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

非技术性描述：磁控制是现代信息技术的核心，通常通过使用另一个磁体来实现。这种方法显著地限制了用于信息处理的设备的尺寸。迫切需要开发非磁性方法来控制磁性，以改善信息技术。该项目旨在开发一种新型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。这样的操作更加节能，因为它避免了电子设备的加热。该研究采用原子级薄的晶体，包括磁性和非磁性半导体，并通过设计将它们垂直堆叠。研究这些复合材料是为了了解它们的结构特性如何改善磁性能，并开发用于电子和光电子应用的器件概念。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，教学和学习一体化中心合作，培养大学一级STEM（科学，技术，工程和数学）学科的其他教学技能。首席研究员将现代光学显微镜等最先进的研究概念融入本科生实验室课程，同时监督针对年轻学生及其教师的外联活动。技术说明：近年来发现了一大系列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货车范德华异质结构，为探索新的物理现象和器件概念开辟了前所未有的机会。该项目旨在开发一种新的铁磁半导体，其基于单层非磁性半导体（如表现出有趣的谷依赖性的过渡金属二硫属化物）和层状磁体（如过渡金属三卤化物）之间的磁性邻近耦合。本研究将材料制备与光学、结构和输运表征相结合，以实现三个目标：（1）演示和理解层状磁体中磁序的电开关;（2）开发具有强磁邻近耦合的非磁性半导体和层状磁体的异质结构，并演示异质结构的谷特性的电开关;（3）开发具有强磁邻近耦合的非磁性半导体和层状磁体的异质结构。（3）探索异质结构的输运和光学性质，用于电可切换的谷依赖电子和光电子器件。该项目的结果有可能影响一系列不同的领域，包括自旋电子学和谷电子学，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，以及各级教育和推广活动，同时专注于引进最先进的研究概念。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。

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.