Understanding and Controlling Magnetic Two-Dimensional Crystals

磁性材料在通信、计算和先进电子领域得到了广泛的应用。由于一种叫做自旋的量子特性，电子具有固有的磁性。块状材料中的磁性是由这些沿同一方向取向的自旋耦合产生的。本研究项目探索了一类基于二维（2D）材料的新型超薄磁铁的特性。对于这种原子级薄的材料，电子自旋的取向对局部环境和外界刺激非常敏感。这就产生了传统磁铁无法实现的新的物理现象和设备功能。本项目将研究吸附分子、相邻层和机械应变对二维磁体性能的影响。我们的目标是学习如何控制它们的特性，从而有可能创造出按需的物理特性和具有超紧凑外形和新颖功能的设备。高中、本科和研究生将在二维材料制造和表征方面接受丰富的专业知识培训。因此，该项目将有助于为美国的量子信息科学和技术准备未来的劳动力，PI还将通过当地的教育活动提高公众对量子技术的素养。磁性二维材料为量子磁性研究提供了理想的凝聚态材料平台，并且对二维磁体的控制可能为物质的新量子相和超薄磁电和磁光器件提供前所未有的机会。二维铁磁体的广泛应用前景取决于其磁性能的多样性，但仍受到现状的阻碍：只有少数二维铁磁体被明确发现，其性质的多样性有限。通过设计实验来精细地修改二维磁体的结构、电子和化学特性，该项目旨在揭示二维磁性对量子材料基本物理参数的复杂依赖。基于这些基本的理解，重要的工程方法可以开发出“设计”或“按需”的磁性量子材料特性。主要的研究方法包括通过接触材料、吸附化学物质和应变晶格等实际影响因素对二维磁体进行控制，以及通过扫描磁圆二色性和磁反射光谱等一系列显微镜和光谱学来探测改变的性质。了解与这些影响因素相关的二维磁性，并由此开发工程方法，可能会促进对二维磁体的前所未有的操纵，从而改变磁性量子材料的格局，并实现破坏性的自旋电子和量子技术。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。

Non-technical DescriptionMagnetic materials have found widespread applications in communications, computing, and advanced electronics. Electrons possess have intrinsic magnetism, due to a quantum property called spin. Magnetism in a bulk materials arises from the coupling of these spins to be oriented along the same direction. This research project explores the properties of a new class of ultrathin magnets based on two-dimensional (2D) materials. For such atomically thin materials, the orientations of electron spins are very sensitive to the local environment and external stimulus. This gives rise to new physical phenomena and device functionality not possible from conventional magnets. This project will study the effects of adsorbed molecules, adjacent layers, and mechanical strain on the properties of 2D magnets. The goal is to learn how to control their properties, potentially leading to the creation of on-demand physical properties and devices with ultracompact form factors and novel functionality. High school, undergraduate, and graduate students will be trained with a rich set of expertise in 2D materials fabrication and characterization. This project will therefore help to prepare the future workforce for the quantum information science and technologies in the U.S. The PI will also raise the public literacy of quantum technologies through local educational activities.Technical DescriptionMagnetic 2D materials provide an ideal condensed matter platform for the study of quantum magnetism, and the control of 2D magnets potentially unlocks unprecedented opportunities for new quantum phases of matter and ultrathin magnetoelectric and magneto-optical devices. The breadth of application prospects of 2D magnets hinges on the diversity of magnetic properties but remains hindered by the status quo: only a small number of 2D ferromagnets have been unambiguously discovered, with a limited variety of properties. Through designing experiments to finely modify the structural, electronic, and chemical characteristics of 2D magnets, this project seeks to unravel the complex dependence of 2D magnetism on the basic physical parameters of quantum materials. Based on these fundamental understandings, vital engineering approaches can be developed to create “designer” or “on-demand” magnetic quantum materials properties. The main research approaches include controlling 2D magnets by subjecting them to practical influencing factors such as contacting materials, adsorbed chemicals, and strained lattices and probing the altered properties by a range of microscopies and spectroscopies such as scanning magnetic circular dichroism and the magneto-reflectance spectroscopy. Understanding 2D magnetism in relation to these influencing factors and developing engineering approaches therefrom could prompt unprecedented manipulation of 2D magnets, thereby transforming the magnetic quantum material landscape and enabling disruptive spintronic and quantum technologies.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.