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

为了实现具有各种扩展ttf配体的单组分金属分子磁体和分子超导体，本文研究了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。为了获得费米表面存在于第一中性金属络合分子[Ni(tmdt)_2] （tmdt=三亚甲基四硫丁烯二硫酸酯）中的直接证据，我们利用微悬臂进行了在高达33 T的高磁场中测量磁量子振荡即德哈斯-范阿尔芬（dHvA）振荡的实验。对[Ni(tmdt)_2]中dHvA信号的观测表明，它是一种单组分分子晶体，不仅具有低温下的金属导电性，而且具有费米表面的高质量量子振荡特性。这些结果明确地表明，在这种分子晶体中，空穴和电离子都存在三维费米面。为了制备具有高转变温度的单组分金属分子磁体，研制了与[Ni(tmdt)_2]结构相同的[Au(tmdt)_2]。与中性的双硫代镍络合物不同，中性的双硫代金络合物的总电子数为奇数。[Au(tmdt)_2]的自旋磁化率研究表明，在110K左右出现了异常的反铁磁相变，高于经典反铁磁金属Mn在100K左右的相变。最近，通过对[Au(tmdt)_2]微晶的电阻率测量，观察到其在相变温度以下的金属行为，这表明单组分金属分子磁体已经实现。由于[Ni(tmdt)_2]的费米表面与[Au(tmdt)_2]的费米表面有很大的不同，因此分子合金体系有望成为单组分分子超导体。成功制备了首个“单组分合金体系”[Ni_<1-x>Au_x(tmdt)_2]（0<x<1）。[Ni_<0.75>Au_<0.25>(tmdt)_2]单晶的电阻率在2K以下突然下降，在1.8 ~ 0.8K的温度范围内磁化率也略有下降，这可能是部分超导态出现的原因。我们认为“单组分分子超导体”可以在这样的合金体系中实现。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