性的实验使用微悬臂梁在高达 33 T 的高磁场中进行量子振荡，即德哈斯-范阿尔芬 (dHvA) 振荡。对 [Ni(tmdt)_2] 中 dHvA 信号的观察表明它是一种单组分分子晶体。其不仅表现出低温下的金属导电行为，而且还表现出费米表面的高质量量子振荡特性。明确地证明了该分子晶体中空穴和电子的 3D 费米面的存在。为了创建具有高转变温度的单组分金属分子磁体，开发了 [Au(tmdt)_2]，其同构结构为与中性双（二硫醇）镍络合物不同，中性双（二硫醇）金络合物的总数为奇数。 [Au(tmdt)_2] 的自旋磁化率研究表明，在 110K 左右存在不寻常的反铁磁相变，高于 100K 左右的经典反铁磁金属 Mn。最近，观察到了低至相变温度的金属行为。通过对[Au(tmdt)_2]微晶的电阻率测量，表明单组分金属分子磁体已被由于[Ni(tmdt)_2]的费米面与[Au(tmdt)_2]的费米面有很大不同，因此该分子合金体系有望成为单组分分子超导体。第一个“单组分合金系”[Ni_<1-x>Au_x(tmdt)_2](0<x<1)的单晶电阻率。 [Ni_<0.75>Au_<0.25>(tmdt)_2]在2K以下急剧下降，并且磁化率在1.8至0.8K温度范围内也略有下降，我们认为这可能源于部分出现的超导态。 “单组分分子超导体”可以在这样的合金体系中实现。