Magnetic Correlations and Quantum Critical Points

磁关联和量子临界点

• 批准号: 9977300
• 负责人: Meigan Aronson
• 金额: $ 34.38万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-12-15 至 2004-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9977300&HistoricalAwards=false
• 关键词: Magnetic; Correlations; Quantum; Critical; Points

9977300AronsonThis is an experimental condensed matter physics project that will investigate the novel T=0 magnetic phase transitions in several rare earth and actinide intermetallic compounds. The magnetic phase transition in these materials occurs below any experimentally accessible temperature or energy scale so the time and length scales of magnetic correlations are coupled in an unusual way. The research will investigate these correlations in an integral fashion. Their time decay will be studied using inelastic neutron scattering, AC susceptibility, and direct measurements of the time dependence of the magnetization. The objective of the measurements is to identify the region of the temperature-composition or temperature-pressure phase diagram on which magnetic correlations develop freely, and regions in which disorder or other intrinsic effects the scale for correlations. By comparing systems in which disorder is minimal or profound, and those in which the disorder involves moment dilution or disorder n the chemical environments of the magnetic moments, a microscopic criterion will be developed fot he extend of the truly critical regime of these unusual magnets. The effects of moment disorder will be studied in Ce1-xLaxRu2Si2, U1-xThxPdxAl3, while ligand disorder is varied in CeRu2(Si1-xGex)2 and Ce(Ru1-xTx)2Si2, (T=Fe or Ni).%%%This experimental condensed matter physics project investigates the unusual magnetic behavior in structurally complex rare earth and actinide intermetallic compounds. The magnets in these materials are thought to order only at absolute zero, which is not experimentally obtainable. As an alternative, information about the magnetic behavior is sought by studying the fluctuations in the magnetic properties over temperature intervals down to the lowest temperatures available. An analysis of the fluctuating magnetic behavior sheds light on the mechanisms tending to correlate the motions of the atomic moments in the compounds. The correlations also reflect the influence of defects and chemical disorder in the crystal lattices. All these effects must be sorted out to get to the fundamental magnetism in these materials. The results are of interest from both fundamental and technical viewpoints. The research provides excellent training in the state of the art experimental methods. The female professor in charge of this project is noted for her educational contributions.

9977300 Aronson这是一个实验凝聚态物理项目，将研究几种稀土和锕系金属间化合物中的T=0磁性相变。这些材料中的磁相变发生在任何实验可达到的温度或能量标度之下，因此磁相关的时间和长度标度以不寻常的方式耦合。研究将以整体的方式调查这些相关性。他们的时间衰减将研究使用非弹性中子散射，交流磁化率，并直接测量的磁化强度的时间依赖性。测量的目的是确定温度-成分或温度-压力相图中磁相关自由发展的区域，以及无序或其他内在影响相关尺度的区域。通过比较系统中的混乱是最小的或深刻的，和那些混乱涉及的磁矩稀释或混乱的化学环境中的磁矩，微观标准将开发的扩展这些不寻常的磁铁的真正的关键制度。在Ce 1-xLaxRu 2Si 2，U1-xThxPdxAl 3中研究了磁矩无序的影响，而在CeRu 2（Si 1-xGex）2和Ce（Ru 1-xTx）2Si 2（T=Fe或Ni）中配体无序是不同的。这个实验凝聚态物理项目研究结构复杂的稀土和锕系金属间化合物的异常磁性行为。这些材料中的磁体被认为仅在绝对零度下有序，这在实验上是无法获得的。作为一种替代方案，通过研究在温度间隔内的磁性波动，直到最低温度，来寻找有关磁性行为的信息。波动的磁性行为的分析揭示了倾向于关联化合物中的原子矩的运动的机制。这些关联也反映了晶格中缺陷和化学无序的影响。所有这些效应都必须得到整理，以了解这些材料的基本磁性。从基本和技术的角度来看，结果是有趣的。这项研究提供了最先进的实验方法的优秀培训。负责该项目的女教授因其教育贡献而闻名。