magnetic structures of geometrically frustrated systems studied by NMR and neutron diffraction

通过核磁共振和中子衍射研究几何受挫系统的磁结构

基本信息

批准号：
12640345
负责人：
NAKAMURA Hiroyuki
金额：
$ 2.3万
依托单位：
KYOTO UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

Analyses of internal fields at she nuclear site (observed by NMR), as well as neutron diffraction results, are used to determine magnetic structures of magnetic materials. This is rather classical usage of NMR. However, analyzing procedures are not always simple but careful consideration depending on the material seems to be necessary. Conventional analyses of internal fields sometimes lead to magnetic structures much different from those deduced from neutron diffraction analyses. In particular, such discrepancy is often found in geometrically frustrated systems, where hidden parameters associated with anomalous phenomena may play crucial role. However careful examination of the origin may enable us to find new and essential concept. In this context, we performed various experiments, including NMR and neutron diffraction, for some geometrically frustrated systems and their related compounds, and tired to interpret NMR results reasonably and to understand the nature of the magnetic structure for the frustrated system.We studied (1) Laves-phase intermetallic compounds such as YMn2, (2) triangular-lattice transition-metal chalcogenides such as BaVS3, (3) tetrahedral cluster transition-metal chalcogenides such as GeV4S8, and (4) other related compounds. Although essential factors are different depending on the material, we found that both dynamic and static anisotropy of the internal field and its temperature dependence are generally remarkable in the frustrated system, indicating that it is quite important to treat these characteristics properly in NMR analyses. Further, from the investigation with use of NMR, neutron diffraction, etc. we proposed new spin and orbital structures for some frustrated systems such as YMn2 and BaVS3.

对SHE核位点内部场的分析（由NMR观察到）以及中子衍射结果，用于确定磁性材料的磁性结构。这是NMR的古典用法。但是，分析程序并不总是简单的，但是根据材料的不同，仔细考虑似乎是必要的。内部磁场的常规分析有时会导致与中子衍射分析所推论的磁性结构大不相同。特别是，这种差异通常是在几何沮丧的系统中发现的，在几何沮丧的系统中，与异常现象相关的隐藏参数可能起着至关重要的作用。但是，对起源的仔细检查可能使我们能够找到新的和基本的概念。在这种情况下，我们对某些几何沮丧的系统及其相关化合物进行了各种实验，包括NMR和中子衍射，并且疲倦以合理地解释NMR结果，并了解沮丧的系统的磁性结构的性质。）LAVES与金属间化合物，例如YMN2，（2）三角晶格过渡金属果生构，例如BAVS3，（3）四面体群集过渡金属质子质质体，例如GEV4S8和（4）其他相关化合物。尽管基本因素取决于材料的不同，但我们发现内部场的动态和静态各向异性及其温度依赖性通常在沮丧的系统中很明显，这表明在NMR分析中正确处理这些特征非常重要。此外，通过使用NMR，中子衍射等研究，我们为某些沮丧的系统（例如YMN2和BAVS3）提出了新的自旋和轨道结构。