Dynamic Correlations in Strongly Fluctuating Condensed Matter

强涨落固体之所以令人感兴趣，是因为它们的性质是反常的，潜在的有用的，并且难以预测。基于非弹性中子散射，该实验项目将提供有关此类材料中动态相关性的详细信息，从而在理解和预测其合作行为方面取得进展。要研究的材料是（i）定义明确的模型系统与凝聚态理论的最新发展。例子包括具有场诱导量子相变和扩展的高场量子临界相的自旋梯。(ii)磁性材料表现出不寻常的现象，不能令人满意地描述与现有的理论。例子包括氧化物和有机材料，其中交换相互作用不支持静态长程自旋顺序。(iii)波动影响未来技术应用可能性的材料。例子包括铁磁纳米线的组件，其中横向自旋驻波和线间相关性将被探测。科学项目将成为学生和博士后研究员教育计划的基础。他们将学习应用创新的中子散射技术在凝聚态物理学的现代问题，从而准备他们是主要的科学贡献者的空间中子源。材料的许多应用依赖于被称为波动的随机原子尺度运动或受到其严重影响。这在纳米技术中是越来越真实的，其中器件尺寸朝着原子间距减小。与波动相关的材料特性目前难以预测。因此，这里提出的实验是取得进展的关键。为了探测原子尺度上的运动，该项目将使用强大的非弹性中子散射技术。仔细分析样品的中子散射模式，可以揭示组成固体的原子之间的空间和时间相关性的详细信息。受波动强烈影响的原型磁性材料将是实验的重点。这些包括所谓的自旋梯，其中量子波动可以通过施加强磁场来调谐，由于竞争相互作用而无法有序的受抑磁系统，以及具有异常自旋波传播的铁磁纳米线。教育将是该项目的一个组成部分，学生和博士后研究员将在首席研究员的指导下使用尖端仪器和分析进行实验。目标是培养具有中子散射在材料科学中应用的专业知识的创造性实验物理学家。这是至关重要的，因为国家投资14亿美元在世界上最先进的中子散射设施在橡树岭国家实验室。

Strongly fluctuating solids are interesting because their properties are anomalous, potentially useful, and difficult to predict. Based on inelastic neutron scattering, this experimental project will providedetailed information about dynamic correlations in such materials leading to progress in understanding and predicting their cooperative behavior. The materials to be studied are (i) Well-defined model systemslinked to recent developments in condensed matter theory. Examples include spin ladders with a field induced quantum phase transition and an extended high field quantum critical phase. (ii) Magnetic materialsdisplaying unusual phenomena that cannot be described satisfactorily with existing theories. Examples include oxides and organic materials where exchange interactions do not favor static long range spin order.(iii) Materials where fluctuations affect possibilities for future technological applications. Examples include assemblies of ferro-magnetic nano-wires where transverse standing spin waves and inter-wire correlations will be probed. The scientific projects will be the basis for an educational program for students and post doctoral fellows. They will learn to apply innovative neutron scattering technique to modern problems in condensed matter physics thus preparing them to be major scientific contributors to the spallation neutronsource. Many applications of materials rely on or are severely affected by random atomic scale motion called fluctuations. This is increasingly true in nano-technology where device dimensions are reduced towards theatomic spacing. Materials properties linked to fluctuations are at present difficult to predict. Therefore experiments such as those proposed here are the key to progress. To probe motion on the atomic scale the project will use the powerful inelastic neutron scattering technique. Careful analysis of the pattern of neutron scattering from a sample reveals detailed information about spatial and temporal correlations between the atoms that make up the solid. Prototypical magnetic materials that are strongly affected by fluctuations will be the focus of the experiments. These include so-called spin-ladders where quantum fluctuations can be tuned through the application of a strong magnetic field, frustrated magnetic systems that fail to order due to competing interactions, and ferro-magnetic nano-wires with anomalous spin wave propagation. Education will be an integral part of the project where students and post doctoral fellows will carry out experiments using cutting edge instrumentation and analysis under the guidance of the principal investigator. The goal is to educate creative experimental physicists with expertise in the application of neutron scattering to materials science. This is crucial as the nation invests $1.4B in the worlds most advanced neutron scattering facility at Oak Ridge National Laboratory.