NMR Investigations of Spin Density Waves in Organic Metals and Vortices in Superconductors

9705369克拉克这个实验研究项目利用核磁共振技术研究了cdw和sdw一维系统中局域破缺对称基态结构的热运动和驱动运动，以及几种II型超导体中的涡旋结构的运动。研究的有机金属系统包括贝克加德盐合金系统和蓝色青铜。大多数实验将在非常宽的频率范围内使用脉冲核磁共振，最高可达高压。在超导体中，最近的核磁共振自旋回波场摇摆测量将扩展到各向异性超导体，以测量穿透深度的各向异性，并扩展到高场，以测量相干长度。计划推广核磁共振在各向异性第二类超导体中射频辅助磁通晶格退火的最新观测结果。一些非常强的磁场工作将在国家强磁场实验室进行。这种对新材料中异常基态的研究将扩展知识库，并有可能在基础固体物理学方面产生重大进展。它还将演示使用核磁共振的新方法，这些方法可能适用于其他情况。这个实验研究项目主要使用核磁共振技术来探索新型有机金属导体的基本电学性质，以及高各向异性超导体中的磁性行为。感兴趣的有机导体具有几乎一维的导电性。与传统金属不同，它们的导电性被认为是通过一种新的机制发生的，这种机制被称为“滑动电荷密度波”，它涉及到高度相关的载流子运动。这种不同寻常的效果的性质，以及可以展示它的材料，都是人们感兴趣的。这项研究的结果可能包括不同寻常的新效果或材料，可能会在技术上找到新的应用。部分工作将在国家强磁场实验室进行。这项研究项目本质上是跨学科的，涉及本科生和研究生，他们将接受良好的培训，以进入工业、政府或教育职位。***

w:\awards\awards96\num.doc 9705369 Clark This experimental research project employs techniques of nuclear magnetic resonance in study of the thermal and driven motions of the local broken symmetry ground state structures in CDW and SDW one-dimensional systems, and the motion of vortex structure in several Type-II superconductors. Organic metal systems for study include a Bechgaard salt alloy system and the blue bronze. Most of the experiments will employ pulsed NMR over a very wide range of frequencies and up to high pressures. In superconductors, recent NMR spin-echo field-rocking measurements will be extended to anisotropic superconductors to measure the anisotropy of the penetration depth; and to high field to measure the coherence length. Work is planned to extend the recent observations by NMR of rf-assisted flux-lattice annealing in anisotropic Type- II superconductors. Some very high magnetic field work will be performed at the National High Magnetic Field Laboratory. This study of unusual ground states in novel materials will extend the knowledge base and has potential to generate significant advances in basic solid state physics. It also will demonstrate new methods for using NMR which may be applicable in other circumstances. %%% This experimental research project uses primarily the technique of Nuclear Magnetic Resonance (NMR) to probe basic electrical properties of novel organic metal conductors, as well as aspects of the magnetic behavior in highly anisotropic superconductors. The organic conductors of interest exhibit nearly one-dimensional electrical conduction. Their electrical conduction is believed to occur by a novel mechanism known as a "sliding charge density wave", which involves a highly correlated motion of carriers, unlike conventional metals. The properties of this unusual effect, and materials that can exhibit it, a re of interest. Results from this research may include unusual new effects or materials which may find new application in technology. A portion of the work will be carried out at the National High Magnetic Field Laboratory. This research project is interdisciplinary in nature and involves both graduate and postgraduate students who will be excellently trained to enter positions in industry, government or education. ***