NMR Investigations of the Static and Dynamic Properties of Spin Density Waves

自旋密度波的静态和动态特性的核磁共振研究

• 批准号: 9319304
• 负责人: W. Gilbert Clark
• 金额: $ 25.5万
• 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: 1994
• 资助国家: 美国
• 起止时间: 1994-04-01 至 1997-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9319304&HistoricalAwards=false
• 关键词: NMR; Investigations; Static; Dynamic; Properties

9319304 Clark Technical abstract: The main issues addressed by this project are the static and dynamic properties of spin density waves (SDW) in anisotropic conductors. Nuclear magnetic resonance (NMR) spin echoes will be used as a microscopic probe, in conjunction with electrical transport. Most of the work will be on the Bechgaard salts (TMTSF)2X (X=PF6, ClO4, AsF6, etc.). Both "ordinary" and field induced spin density waves with varying degrees of pinning will be investigated. The physical quantities to be obtained from this work include the temperature dependence of the order parameter, the displacement of the condensate in response to an electrical field below threshold, its sliding velocity above threshold, the spatial and temporal distribution of the sliding velocity above threshold, SDW memory and repinning effects, and the temperature and frequency dependence of SDW phason fluctuations. Non-technical abstract: The purpose of this project is to investigate an unusual property of several organic materials that conduct electricity. At low temperatures the conducting electrons form a semiconducting state with an undulating magnetic structure called a spin density wave (SDW). This SDW is usually pinned to the underlying material imperfections. When, however, a small electric field above a certain threshold is applied to the material, the SDW slides. Under these conditions, it becomes a new type of electrical current. The measurements to be made are electrical conduction and nuclear magnetic resonance spin echo studies of the basic properties of these SDWs. They include the size of the undulating magnetic field, how its size varies with temperature, its thermal vibrations, how it moves when driven by an electric field, and the complex way it becomes pinned again when the electric field is removed. p:\wickman\abstract\clark.doc

9319304克拉克技术摘要：该项目解决的主要问题是各向异性导体中自旋密度波（SDW）的静态和动态特性。核磁共振（NMR）自旋回波将与电运转运一起用作显微镜探针。大部分工作将用于Bechgaard盐（TMTSF）2x（X = PF6，Clo4，ASF6等）。将研究“普通”和场诱导的旋转密度波，并研究不同程度的固定。从这项工作中获得的物理数量包括顺序参数的温度依赖性，响应于阈值以下的电场的响应，其滑动速度高于阈值的滑动速度，滑动速度的空间和时间分布，超过阈值，SDW记忆和重新启动的SDW记忆和温度和频率依赖性sdww phason fluctucon fluctucon fluctucon fluctucon falluctection falluctect。 非技术摘要：该项目的目的是研究多种有机材料的不寻常特性。在低温下，导电电子形成一个半导体状态，其起伏的磁性结构称为自旋密度波（SDW）。该SDW通常固定在基础材料缺陷上。但是，当将一定阈值上方的小电场应用于材料上时，SDW载玻片。在这些条件下，它成为一种新型的电流。要进行的测量是对这些SDW的基本特性的电传导和核磁共振自旋回波研究。它们包括起伏的磁场的尺寸，其尺寸随温度而变化，其热振动，在通过电场驱动时如何移动以及在去除电场时再次固定的复杂方式。 P：\ Wickman \ Abstract \ Clark.doc