Atomic Scale Study of High-Temperature Iron-Based Superconductors

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。非技术说明：最近发现的一种新的铁基高温超导体家族在科学界引起了极大的兴趣。 这一发现为理解产生高温超导性的机制提供了新的途径。 铁基高温超导体也具有很大的应用价值。 例如，如果铁基材料可以经济高效地模制成柔性电线，承受高临界电流密度，并且在液氮温度下仍然是超导体，那么它们就有可能改变电力行业。 在该计划中，目的是提供一个框架，在该框架中，可以通过使用先进的结构和电子表征方法，结合最先进的扫描透射电子显微镜和最先进的第一原理（无参数）计算，探索铁基材料的超导性机制。该研究计划还包括在最先进的实验方法和计算建模研究材料在原子水平上的研究生的培训。对学生进行沿着实验和理论学科的培训是拟议活动的一个独特方面，预计将在当前竞争激烈的就业市场上为学生提供更广泛的就业机会。他们计划参与高中教师和学生的推广计划，以开发高中讲座和实践教学模块，特别关注直接应用于电子显微镜的物理概念。技术说明：这项研究计划的目标是获得在最近发现的铁基超导体的电子和原子结构-性质关系的基本理解，使用最先进的实验和计算建模技术的组合。他们建议通过使用原子分辨率Z衬度成像，亮场成像和电子能量损失光谱（EELS）在像差校正的扫描透射电子显微镜（STEM）中研究铁基超导体的原子和电子结构，基于密度泛函理论（DFT）的总能量第一性原理计算和动态电子散射（DES）计算来实现这一目标。他们预计，这种理论和实验并重的协同方法将产生重大而及时的影响，提供：（i）一个框架，其中可以探索铁基材料的超导机制，（ii）在原子尺度上详细了解缺陷对铁基材料宏观超导性能的影响。 该研究计划还包括在最先进的实验方法和计算建模研究材料在原子水平上的研究生的培训。对学生进行沿着实验和理论学科的培训是拟议活动的一个独特方面，预计将在当前竞争激烈的就业市场上为学生提供更广泛的就业机会。这里提出的研究项目的方法和结果也将与高中学生分享，进一步影响学生的发展和形成兴趣，并准备从事科学研究。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).NON-TECHNICAL DESCRIPTION: The recent discovery of a new iron-based family of high-temperature superconductors has generated tremendous interest in the scientific community. The discovery offers a new avenue for understanding the mechanism that gives rise to high-temperature superconductivity. The iron-based high-temperature superconductors are also of great interest for applications. For example, if the iron-based materials can be molded cost-efficiently into flexible wires, withstand high critical current densities and still be superconductors at liquid nitrogen temperatures, they offer the potential to transform the electrical power industry. In this program, the aim is to provide a framework in which mechanisms for superconductivity of the iron-based materials can be explored by using advanced methods of structural and electronic characterization combining state-of-the-art scanning transmission electron microscopes with state-of-the-art first-principles (parameter-free) calculations. The research program also includes training of a graduate student in the most advanced experimental methods and computational modeling to study materials at the atomic level. The training of students along both experimental and theoretical disciplines is a unique aspect of the proposed activity, and is expected to offer a wider range of career opportunities for the students in the current competitive job market. They plan to participate in outreach programs for high school teachers and students to develop high school lectures and hands-on teaching modules focused particularly in physics concepts that are directly applied in electron microscopy. TECHNICAL DESCRIPTION: The goal of this research program is to obtain a fundamental understanding of the electronic and atomic structure-property relationships in the recently discovered iron-based superconductors, using a combination of state-of-the-art experimental and computational modeling techniques. They propose to achieve this goal by investigating the atomic and electronic structures of the iron-based superconductors using atomic-resolution Z-contrast imaging, bright-field imaging and electron energy-loss spectroscopy (EELS) in an aberration-corrected scanning transmission electron microscope (STEM), total energy first-principles calculations based on density functional theory (DFT) and dynamical electron scattering (DES) calculations. They expect that this synergistic approach, where theory and experiment are equally emphasized, is going to have a significant and timely impact by providing, (i) a framework in which mechanisms for superconductivity of the iron-based materials can be explored, (ii) a detailed understanding at the atomic scale of the influence of defects on the macroscopic superconducting properties of the iron-based materials. The research program also includes training of a graduate student in the most advanced experimental methods and computational modeling to study materials at the atomic level. The training of students along both experimental and theoretical disciplines is a unique aspect of the proposed activity, and is expected to offer a wider range of career opportunities for the students in the current competitive job market. The methods and results of the research project proposed here will also be shared with high school students, further impacting the development and formation of students interested in and ready to pursue scientific research.