CAREER: Confining Magnetism to Two-Dimensions in Transition Metal Oxide Atomic Layers

非技术描述：随着现代设备中材料的尺寸接近几个原子层的厚度，原子排列的微小偏差可能会导致电子和磁性能与大块材料的性质大不相同。使用先进的合成工具，可以将不同成分的材料的原子层组合在一起，可以有效地操纵原子偏差以产生新的效果。在这个项目中，高强度x射线被用来成像薄晶体氧化膜层界面的原子尺度结构。通过对这些材料成像获得的信息有助于科学家和工程师理解为什么一些氧化物材料在厚度减少到几个原子层时失去了有用的磁性。x射线结果与高分辨率电子显微镜、磁性和输运测量以及理论计算相结合，以设计特定的氧化物材料组合，从而在单层氧化物材料中实现磁性。该项目对于设计用于信息处理、量子计算和低功耗传感器的新型材料和设备具有令人兴奋的意义。该项目提供了一个高度协作的环境，并获得了先进的技术资源，以培养本科生和研究生在下一代先进纳米材料的发展。该项目为可视化晶体学相关的抽象概念提供了低成本的工具，以促进公众对新技术相关晶体材料发展的理解。技术细节：该项目使用阿贡国家实验室和伯克利国家实验室最先进的同步加速器x射线设备，对磁性钙钛矿氧化物表面和界面的原子、电子和磁性结构进行三维非破坏性原子尺度制图。本研究提供了对发生在原子薄磁性氧化膜与其他极性和非极性钙钛矿材料之间的界面上的基本相互作用的全面理解，并建立了观察到的相互作用与这些系统的物理性质之间的联系。结合第一性原理理论，高分辨率电子显微镜和温度相关的磁性，输运和元素特异性同步加速器x射线磁二色性测量，用于设计新的氧化物异质界面，以实现在二维氧化物层中的铁磁性限制。这些材料在新型自旋电子器件中有应用。本次活动使用了广泛的尖端研究工具，用于加强本科生和研究生的教育，为他们从事科学研究和材料与器件工程的职业做好准备。该项目的一个重要组成部分是开发低成本的增强现实工具，用于将复杂的原子和电子结构可视化，用于课堂教学和K-12学校的公共宣传。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

NON-TECHNICAL DESCRIPTION: As the dimensions of materials in modern devices approach thicknesses close to a few atomic layers, small deviations in atomic arrangements can occur leading to electronic and magnetic properties which differ vastly from the properties of the bulk materials. Using advanced synthesis tools which permit the combination of atomic layers of materials with different compositions, the atomic deviations can be effectively manipulated to produce novel effects. In this project, high-intensity X-rays are used to image the atomic-scale structure of the interfaces of layers of thin crystalline oxide films. The information gained from imaging these materials is required to help scientists and engineers understand why some oxide materials lose their useful magnetic properties when their thicknesses are reduced to a few atomic layers. The X-ray results are combined with high-resolution electron microscopy, magnetic and transport measurements, and theoretical calculations to design specific combinations of oxide materials to achieve magnetism in single layers of oxide materials. This project has exciting implications for the design of novel materials and devices for information processing, quantum computing and low-powered sensors. This project provides a highly collaborative environment and access to advanced technical resources for training undergraduate and graduate students in the development of the next generation of advanced nanoscale materials. The project provides low-cost tools for visualizing abstract concepts related to crystallography to foster the public understanding of the development of new technologically-relevant crystalline materials.TECHNICAL DETAILS: This project uses state-of-the-art synchrotron X-ray facilities at the Argonne National Laboratory and the Berkeley National Laboratory to carry out three-dimensional non-destructive atomic-scale mapping of the atomic, electronic and magnetic structures of magnetic perovskite oxide surfaces and interfaces. This research provides a comprehensive understanding of the fundamental interactions which occur at the interfaces between atomically-thin magnetic oxide films and other polar and non-polar perovskite materials and establishes a link between the observed interactions and the physical properties of these systems. A combination of first principles theory, high-resolution electron microscopy and temperature-dependent magnetic, transport and element-specific synchrotron X-ray magnetic dichroism measurements is used to design novel oxide heterointerfaces for achieving the confinement of ferromagnetism in two-dimensional oxide layers. These materials have applications in novel spin-based electronic devices. The wide range of cutting-edge research tools utilized in this activity are used to enhance the education of undergraduate and graduate students to prepare them for careers in scientific research and materials and device engineering. An important component of this project is the development of low-cost augmented reality tools for visualizing complex atomic and electronic structures for classroom instruction and public outreach to K-12 schools.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.