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

有机金属中自旋密度波和超导体中涡流的核磁共振研究

• 批准号: 9705369
• 负责人: W. Gilbert Clark
• 金额: $ 24万
• 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: 1997
• 资助国家: 美国
• 起止时间: 1997-07-15 至 2001-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9705369&HistoricalAwards=false
• 关键词: NMR; Investigations; Spin; Density; Waves

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. ***

w：\awards\awards96\num.doc 9705369 Clark 本实验研究计划利用核磁共振技术，研究一维CDW和SDW系统中局部对称破缺基态结构的热运动和驱动运动，以及几种II型超导体中涡旋结构的运动。用于研究的有机金属系统包括Bechgaard盐合金系统和蓝青铜。 大多数实验将在非常宽的频率范围内使用脉冲NMR，并达到高压。 在超导体中，最近的NMR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。工作计划，以扩大最近的观察各向异性II型超导体的射频辅助磁通晶格退火的核磁共振。 一些非常高的磁场工作将在国家高磁场实验室进行。 这种对新材料中不寻常基态的研究将扩展知识基础，并有可能在基础固态物理学中产生重大进展。它还将展示新的方法 用于使用 这可能适用于其他情况。 %本实验研究项目主要利用核磁共振（NMR）技术来探测新型有机金属导体的基本电学性质，以及高度各向异性超导体的磁行为。 感兴趣的有机导体表现出几乎一维的导电性。它们的导电被认为是通过一种称为“滑动电荷密度波”的新机制发生的，与传统金属不同，这种机制涉及载流子的高度相关运动。 这种不寻常的效应的性质，以及能够表现出这种效应的材料，引起了人们的兴趣. 这项研究的结果可能包括不寻常的新效果或可能在技术中找到新应用的材料。部分工作将在国家高磁场实验室进行。这个研究项目是跨学科的性质，涉及研究生和研究生谁将得到良好的培训，进入行业，政府或教育职位。 ***