Experimental Studies of Organic Charge Transfer Salts

本文提出了一系列的实验来了解有机导体中物质状态的一些基本性质，并对凝聚态物理中的几个当前问题有了深入的了解。例如，贝加德盐是唯一一种表现出量子霍尔效应的材料，它是一种体三维现象。因此，它们是研究传统二维电子气相层耦合时会发生什么的独特系统。关于垂直电导率和边缘态耦合的问题是开放的和可检验的。作为超导体，这些系统至少和其他系统一样具有各向异性，并且它们的平均自由路径更长。它们是研究通量钉钉、动力学和约瑟夫森涡的极好候选者。对超导态的性质也进行了研究。在“正常”金属和场诱导自旋密度波状态下的磁场效应已经被证明是如此不寻常，以至于有大量的新现象需要解释。再加上可通约性、磁击穿、竞争序参数和挫折等问题，使得限制高场基态在理论上和实验上都是一个悬而未决的问题，这一领域有很多东西可以继续激发人们的热情。这个提议是为了继续一项主要是实验性的研究，即低维强相互作用和来自应用场的挫折如何共同作用，从而在有机导体中产生一些非常有趣的物质状态。贝加德盐是迄今为止发现的最有趣的电子材料之一。在室温下，它们是高度各向异性的金属，但在冷却时，它们经历各种转变到大量的低温状态。它们是第一批有机超导体，但这可以说是它们最不有趣的特性。根据负离子和压力的不同，基态可以从电荷或自旋密度波绝缘体转变为金属或超导体。然而，在中等磁场中发现的特性更加不寻常和引人注目。正常的金属相也非常不寻常，显示出角相关的共振和大的磁电阻，完全无法从已知的带结构中解释。

9626291 Chaikin A series of experiments are proposed to understand some of the basic properties of states of matter in organic conductors, and to gain insights into several current problems in condensed matter physics. For example, the Bechgaard salts are the only materials which exhibit the quantum Hall effect as a bulk three dimensional phenomenon. They are therefore unique systems for studying what happens when the conventional two dimensional electron gas layers are coupled. Questions as to the perpendicular conductivity and the coupling of edge states are open and testable. As superconductors these systems are at least as anisotropic as any others and they have much longer mean free paths. They are excellent candidates for investigating flux pinning, dynamics and Josephson vortices. Investigation also are proposed on the nature of the superconducting state. The magnetic field effects in both the"normal" metal and field induced spin density wave states have proven so unusual that there are a wealth of new phenomena to be explained. Coupled with the fact that questions of commensurability, magnetic breakdown, competing order parameters and frustration leave the limiting high field ground state an open question theoretically as well as experimentally, there is much to fuel continued excitement in this field. %%% This proposal is for continuation of a mostly experimental study of how low-dimensional strong interactions and frustration from applied fields act together to produce some quite interesting states of matter in organic conductors. The Bechgaard salts are among the most interesting electronic materials ever discovered. At room temperature they are highly anisotropic metals, but upon cooling they undergo a variety of transitions to a remarkable number of low temperature states. They were the first organic superconductors, but that is arguably their least interesting property. Depending on the anion and the pressure the ground states may be var ied from charge or spin density wave insulator to metal or superconductor. However, the properties discovered in moderate magnetic fields are even more unusual and striking. The normal metal phase also is extremely unusual showing angular dependent resonances and large magnetoresistances completely unexplainable from the known bandstructure.