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

目前基于硅的信息技术开始接近由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，希望是新兴的量子材料，因为它们可能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散热，从而实现更高的速度，更小的设备和更好的能源效率。这种革命性的技术被称为“自旋电子学”，它需要磁性和半导体特性的共存。最近在二维半导体中发现的本征磁性被认为是一个有前途的候选系统，其独特的性质与晶格内的电子和自旋相互作用有关，需要在原子长度尺度上理解。本项目旨在利用空间分辨率为1埃的透射电子显微镜（TEM）研究这种二维材料的磁自旋织构，透射电子显微镜可以有效地识别其超小磁特性。这项工作将在布鲁克海文国家实验室使用世界一流的TEM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，从而大大提高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的奇异物理特性提供了一个理想的平台，这导致了二维磁性的突破性发现，这可能对量子信息技术产生变革性影响。为了解决这些材料系统中电荷、自旋和轨道与晶格耦合的基本科学问题，使用透射电子显微镜（TEM）进行原子表征是必不可少的。本项目的目标是利用基于tem的磁成像技术探测二维铁磁晶体及其范德华（vdW）异质结构中的磁自旋结构。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导者。PI将采用结合洛伦兹显微镜和电子全息术的独特工具集来识别自旋纹理，并阐明它们对具有固有磁序的二维vdW材料的外在物理参数和结构效应的依赖。这些发现将提供对电子-自旋-晶格相关性的机制理解，支持固有的二维磁性，并对新兴的自旋电子学应用显示出实际意义。该奖学金允许PI在克莱姆森大学和BNL之间建立长期合作，这反过来将加强PI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。

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.