Collaborative Research: Spin Transport in Nonrelatisvistically Spin-split Antiferromagnets

在1970年诺贝尔奖演讲中，路易斯·纳姆萨伊尔对反铁磁体（原子附近磁矩方向相反的材料）的著名描述很有趣，但毫无用处。这是由于它们的净磁矩消失，这使得难以通过外加磁场控制反铁磁体的性质。50年后，反铁磁体作为铁磁体的潜在替代品出现了——在商业存储应用中，原子磁矩取向相同的材料。与铁磁体不同，反铁磁体可以在数量级上提高速度和存储密度。然而，利用这一潜力需要为反铁磁体开发有效的信息写入和读出协议，这比用于铁磁体的协议更具挑战性。该项目通过利用新发现的一类反铁磁体的独特性质来解决这一挑战，该反铁磁体在某些晶体方向上表现出无补偿磁矩。虽然这些反铁磁体的净磁矩仍然消失，但只要这些反铁磁体的单晶膜生长方法已经成功开发，这种特性允许与铁磁体相似的信息写入和读出协议。这个合作项目汇集了特拉华大学和内布拉斯加州大学林肯分校的实验和理论专业知识，最终目标是开发基于这种新型反铁磁体的记忆细胞。这项合作研究将阐明这种新型反铁磁体的独特性质，并具有彻底改变信息处理和存储的潜力。该项目将为早期职业团队成员提供现代实验和理论方法的宝贵培训，为他们在材料科学领域的前沿研究做好准备。该项目强调纳入来自代表性不足的少数群体的学生，为他们提供接触高级跨学科研究的机会，丰富他们的专业准备。研究小组将与工业研究人员合作，提供智力刺激和重要的教育组成部分，以提供工业就业机会。利用特拉华大学现有的项目，该团队将扩展到高中，吸引少数民族高中生，激发他们对科学和工程的兴趣。此外，团队成员将积极参与美国国家科学基金会资助的内布拉斯加大学林肯分校和塔斯基吉大学之间的材料研究和教育合作伙伴关系（PREM）计划。拟议的研究结果将通过现代多媒体渠道传播给更广泛的受众，包括nsf支持的在线资源Funsize Physics。由于反铁磁体的开关速度和存储密度提高了几个数量级，因此在自旋电子器件应用中取代铁磁体具有很大的潜力。实现这一潜力需要开发有效的反铁磁体序参量的电气控制和检测，即nsamel矢量，这比控制和检测铁磁体的磁化强度更具挑战性。该提案通过利用属于支持动量依赖自旋分裂的空间群的反铁磁材料的独特性质来解决这一挑战。其中有室温反铁磁性金属RuO2，其电子带沿某些晶体学方向发生自旋分裂。这项提议需要实验和理论研究的合作，目标是利用这些非相对论性自旋分裂反铁磁体提供的优势。最终目标是演示nsamel矢量的电气控制和检测，最终实现在室温下具有大隧道磁电阻的全功能反铁磁隧道结。通过从根本上推进我们对这些现象背后的物理和材料科学的理解，所提出的研究将有助于具有卓越性能的自旋电子器件的技术发展。研究团队将与工业研究人员合作，为潜在的工业就业机会提供智力刺激和有价值的见解。此外，该项目将为早期职业团队成员提供现代实验和理论方法的必要技能，这对于在材料科学前沿进行研究至关重要。该项目强调纳入来自代表性不足的少数群体的学生，为他们提供接触高级跨学科研究的机会，丰富他们的专业准备。利用特拉华大学现有的项目，该团队将接触到高中，吸引少数民族高中生，激发他们对科学和工程的兴趣。此外，团队成员将积极参与美国国家科学基金会资助的内布拉斯加大学林肯分校和塔斯基吉大学之间的材料研究和教育合作伙伴关系（PREM）计划。拟议的研究结果将通过现代多媒体渠道传播给更广泛的受众，包括nsf支持的在线资源Funsize Physics。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 SUMMARYIn his 1970 Nobel Prize Lecture, Louis Néel famously described antiferromagnets – materials with nearby magnetic moments of atoms being oriented in opposite directions, as interesting but useless. This is due to their vanishing net magnetic moment which makes difficult to control properties of antiferromagnets by an applied magnetic field. Jump forward 50 years, antiferromagnets have emerged as potential replacements for ferromagnets – materials with magnetic moments of atoms being oriented in the same direction, in commercial memory applications. Unlike ferromagnets, antiferromagnets can improve speed and storage density by orders of magnitude. However, harnessing this potential requires the development of efficient information write and read-out protocols for antiferromagnets, which is much more challenging than those used for ferromagnets. This project addresses this challenge by exploiting unique properties of a newly discovered class of antiferromagnets that exhibit an uncompensated magnetic moment along certain crystal directions. While the net magnetic moment of these antiferromagnets remains vanishing, this property allows similar information write and read-out protocols as those used for ferromagnets, provided that the methods to grow single-crystal films of these antiferromagnets have been successfully developed. This collaborative project brings together the experimental and theoretical expertise of the University of Delaware and University of Nebraska-Lincoln with the ultimate goal of developing a memory cell based on this new class of antiferromagnets. The collaborative research will elucidate the unique properties of this new class of antiferromagnets and holds potential to revolutionize information processing and storage. The project will provide valuable training in modern experimental and theoretical methods for early career team members, preparing them for cutting-edge research in materials science. The project emphasizes the inclusion of students from underrepresented minority groups, providing them with exposure to advanced interdisciplinary studies and enriching their professional preparation. The research team will collaborate with industrial researchers offering intellectual stimulus and an important educational component regarding career opportunities in industry. Leveraging the existing program at University of Delaware, the team will outreach to high schools, engaging minority high-school students and inspiring their interest in science and engineering. Additionally, team members will actively participate in the NSF-funded Partnerships for Research and Education in Materials (PREM) program between the University of Nebraska-Lincoln and Tuskegee University. Results of the proposed research will be disseminated to a broader audience via modern multimedia channels including an NSF-supported online resource Funsize Physics.TECHNICAL SUMMARYAntiferromagnets hold great potential for replacing ferromagnets in spintronic device applications due to their orders of magnitude enhanced switching speed and storage density. Realizing this potential requires the development of efficient electric control and detection of the antiferromagnets order parameter, known as the Néel vector, which is much more challenging than the control and detection of the magnetization in ferromagnets. This proposal addresses this challenge by exploiting unique properties of the antiferromagnetic materials that belong to a space group supporting momentum-dependent spin splitting. Among them is RuO2 – the roomtemperature antiferromagnetic metal, exhibiting spin splitting of its electronic bands along certain crystallographic directions. The proposal entails a collaborative effort involving experimental and theoretical research, with the goal of harnessing the advantages offered by these nonrelativistically spin-split antiferromagnets. The ultimate goal is to demonstrate the electrical control and detection of the Néel vector, culminating in the realization of a fully functional antiferromagnetic tunnel junction with a large tunneling magnetoresistance at room temperature. By fundamentally advancing our understanding of the physics and materials science underlying these phenomena, the proposed research will contribute to the technological development of spintronic devices with superior performance. The research team will collaborate with industrial researchers providing intellectual stimulus and valuable insights into potential career opportunities in industry. Additionally, the project will equip early career team members with necessary skills in modern experimental and theoretical methods, essential for conducting research at the frontiers of materials science. The project emphasizes the inclusion of students from underrepresented minority groups, providing them with exposure to advanced interdisciplinary studies and enriching their professional preparation. Leveraging the existing program at University of Delaware, the team will reach out to high schools, engaging minority high-school students and inspiring their interest in science and engineering. Furthermore, team members will actively participate in the NSF-funded Partnerships for Research and Education in Materials (PREM) program between University of Nebraska-Lincoln and Tuskegee University. Results of the proposed research will be disseminated to a broader audience via modern multimedia channels including an NSF-supported online resource Funsize Physics.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.