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

为了实现单组分金属分子磁体和具有不同扩展TTf配体的分子超导体，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。为了获得第一个中性金属络合物分子[Ni(Tmdt)_2](tmdt=trimethylenetetrathiafulvalenedithiolate)，中费米面存在的直接证据，我们利用微悬臂梁测量了高达33T磁场下的磁量子振荡，即de Haas-van Alphen(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，不仅在低温下表现出金属电导行为，而且还表现出费米面的高质量量子振荡特征。这些结果明确地表明，对于空穴和电子…，都存在3D费米面为了制备具有较高转变温度的单组分金属分子磁体，合成了与[Ni(Tmdt)_2]同构的[Au(Tmdt)_2]。与中性的双(二硫代)镍络合物不同，中性的双(二硫代)金的络合物的总电子数为奇数。[Au(Tmdt)_2]的自旋极化率研究表明，在110K附近发生了反铁磁相变，而在100K附近，[Au(Tmdt)_2]的自旋极化率高于经典的反铁磁金属Mn。最近，通过对微晶[Au(Tmdt)_2]的电阻率测量，观察到了在相变温度以下的金属行为，这表明已经实现了单组分的金属分子磁体。由于[Ni(Tmdt)_2]的费米面与[Au(Tmdt)_2]的费米面有很大的不同，分子合金系统有望成为单组分的分子超导体。我们成功地制备了第一个“单组分合金系”[Ni_x；1-x&gt；Au_x(Tmdt)_2](0&lt；x&lt；1)。[Ni_&lt；0.75&gt；Au_&lt；0.25&gt；(Tmdt)_2]单晶的电阻率在2K以下急剧下降，在1.8~0.8K温度范围内磁化率也略有下降，这可能是由于部分超导态的存在。我们认为“单组分分子超导体”有可能在这样的合金体系中实现。较少

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