Neutron scattering studies of spin dynamics in iron-based high-temperature superconductors

非技术摘要：本研究的目的是探索和了解铁基超导体中各个相的微观起源，特别是砷化铁超导体BaFe 2-xNixAs 2，（B，K）Fe 2 A2和BaFe 2 As 2-xPx，使用中子散射作为主要工具。该研究有两个组成部分：初始材料表征和中子散射。为了进行合成，建立了一个综合材料实验室，并且可以在Rice生长所提议材料的单晶。 这些单晶的初始表征是使用Rice的设施进行的。中子散射是本研究计划的核心部分，用于研究这些材料的自旋动力学性质。特别是，单轴压力对它们的结构，磁性和自旋动力学性质的影响进行了研究。单轴压力也可以使样品去孪晶，并允许探索这些材料的无孪晶状态。技术摘要：这个NSF项目解决了引起新的集体现象，如高转变温度超导性的基本物理过程。已知表现出这些集体现象的材料是强关联电子材料。对这些现象的理解不仅增强了我们的基础科学知识，而且使我们能够设计具有新颖和可预测特性的材料。具体而言，实验研究包括中子散射实验，旨在从根本上了解铁基高转变温度超导体家族中的自旋激发。研究的目的是利用中子作为探针，探索和理解铁基超导体各相的微观起源。中子散射实验主要是在橡树岭国家实验室的高通量同位素反应堆（HFIR）和高通量中子源（SNS）上进行的。然而，该项目还利用了美国和欧洲的其他世界级设施，而HFIR和SNS没有类似的能力。这项研究的影响包括下一代中子散射的训练和阐明相关电子材料的奇异性质的性质。

Non-Technical Abstract:The objective of this research is to explore and understand the microscopic origins of various phases in iron-based superconductors, specifically the iron arsenide superconductors BaFe2-xNixAs2, (B,K)Fe2A2, and BaFe2As2-xPx, using neutron scattering as a primary tool. The research has two components: initial materials characterization and neutron scattering. For synthesis, a comprehensive materials laboratory was established and single crystals of the proposed materials can be grown at Rice. The initial characterization of these single crystals is performed using facilities at Rice. Neutron scattering, the core part of this research program, is used to study the spin dynamical properties of these materials. In particular, the effect of uniaxial pressure on their structural, magnetic, and spin dynamical properties are studied. Uniaxial pressure can also detwin the sample and allow twin-free states of these materials to be explored. Technical Abstract:This NSF project addresses the fundamental physical processes that give rise to novel collective phenomena such as high-transition temperature superconductivity. The materials known to exhibit these collective phenomena are the strongly correlated electron materials. The understanding of these phenomena not only enhances our knowledge of basic science, but also give us the ability to design materials with novel and predictable properties. Specifically, the experimental research includes neutron scattering experiments aimed at the fundamental understanding of the spin excitations in a family of iron-based high-transition-temperature superconductors. The objective of the research is to explore and understand the microscopic origins of various phases of iron-based superconductors using neutron as a probe. Neutron scattering experiments are performed mostly at the high-flux isotope reactor (HFIR) and Spallation Neutron Source (SNS) at the Oak Ridge National Laboratory. However, the project also utilizes other world-class facilities in the U.S. and Europe when similar capabilities are unavailable at HFIR and SNS. The impact of this research includes the training of the next generation of neutron scatters and elucidating the nature of the exotic properties of the correlated electron materials.