Collaborative Research: Engineering, imaging and control of three-dimensional topological magnetic materials

非技术摘要虽然世界上绝大多数数字信息都是使用纳米级设备来操纵电子电荷来处理的，但大多数信息都是使用纳米级磁域形式的电子自旋来存储的。磁性材料和纳米表征技术的最新进展揭示了由许多电子自旋形成的纳米级磁结。拓扑是描述不同类型磁结的属性，可以使新型电子设备用于传感、处理和存储信息。该合作研究项目开发了产生、操纵和表征这些打结的磁性特征的能力。该项目吸引了广泛年龄段的学生进行有意义的研究，包括培训中学生夏令营学生使用电子显微镜寻找纳米级“磁性领结”。该项目促进了各机构之间学生、教师和研究人员的积极交流，本科生和研究生研究人员都接受了广泛的材料挑战和使用新颖和先进设备的纳米级测量技术的教育。该提案的一个关键组成部分是促进国际领先科学家和工业科学家之间的合作，为研究生提供国际研究经验。这不仅将加强科学卓越性并扩大研究的影响，而且还将为研究生和本科生提供重要的教育和研究生职业机会。 技术概要纳米磁性器件的新功能需要在纳米空间尺度上控制磁序。 许多基于自旋的器件仍处于起步阶段，彻底了解基础材料和电子特性及其对器件性能的影响对于未来的应用至关重要。这项合作研究提案建立在 PI Fullerton 和 McMorran、国际和工业合作伙伴以及哈维穆德学院之间现有的强大合作基础上，以实现对纳米结构磁性材料和器件中拓扑自旋顺序的基本理解和控制能力。该研究特别感兴趣的是表现出复杂的 3D 拓扑状态和缺陷的薄膜材料的设计、操纵和成像，例如手性混合畴壁、手性螺旋、斯格明子、双斯格明子、反斯格明子和霍菲子。磁畴和缺陷的形态敏感地取决于基础材料特性以及磁场的应用、场历史和温度，其中磁畴可以以包括各种拓扑缺陷的亚稳态配置排列。该团队将开发并应用先进电子显微镜中的几种最新方法来表征这些拓扑态的结构，以及它们在超快场影响下的行为。暑期课程是为 7-12 年级和本科生开发的，旨在教育学生如何使用纳米级工具，并让他们参与有意义的监督研究。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力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 SUMMARYWhereas the vast majority of the world’s digital information is processed using nanoscale devices to manipulate the charge of electrons, most of this information is stored using the spins of electrons in the form of nanoscale magnetic domains. Recent advancements in magnetic materials and nano-characterization techniques have revealed nanoscale magnetic knots formed by the spins of many electrons. Topology is a property to describe the different types of magnetic knots, and could enable new types of electronic devices for sensing, processing, and storing information. This Collaborative Research project develops abilities to produce, manipulate, and characterize these knotted magnetic features. The project engages a wide age range of students on meaningful research, including training middle-school-aged summer camp students to use an electron microscope to search for nanoscale “magnetic bow ties”. The project promotes active exchange of students, faculty and researchers between institutions, and both undergraduate and graduate student researchers are educated in a broad range of materials challenges and nanoscale measurement techniques using novel and sophisticated equipment. A key component of the proposal is to foster collaborations between leading international and industrial scientists to provide international research experience for graduate students. This will not only strengthen the scientific excellence and broaden the impact of the research, but it will also provide important educational and post-graduate career opportunities for both graduate and undergraduate students. TECHNICAL SUMMARYNew functionality in nanomagnetic devices requires control of magnetic order at the nanometer spatial scale. Many spin-based devices are still in their infancy and a thorough understanding of the underlying materials and electronic properties and their effect on device performance will be essential for future applications. This Collaborative Research proposal builds on a strong existing collaboration between the PIs Fullerton and McMorran, international and industrial partners, and Harvey Mudd College to achieve a fundamental understanding of and ability to control the topological spin order in nano-structured magnetic materials and devices. The research is particularly interested in the design, manipulation and imaging of thin-film materials that exhibit complex 3-D topological states and defects such as chiral hybrid domain walls, chiral helixes, skyrmions, bi-skyrmions, antiskyrmions and hopfions. The morphology of the domains and defects depends sensitively on the underlying materials properties as well as on the application of magnetic fields, field history, and temperature where domains can arrange in metastable configurations including various topological defects. The team will develop and apply several recent methods in advanced electron microscopy to characterize the structure of these topological states, as well as their behavior under the influence of ultrafast fields. Summer curriculum is developed for the 7-12th grade and undergraduate levels to educate students on the use of nanoscale tools, and engage them in meaningful supervised research.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.