NMR Studies of Density Wave Phases, Superconductivity, and Polymer Electronic Conduction

密度波相、超导性和聚合物电子传导的核磁共振研究

• 批准号: 0072524
• 负责人: W. Gilbert Clark
• 金额: $ 30万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-11-01 至 2003-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0072524&HistoricalAwards=false
• 关键词: NMR; Studies; Density; Wave; Phases

This individual investigator award is to a senior faculty member for experimental investigations using NMR to measure the microscopic static and dynamic properties of the electrons that govern the key properties of superconductors, density wave materials, and conducting polymers. The project includes electrical transport and ESR measurements, often concurrently with the NMR. The measurements will be performed at extremes of temperature, pressure, and magnetic field. The studies in superconductivity include rf-induced flux lattice annealing using NMR spin echoes and measurements of apparently p-wave superconductivity in the organic conductor (TMTSF)(2)PF(6) under pressure. Experiments on density wave materials will include the study of the magnetic field-induced spin-density wave (SDW) phase of (TMTSF)(2)PF(6) under pressure, investigation of thermal SDW phasons below 4 K in (TMTSF)(2)P(1-x)As(x)F(6) to resolve the conflict in interpreting the SDW, and measurement of repinning dynamics. NMR and ESR will be used to investigate the mechanisms for electron charge propagation and the role of disorder in "metallic" and metal-insulating polypyrrole-PF(6). High frequency NMR instrumentation that benefits this research and the larger user community will be developed. This mix of instrumentation techniques and challenging research problems will provide valuable preparation of the participating students and postdocs for their future academic or industrial careers.%%%This individual investigator award is to a senior faculty member for a project that uses nuclear magnetic resonance, electron spin resonance, and electrical transport to study the properties of electrons in several materials, such as superconductors, density wave systems, and an electrically conducting polymer. Many of the measurements involve extremes of high field, high frequency, high pressure, and low temperatures, along with some development of the instrumentation to carry them out. One of the major goals of this project is to investigate the response of collective electron states, such as vortices in superconductors and pinned density waves in quasi one-dimensional materials, to an external driving force. Other goals are to explore the unusual superconducting state of an organic superconductor under pressure and to determine the microscopic mechanisms of electrical conduction in a conducting polymer. Results gained from this work should contribute to knowledge of the basic physics that forms the underpinning for using superconductivity and conducting polymers in technical applications. The advances of magnetic resonance instrumentation into extremes of parameter space will benefit other groups exploiting these methods. This mix of instrumentation techniques and challenging research problems will provide valuable preparation of the participating students and postdocs for their future academic or industrial careers.***

这个个人研究者奖是一个高级教员的实验研究使用核磁共振测量微观静态和动态特性的电子，管理超导体，密度波材料和导电聚合物的关键属性。该项目包括电传输和ESR测量，通常与NMR同时进行。 将在极端温度、压力和磁场条件下进行测量。 超导电性的研究包括使用NMR自旋回波的射频诱导磁通晶格退火和在压力下有机导体（TMTSF）（2）PF（6）中明显的p波超导电性的测量。 密度波材料的实验将包括在压力下研究（TMTSF）（2）PF（6）的磁场诱导自旋密度波（SDW）相位，研究（TMTSF）（2）P（1-x）As（x）F（6）中低于4 K的热SDW相位子以解决解释SDW的冲突，以及测量repinning动力学。 NMR和ESR将用于研究电子电荷传播的机制以及“金属”和金属绝缘聚吡咯-PF（6）中无序的作用。 将开发有利于这项研究和更大用户群体的高频NMR仪器。 这种仪器技术和具有挑战性的研究问题的组合将为参与的学生和博士后提供宝贵的准备，为他们未来的学术或工业生涯。这个个人研究者奖是一个高级教员的项目，使用核磁共振，电子自旋共振和电输运研究电子在几种材料，如超导体，密度波系统，和导电聚合物的属性。 许多测量涉及高场、高频、高压和低温的极端情况，沿着发展了一些仪器来执行这些测量。 该项目的主要目标之一是研究集体电子态对外部驱动力的响应，例如超导体中的涡旋和准一维材料中的钉扎密度波。 其他目标是探索有机超导体在压力下的不寻常的超导状态，并确定导电聚合物中导电的微观机制。 从这项工作中获得的结果应该有助于基础物理知识，形成在技术应用中使用超导性和导电聚合物的基础。 磁共振仪器在参数空间极端的进展将使利用这些方法的其他团体受益。 这种仪器技术和具有挑战性的研究问题的组合将为参与的学生和博士后提供宝贵的准备，为他们未来的学术或工业生涯。