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

为了实现含多种扩展TTF配体的单组分金属分子磁体和分子超导体，本工作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，为第一个中性金属配合物分子[Ni（tmdt）_2]中费米面的存在提供了直接证据。（tmdt=trimethylenetetrathiafulvalenedithiolate），我们已经进行了实验来测量磁量子振荡，即de Haas-van Alphen（dHvA）振荡，在高达33 T的高磁场中使用微悬臂梁。对[Ni（tmdt）_2]中dHvA信号的观测表明，它是一种单组分分子晶体，不仅在低温下表现出金属导电行为，而且表现出费米面的高质量量子振荡特性。这些结果清楚地表明了空穴和电子的三维费米面的存在。 关于我们 为了制备具有高转变温度的单组份金属分子磁体，研制了与[Ni（tmdt）_2]同构的[Au（tmdt）_2]。与中性双（二硫羟合）镍配合物不同，中性双（二硫羟合）金配合物具有奇数个总电子。[Au（tmdt）_2]的自旋极化率研究表明，在110 K附近出现了一个反常的反铁磁相变，比经典的反铁磁金属Mn在100 K附近的自旋极化率要高。最近，通过对[Au（tmdt）_2]微晶的电阻率测量，观察到了低至相变温度的金属行为，这表明单组分金属分子磁体已经实现，由于[Ni（tmdt）_2]的费米面与[Au（tmdt）_2]的费米面有很大的不同，该分子合金体系有望成为单组分分子超导体。我们成功地制备了第一个“单组元合金系”[Ni_<1-x>Au_x（tmdt）_2]（0&lt;x&lt;1）。[Ni_<0.75>Au_<0.25>（tmdt）_2]单晶的电阻率在2K以下急剧下降，磁化率在1.8 ~ 0.8K范围内也略有下降，这可能是由于部分超导态的出现。我们认为在这样的合金体系中可能实现“单组分分子超导体”。少

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