Princeton/Exxon Experimental Studies of Organic Charge Transfer Salts

在过去的几年里，与有机电荷转移盐相关的领域几乎爆发了。一种材料在- 1K的压力下是超导的，现在有几个化合物家族的Tc在环境压力下高达12K。此外，这些是漂亮的模型系统，用于研究大量新的物理现象，这些现象是由降维，相对较小的带宽和强电子-电子相互作用的组合产生的。在过去的一段时间里，他们在研究这些材料在强磁场中的显著特性方面表现得最为活跃。（TMTSF）2X化合物表现出独特的级联磁场诱导自旋密度波跃迁，涉及整数和分数量子霍尔效应、SDW波长与磁长和底层晶格的可通约性、朗道带和亚带以及新型量子振荡。尽管这一领域的理论发展很快，但最近的一些实验和新理论表明，仍有更多有趣的现象有待观察。因此，他们建议使用不同的化合物和额外的探针来进一步研究磁场效应。他们还计划对新的有机超导体进行一系列实验，以阐明超导的性质，以及相关性、维数和无序所起的作用。这项工作的一个重要部分是合成高质量的单晶。我们过去的研究都是在张立英博士的指导下在埃克森公司进行的合成研究才得以实现的。这项工作将继续进行并扩大，以开发和确定新材料的特性，并制备现有材料。

The field associated with organic charge transfer salts has virtually exploded within the past several years. From a single material which was superconducting at - 1K under pressure, there are now several families of compounds with Tc's up to 12K at ambient pressure. In addition, these are beautiful model systems for studying a wealth of new physical phenomena which result from a combination of reduced dimensionality, relatively small bandwidths and strong electron-electron interactions. They have been most active in the past grant period in the investigations of the remarkable properties of these materials in high magnetic fields. The (TMTSF)2X compounds show a unique cascade of magnetic field induced spin density wave transitions involving aspects of the integer and fractional Quantum Hall Effect, commensurability of the SDW wavelength with the magnetic length and the underlying lattice, Landau bands and subbands, and new types of quantum oscillations. Although there has been rapid theoretical development in this area, some of the more recent experiments and new theories suggest that there are still more interesting phenomena to be observed. They therefore propose a further study of the magnetic field effects using different compounds and additional probes. They also plan a series of experiments on the new organic superconductors to elucidate the nature of the superconductivity, and the roles played by correlations, dimensionality and disorder. A vital part of this work is the synthesis of high quality single crystals. Our past research was only made possible by the synthetic effort at Exxon under the direction of Dr. L.Y. Chaing. This effort will continue and be expanded to develop and characterize new materials as well as prepare established ones.