RII Track-4: Exploring Ferromagnetism in Two-Dimensional Van Der Waals Materials

目前以硅为基础的信息技术开始接近电子晶体管的速度和密度所设定的物理极限。为了延续摩尔定律的趋势，人们希望出现量子材料，因为它们可能会将信息处理范式从控制电子输运转变为操纵自旋相互作用，从而消除电荷转移和热量耗散，从而导致更快的速度、更小的设备和更好的能源效率。这种变革性的技术被称为自旋电子学，它需要磁性和半导体特性共存。最近在二维(2D)半导体中发现的本征磁性被认为是一个很有前途的候选系统，其独特的性质与晶格中的电子和自旋相互作用有关，这需要在原子长度尺度上加以理解。本项目旨在利用其空间分辨率(1埃)能够有效识别超微小磁性的透射电子显微镜来研究这类2D材料的磁自旋织构。这项工作将使用布鲁克海文国家实验室世界级的瞬变电磁设备进行，在那里，PI将开发新的研究专业知识并建立长期合作，这将极大地增强克莱姆森大学的研究能力。二维(2D)材料的出现为展示受量子限制限制的奇异物理性质提供了理想的平台，这导致了内在2D磁性的突破性发现，这可能会对量子信息技术产生革命性的影响。为了解决这类材料体系中的电荷、自旋和轨道与晶格的耦合等基础科学问题，利用透射电子显微镜进行原子学表征是必不可少的。本项目的目标是利用基于透射电子显微镜的磁成像技术来探测二维铁磁晶体及其范德华(VDW)异质结构中的磁性自旋织构。这项工作将与布鲁克海文国家实验室(BNL)的研究人员合作进行，该实验室是电子显微镜领域的全球领先者。PI将使用一种结合洛伦兹显微镜和电子全息术的独特工具来识别自旋织构，并阐明它们对具有内在磁序的2D VDW材料的外部物理参数和结构效应的依赖关系。这些发现将提供对电子-自旋-晶格关联的机制的理解，并为新出现的自旋电子学的应用提供实际意义。这一奖学金使该协会能够在克莱姆森大学和BNL之间建立长期的合作关系，这反过来将加强该协会和整个克莱姆森社区的研究活动、专业知识和教育，从而提高南卡罗来纳州的科学竞争力、劳动力发展和经济增长。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The current silicon-based information technologies start to approach the physical limit set by the speed and density of electronic transistors. To continue the trend of Moore's Law, the hope is the emergent quantum materials because they may shift the information processing paradigm from controlling the electronic transport to manipulating the spin interaction, thereby eliminating charge transfer and heat dissipation, leading to higher speed, smaller device, and better energy efficiency. This transformative technology is known as "spintronics", which requires the coexistence of magnetic and semiconducting properties. Recent discovery of intrinsic magnetism in two-dimensional (2D) semiconductors is considered as a promising candidate system, whose unique properties are correlated to the electron and spin interactions within the crystal lattices, which needs to be understood at the atomic length scale. This project aims to investigate the magnetic spin textures in such 2D materials using transmission electron microscopy (TEM) whose spatial resolution (1 angstrom) can effectively identify the ultrasmall magnetic characteristics. This work will be performed using the world-class TEM facilities at Brookhaven National Laboratory, where the PI will develop new research expertise and establish long-term collaborations that can greatly enhance the research capacity of Clemson University.The emergence of two-dimensional (2D) materials offers an ideal platform to display exotic physical properties restricted by the quantum confinement, which leads to the groundbreaking discovery of intrinsic 2D magnetism that may have a transformative impact on quantum information technologies. To address the fundamental science questions regarding the charge, spin, and orbital coupling with the crystal lattice in such material systems, the atomistic characterization using transmission electron microscopy (TEM) is essential. The goal of this project is to probe the magnetic spin textures in 2D ferromagnetic crystals and their van der Waals (vdW) heterostructures using TEM-based magnetic imaging techniques. The work will be performed in partnership with researchers at Brookhaven National Laboratory (BNL), which is a worldwide leader in the field of electron microscopy. The PI will employ a unique toolset combining Lorentz microscopy and electron holography to identify the spin textures and elucidate their dependence of extrinsic physical parameters and structural effects in 2D vdW materials with intrinsic magnetic orders. These findings will provide a mechanistic understanding of electron-spin-lattice correlation underpinning the intrinsic 2D magnetic properties and show practical implications for the emerging spintronics applications. This fellowship allows the PI to establish a long-term collaboration between Clemson University and BNL, which, in turn, will strengthen the research activities, expertise, and education for the PI and the whole Clemson community, and thereby enhance the scientific competitiveness, workforce development, and economic growth of the State of South Carolina.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.