New tools for static and dynamic imaging of antiferromagnetic textures using Bragg diffraction of coherent x rays

磁性材料被广泛应用于现代社会的各个领域，从能源生产到交通运输再到微电子器件。反铁磁体是磁性局部存在但在宏观尺度上相互抵消的磁体。最近，人们意识到反铁磁体可以作为新型电子器件的介质，具有增强的操作特性。这些材料还表现出具有基础科学兴趣的奇异量子特性。其中一些特性可能会在未来的量子信息技术中得到应用。任何磁铁的一个基本性质是形成小而均匀的空间区域，称为畴。这些域对于磁电子器件的运行，特别是对于信息存储是必不可少的。为了了解反铁磁体的量子特性，并确保基于它们的设备的正确操作，对这些域进行成像是必不可少的。时间分辨成像具有特殊的重要性。成像反铁磁畴是困难的。在这个项目中，利用同步加速器产生的x射线的一种新的成像技术来研究与量子物质研究相关的反铁磁体中的静态和动态行为，以及未来的电子应用。该技术独特地适用于许多以前无法成像的域类型，特别是时间分辨成像。其目的是了解这些材料在微观层面上的表现，以及如何控制它们。从长远来看，这样的研究有望有助于更好地理解量子物质，开发更快、更小的电子设备，甚至可能是新的量子信息技术。拟议的工作将在大型国家同步加速器研究设施中进行。现代同步加速器x射线散射技术需要年轻的专家。这些专家将在本项目下接受培训，以协助满足这一长期的国家需要。技术摘要：本项目利用一种新方法对反铁磁畴壁和AFM畴织构进行成像。该方法基于谐振磁布拉格散射条件下反射相干x射线束的干涉效应。它在一次曝光中产生真实空间图像，而不需要任何图像重建程序。其独特的功能包括AFM相位域的直接实时成像，以及毫秒到小时时间尺度上AFM畴动力学的实时空间研究。该项目旨在演示和开发这些以及新成像方法的其他几个功能。它将被应用于研究AFM域织构及其在几个高电流感兴趣的系统中的动力学。这些系统包括具有拓扑AFM畴织构（涡旋和skyrmions）的磁体，用于AFM自旋电子学的化合物，包括拓扑AFM自旋电子学和多铁性。该技术将为在应用和基础科学研究中使用的器件状结构中活性AFM介质的表征提供有价值的手段。这应该是相关的，例如，对反铁磁体中的奇异霍尔效应的研究，如在AFM异常霍尔效应，拓扑霍尔效应等。对于原子力显微镜自旋电子学器件工程来说，了解畴动力学是保证器件稳定性和高运行速度的关键。因此，将对原型AFM装置介质进行动态研究。与自旋电子学应用相关的AFM域控制方法的探索性原位研究也将进行。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 AbstractMagnetic materials are extensively utilized in modern society in a wide variety of fields, ranging from energy generation to transportation to microelectronic devices. Antiferromagnets are the magnets in which the magnetism exists locally but cancels out on a macroscopic scale. Recently, it was realized that antiferromagnets can be used as media for novel electronic devices with enhanced operational characteristics. These materials also exhibit exotic quantum properties of fundamental scientific interest. Some of these properties may find applications in future quantum information technologies. A fundamental property of any magnet is the formation of small uniform spatial regions called domains. These domains are essential for the operation of magneto-electronic devices, especially for information storage. To understand the quantum properties of antiferromagnets, and to ensure the correct operation of devices based on them, it is essential to image the domains. Time-resolved imaging is of a special importance. Imaging antiferromagnetic domains is difficult. In this project, a novel imaging technique using the x-rays produced by synchrotrons is utilized to investigate the static and dynamic behavior of the domains in antiferromagnets relevant to the studies of quantum matter, and to prospective electronics applications. The technique is uniquely suitable for many domain types previously inaccessible to imaging, especially to time-resolved imaging. The aim is to understand how these materials behave on the microscopic level, and how to control them. In the long term, such studies are expected to contribute towards the better understanding of quantum matter, to the development of faster and smaller electronic devices, and perhaps even to novel quantum information technologies. The proposed work will be carried out at large-scale National synchrotron research facilities. There is a recognized need for young specialists in modern synchrotron x-ray scattering techniques. Such specialists will be trained under this project, contributing to the fulfillment of this long-standing national need.Technical AbstractThis Project utilizes a new method of imaging antiferromagnetic (AFM) domain walls and AFM domain textures. The method is based on interference effects in the reflected coherent x-ray beam under the condition of resonant magnetic Bragg scattering. It produces real-space images in a single exposure, without any need for image reconstruction procedures. Its unique capabilities include direct real-space imaging of AFM phase domains, and real-space studies of the AFM domain dynamics on millisecond to hours timescales. The project aims at the demonstration and development of these and several other capabilities of the new imaging method. It will be applied to study AFM domain textures and their dynamics in several systems of high current interest. These systems include magnets with topological AFM domain textures (vortices and skyrmions), compounds utilized in AFM spintronics, including topological AFM spintronics, and multiferroics. This technique should provide valuable means for the characterization of active AFM media in device-like structures utilized both in applied and fundamental science studies. This should be relevant, for example, for the investigations of the exotic Hall-type effects in antiferromagnets, such as at the AFM anomalous Hall effect, the topological Hall effect, etc. For AFM spintronics device engineering, understanding the domain dynamics is key for ensuring device stability and high operation speed. Dynamic studies of the prototype AFM device media will therefore be carried out. Exploratory in-situ studies of the AFM domain control methods relevant to spintronics applications will also be performed.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.