Experimental Studies of Organic Charge Transfer Salts

这项研究的目标是探索低维、强相互作用和来自应用领域的挫折如何共同作用，以产生有趣的物质状态。其中一种材料Bechgaard盐随着温度、压力和磁场的变化，表现出金属相、绝缘相、反铁磁相、密度波相、超导相、非欧姆相、准周期相和量子霍尔效应相。对准一维和准二维有机电荷转移盐的正常相、超导相和奇异相进行了磁、热、弹性和结构测量实验。在其他材料中没有发现的新现象也被研究。其中包括一系列磁场诱导的跃迁和新形式的量子振荡。此外，研究了高达65特斯拉的超强磁场对低维系统行为的影响。在这项工作中，研究了高各向异性有机导体的电子特性。通常情况下，晶体沿最佳导电方向的导电性要比沿最差导电方向的导电性好一百万倍。由于电子被限制沿着链移动，它们与其他电子的相互作用更强烈，从而导致许多不寻常的转变和性质。在室温下，材料是金属。当冷却到液氦的温度时，材料变得绝缘、磁性或超导。当施加磁场并将其定向到与链相关的不同方向时，可以注意到材料性质的显著变化。这些研究的目的是了解分子系统中金属与绝缘体、磁体和超导体之间的基本竞争。拟议研究的成功完成最终将导致用于制造新电子设备的新材料的发展。

The goal of this research is to explore how low dimensions, strong interactions and frustration from applied fields act together to produce interesting states of matter. One such material (Bechgaard salt) exhibits metallic, insulating, antiferromagnetic, density wave, superconducting, non-ohmic, quasi-periodic and Quantum Hall Effect phases as temperature, pressure and magnetic field are varied. Experiments involving magnetic, thermal, elastic, and structural measurements are conducted on normal, superconducting and exotic phases of the quasi-one and quasi-two dimensional organic charge transfer salts. New phenomena found in no other materials also are examined. These include a cascade of magnetic field induced transitions and new forms of quantum oscillations. In addition, the effects of extraordinary magnetic field, up to 65 Tesla, on the behavior of low-dimensional systems are investigated. %%% In this work, electronic properties of highly anisotropic organic conductors are studied. Typically, the conductivity is one million times better along the best conducting direction of the crystal than along the worst. Because the electrons are constrained to move along chains, they interact more strongly with other electrons, thus causing a number of unusual transitions and properties. At room temperature, the materials are metallic. On cooling to liquid helium temperatures, the materials become insulating, magnetic or superconducting. When magnetic fields are applied and oriented in different directions relative to the chains, striking changes in material properties are noted. The object of these studies is to understand the basic competition between metals and insulator, magnet and superconductor in a molecular system. The successful completion of the proposed studies ultimately will lead to the development of new materials for fabrication of new electronic devices.