Discovery and Control of Skyrmions in 2D van der Waals Magnets

工程磁性材料在数据存储（硬盘、唱片）、音响工程（电吉他、扬声器）、交通运输（子弹头列车、悬挂系统）和许多其他方面都有突破性的发现。这个由联邦政府资助的项目旨在将传统的磁性引入纳米尺度，以实现原子尺度的磁性模式，类似于刺猬的尖刺，称为skyrmions。Skyrmion的形成为逻辑和信息存储提供了传统磁性材料无法实现的新功能。通过这笔资金，该团队的目标是在原子级薄材料中实现skyrmions，了解它们的磁性行为，并操纵它们的属性。在此过程中，该项目旨在发现新型磁性材料和技术，以提高美国在全球范围内的军事和经济竞争力，并为实现量子存储器，逻辑和通信设备的高性能和下一代应用开辟道路。该项目的直接社会影响将通过在积极的研究环境中对高中，本科和研究生进行培训以及K-12外展工作来体现，以向学生介绍STEM领域和材料科学。技术摘要磁skyrmions是拓扑保护的纳米尺寸的自旋纹理与令人兴奋的量子特性对信息和神经启发的技术。迄今为止，实验上已知的skyrmionic平台仅限于大块晶体和金属多层膜。这个项目的最终目标是通过实验稳定二维（2D）和货车德瓦尔斯分层材料中的skyrmions，并研究因降维而产生的涌现特性。该项目将以过渡金属二卤化物单分子膜及其叠栅超晶格为平台，将联合收割机的理论和实验研究相结合，探索三种不同的skyrmion实现机制：1）铁磁单分子膜中的反转对称破缺，2）铁磁单分子膜中的可调电场，3）均质双分子膜中的双电子。该项目将利用磁光克尔，洛伦兹显微镜和金刚石-NV原子力显微镜技术来实验性地了解它们的磁性。密度泛函和蒙特-卡罗的研究将提供理论的见解，这些二维skyrmionic平台的完整理解。该项目的结果将填补该领域的一个巨大的基础知识空白，建立什么标志性特征是重要的skyrmion形成在单层和几层的限制。该项目的社会影响将通过对存储器，逻辑和通信设备的新应用，并通过尖端的K-12和一般公众推广活动来体现。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 AbstractEngineering magnetic materials has led to ground-breaking discoveries in data storage (hard-drives, records), sound engineering (electric guitars, speakers), transportation (bullet trains, suspensions), and many others. This federally funded project aims to take traditional magnetism into nanometric dimensions to realize atomic-scale magnetic patterns resembling a hedgehog’s spikes, called skyrmions. Skyrmion formation offers new functionalities in logic and information storage that are not possible in traditional magnetic materials. Through this funding, the team aims to realize skyrmions in atomically thin materials, understand their magnetic behavior, and manipulate their properties. While doing so, the project aims to discover novel classes of magnetic materials and technologies that will increase the U.S military and economic competitiveness at a global scale and open ways to realize high-performance and next-generation applications towards quantum memory, logic, and communication devices. The immediate societal impacts of the project will manifest through high-school, undergraduate and graduate student training in an active research environment as well as K-12 outreach efforts to introduce students to STEM fields and materials science. Technical AbstractMagnetic skyrmions are topologically protected nanometric size spin textures with exciting quantum properties towards information and neuro-inspired technologies. To date, the experimentally known skyrmionic platforms are restricted to bulk crystals and metallic multilayer films. The ultimate goal of this project is to experimentally stabilize skyrmions in two-dimensional (2D) and van der Waals layered materials and investigate emergent properties arising from reduced dimensions. The project will use transition metal dihalide monolayers and their moiré superlattices as a platform and it will combine theoretical and experimental studies to explore three different mechanisms for skyrmion realization: 1) inversion symmetry breaking in ferromagnetic monolayers, 2) tunable electric fields in ferromagnetic monolayers, 3) twistronics in homobilayers. The project will utilize magneto-optical Kerr, Lorentz microscopy, and diamond-NV atomic force microscope techniques to experimentally understand their magnetic properties. Density functional and Monte-Carlo studies will offer theoretical insights for complete understanding of these 2D skyrmionic platforms. The results from this project will fill a large fundamental knowledge gap in the field by establishing what hallmark characteristics are important for skyrmion formation in the monolayer and few-layer limit. Societal impacts of the project will manifest through new applications towards memory, logic, and communication devices and through cutting edge K-12 and general public outreach activities.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.