Exploring 2D Van der Waals Heterostructures with Layered Magnets for Valley-Based Electronics and Optoelectronics

非技术描述：控制磁性是现代信息技术的核心，通常是通过使用另一块磁铁来实现的。这种方法大大限制了用于信息处理的设备的大小。迫切需要开发非磁性方法来控制磁性，以实现更好的信息技术。该项目旨在开发一种新型的纳米厚度的复合磁性材料，其磁性可以通过电场有效地切换。这样的操作更节能，因为它避免了电子设备的加热。这项研究使用原子薄晶体，包括磁性和非磁性半导体，并按设计垂直堆叠它们。研究这些复合材料是为了了解它们的结构特征如何导致磁性能的改善，并为电子学和光电子学中的应用开发器件概念。该项目支持一名研究生的研究和开发。除了研究培训外，学生还通过与康奈尔大学研究、教学和学习整合中心合作，发展大学STEM(科学、技术、工程和数学)学科的其他教学技能。首席研究员正在将最先进的研究概念，如现代光学显微镜纳入一门本科实验室课程，同时还监督针对年轻学生和他们的老师的外展活动。技术描述：近年来发现了一大类单独具有有趣特性的二维材料。将不同的二维材料堆叠起来形成范德华异质结构，为探索新的物理现象和器件概念开辟了前所未有的机会。该项目旨在开发一类新的铁磁半导体，基于单层非磁性半导体之间的磁邻近耦合，例如表现出有趣的山谷相关性质的过渡金属二卤化物，以及层状磁体，如过渡金属三卤化物。该研究将材料制备与光学、结构和输运特性相结合，以实现三个目标：(1)演示和理解层状磁体中磁序的电转换；(2)发展非磁性半导体和具有强磁邻近耦合的层状磁体的异质结，并展示异质结谷特性的电开关；(3)探索电可开关谷相关电子和光电子器件的异质结的输运和光学性质。该项目的结果有可能影响包括自旋电子学和电子谷电子学在内的一系列不同领域，以及提高对低维系统中界面现象的理解。该项目支持一名研究生的科学培训和专业发展，以及各级的教育和推广活动，同时专注于引入最先进的研究概念。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。

Nontechnical description: The control of magnetism, which lies at the heart of modern information technology, is typically achieved by using another magnet. This approach significantly limits the size of devices for information processing. There is a pressing need to develop non-magnetic approaches to control magnetism for better information technology. This project aims to develop a new class of composite magnetic materials of nanometers in thickness, whose magnetic properties can be effectively switched through an electric field. Such an operation is much more energy-efficient since it avoids heating of the electronic device. The research employs atomically thin crystals, including both magnetic and non-magnetic semiconductors, and stacks them vertically by design. These composite materials are studied to understand how their structural characteristics may lead to improved magnetic properties, and to develop device concepts for applications in electronics and optoelectronics. This project supports the research and development of one graduate student. In addition to training in research, the student develops other skills for teaching in the STEM (Science, Technology, Engineering, and Mathematics) disciplines at the university level by working with the Cornell University Center for the Integration of Research, Teaching, and Learning. The Principal Investigator is incorporating state-of-the-art research concepts such as modern optical microscopy into an undergraduate lab course, while also overseeing outreach activities targeting younger students and their teachers.Technical description: A large family of two-dimensional materials that possess interesting properties individually has been discovered in recent years. Stacking different two-dimensional materials to form van der Waals heterostructures has opened up unprecedented opportunities for exploring new physical phenomena and device concepts. This project aims to develop a new class of ferromagnetic semiconductors based on magnetic proximity coupling between single-layer non-magnetic semiconductors, such as transition metal dichalcogenides that exhibit interesting valley-dependent properties, and layered magnets, such as transition metal trihalides. The research combines materials fabrication and optical, structural and transport characterization to achieve three objectives: (1) Demonstrate and understand electrical switching of magnetic order in layered magnets; (2) Develop heterostructures of non-magnetic semiconductors and layered magnets with strong magnetic proximity coupling and demonstrate electrical switching of the valley properties of the heterostructures; and (3) Explore the transport and optical properties of the heterostructures for electrically switchable valley-dependent electronic and optoelectronic devices. The results of this project have the potential to impact a range of diverse fields including spintronics and valleytronics, as well as improve understanding of interfacial phenomena in low-dimensional systems. The project supports the scientific training and professional development of one graduate student, as well as education and outreach activities at all levels, while focusing on introduction of state-of-the-art research concepts.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.