Magnetic Correlations Through Metal-Insulator Transition in Strongly Correlated Electron Materials

*非技术抽象*理解复杂行为是如何从简单和基本的定律中产生的，这是当前凝聚态物理学感兴趣的领域之一。这一个人研究项目研究了引起新现象的基本物理过程，如高转变温度超导和巨磁电阻(一种材料在磁场中表现出非常大的电阻变化)，这是由电子的集体行为引起的。过渡金属氧化物(TMO)家族中的材料展示了这些集体现象。了解这些现象不仅会增强我们的基础科学知识，还会让我们有能力设计出具有新颖和可预测性能的材料。该计划的目标是利用中子作为探测器来探索和了解TMOS中各种相的微观起源。中子散射实验将主要在橡树岭国家实验室(ORNL)升级后的高通量同位素反应堆(HFIR)和ORNL的新散裂中子源上进行。当ORNL没有类似的能力时，该项目还将利用美国和欧洲的其他世界级设施。这项研究计划的影响将包括培训下一代中子散射者，并阐明TMO奇异特性的性质。*技术摘要*这个单独的研究人员项目将建立一个将中子散射实验与基于实验室的材料工作相结合的实验计划。该项目的目的是加深我们对过渡金属氧化物(TMO)中从Mott绝缘体到金属/超导状态的相变的理解。该研究计划的目的是以中子散射为主要工具，探索和了解TMOS中各相的微观起源。该项目将专注于电子掺杂的高T_c超导体和巨磁阻(CMR)锰氧化物。该计划由两个部分组成：具有初始材料表征的先进合成和中子散射。作为这一研究计划的核心部分，中子散射将被用来研究高关联电子材料的奇异自旋和晶格动力学性质。大多数实验将在橡树岭国家实验室(ORNL)新升级的高通量同位素反应堆(HFIR)进行。然而，当HFIR没有类似的能力时，美国和欧洲的其他世界级设施将被利用。学生将接受最先进的材料合成和中子散射技术方面的培训。

***NON-TECHNICAL ABSTRACT***Understanding how complex behavior emerges from simple and basic laws is one of the areas of current interest in Condensed Matter Physics. This individual investigator project addresses the fundamental physical processes that give rise to novel phenomena, such as high-transition temperature superconductivity and colossal magnetoresistance (where a material displays a very large change in its electrical resistance when exposed to a magnetic field), resulting from the collective behavior of electrons. Materials in the family known as transition metal oxides (TMOs) exhibit these collective phenomena. Understanding these phenomena will not only enhance our knowledge of basic science, but also gives us the ability to design materials with novel and predictable properties. The objective of the program is to explore and understand the microscopic origins of various phases in the TMOs using neutrons as a probe. Neutron scattering experiments will be performed mostly at the upgraded high-flux isotope reactor (HFIR) at the Oak Ridge National Laboratory (ORNL) and on the new spallation neutron source at ORNL. The project will also utilize other world-class facilities in the U.S. and Europe when similar capabilities are unavailable at ORNL. The impact of this research program will include the training of the next generation of neutron scatters and elucidating the nature of the exotic properties of the TMOs. ***TECHNICAL ABSTRACT***This individual investigator project will establish an experimental program integrating neutron scattering experiments with lab based materials efforts. The aim of the project is to further our understanding of the phase transition from a Mott insulator to a metallic/superconducting state in transition metal oxides (TMOs). The objective of this research program is to explore and understand the microscopic origins of various phases in the TMOs using neutron scattering as a primary tool. The project will focus on electron-doped high-Tc superconductors and colossal magneto-resistance (CMR) manganese-oxides. The program has two components: advanced synthesis with initial materials characterization and neutron scattering. Neutron scattering, the core part of this research program, will be used to study the exotic spin and lattice dynamical properties of the highly correlated electron materials. Most experiments will be performed at the newly upgraded high-flux isotope reactor (HFIR) at the Oak Ridge National Laboratory (ORNL). However, other world-class facilities in the U.S. and Europe will be utilized when similar capabilities are unavailable at HFIR. Students will be trained in state-of-the art materials synthesis and neutron scattering techniques.