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

技术摘要：本项目主要研究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）自旋回波将与电输运一起用作微观探针。大部分工作将在Bechgaard盐（TMTSF）2X （X=PF6, ClO4， AsF6等）上进行。将研究具有不同钉住程度的“普通”和场致自旋密度波。从这项工作中获得的物理量包括序参量的温度依赖性、低于阈值的电场对凝析液位移的响应、高于阈值的凝析液滑动速度、高于阈值的滑动速度的时空分布、SDW记忆和重复效应，以及SDW相位波动的温度和频率依赖性。非技术摘要：该项目的目的是研究几种导电有机材料的不寻常性质。在低温下，导电电子形成半导体状态，具有称为自旋密度波（SDW）的波动磁性结构。这种SDW通常固定在潜在的材料缺陷上。然而，当超过一定阈值的小电场施加到材料上时，SDW就会滑动。在这些条件下，它成为一种新型的电流。要做的测量是电导和核磁共振自旋回波研究这些sdw的基本性质。它们包括波动磁场的大小，它的大小如何随温度变化，它的热振动，它在电场驱动下如何移动，以及当电场移除时它再次被固定的复杂方式。p: \ wickman \文摘\ clark.doc

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