US Ireland Research and Development Partnership: Spin and valley interactions in intrinsic and magnetic two dimensional transition metal dichalcogenides for novel devices

二维过渡金属二卤化物(2DTMD)是探索自旋和谷基相互作用的理想平台，这些相互作用将构成自旋电子学和电子电子器件的基础。在这个项目中，来自美国、爱尔兰共和国(ROI)和北爱尔兰(NI)的研究人员提议研究本征和磁性掺杂的2D TMD的基本性质，如相位和自旋相干、谷间散射和磁性。每一家PI都将通过美国爱尔兰研发伙伴计划得到各自资助机构的支持。研究团队是跨学科的，具有互补的专业知识。NI小组将使用最先进的理论方法进行多尺度建模，以预测新的性质，并提供对实验工作的基本理解。ROI小组将提供多尺度表征，并开发新的扫描透射电子显微镜方法，以同时获得关于原子和磁性结构的信息。该美国团队将研究新的合成方法来获得磁性2D材料，并进行量子输运测量，以阐明基本的自旋和谷间散射机制。合作研究将通过组建一个跨学科团队来实现协同效应，该团队将致力于2D材料中的自旋和山谷物理，以实现令人兴奋的科学发现。拟议项目的教育和培训活动将补充拟议项目的科学影响。来自美国、爱尔兰和北爱尔兰的研究生将受益于该项目的科学和教育部分。这种合作将导致培养高度参与、全球联网的研究生，他们拥有在国际和国家实验室环境中经验丰富的跨学科知识。这些学生将从国际交流中受益，通过发展超出其核心博士论文主题专业知识的新技能。此外，有重点的外展活动将包括吸引高中生以及初中和高中教师熟悉材料科学，并通过组织实验室参观、设计动手演示和及时发布新闻稿来吸引公众。这项建议的主要目标是在以下方面提供新的见解：(I)极稀磁(即本征)或弱磁有序体系中自旋和山谷与磁性杂质的基本相互作用；(Ii)2D半导体在高磁有序体系中的铁磁性及其对自旋极化和连贯性的影响。从该项目中获得的新知识将对实现未来基于2D TMD的自旋电子学和电动势电子学装置起到补充作用。此外，在2D半导体中，电掺杂仍然是一个悬而未决的问题，预计这项研究的结果将解决有关热力学浓度限制以及杂质对电子和磁性的影响等关键的基本问题。这些性质将通过量子输运和霍尔效应测量来研究，以获得关于非磁性材料弱局域化的信息。关于磁性样品中自旋极化输运的信息将通过平面内磁场的磁阻测量来获得。期望该研究能为新的基础知识奠定基础，并探索在实验上实现二维磁性TMD用于制造自旋电子器件和微电子器件的可行性。美国和爱尔兰的这一伙伴关系将提供一个框架，在理论和实验上进行合作，以实现新的2D材料特性及其在设备应用中的潜在协同效应。

Two dimensional transition metal dichalcogenides (2D TMDs) are the ideal platform for exploration of fundamental spin and valley interactions that will form the foundation of spintronic and valleytronic devices. In this project, researchers from the United States, Republic of Ireland (ROI), and Northern Ireland (NI) propose to study fundamental properties, such as phase and spin coherences, inter-valley scattering, and magnetism in intrinsic and magnetically doped 2D TMDs. Each PI will be supported by their respective funding agencies through the US Ireland R & D Partnership Program. The Research Team is interdisciplinary with complementary expertise. The NI group will carry out multi-scale modeling using state-of-the-art theoretical methods to predict new properties as well as provide fundamental understanding of the experimental work. The ROI group will provide multi-scale characterization and develop new scanning transmission electron microscopy methods to simultaneously obtain information about atomic and magnetic structures. The US group will investigate new synthesis methods to obtain magnetic 2D materials and perform quantum transport measurements to elucidate fundamental spin and inter-valley scattering mechanisms. The collaborative research will lead to realization of synergies through formation of an interdisciplinary team who will work on spin and valley physics in 2D materials to enable exciting scientific discoveries. The educational and training activities of the proposed project will complement the scientific impact of the proposed project. The graduate students from the US, Ireland, and Northern Ireland will benefit from the scientific and educational components of the program. This collaboration will result in developing highly engaged, globally networked graduate students with interdisciplinary knowledge experienced in international and national laboratory environments. The students will benefit from international exchanges by developing new skills beyond the expertise of their core doctoral thesis topics. Additionally, focused outreach activities will involve engaging high school students as well as middle and high school teachers to be familiarized with materials science as well as engaging public by organizing laboratory tours, designing hands-on demonstrations, and issuing timely press releases.The main goal of this proposal is to provide new insights in: (i) fundamental interactions of spin and valley with magnetic impurities in the very dilute (i.e. intrinsic) or weak magnetic ordering regime; and (ii) ferromagnetism in 2D semiconductors in the high magnetic ordering regime and its influence on spin polarization and coherence. The new knowledge obtained from this project will be complementary in realizing future spintronics and valleytronics devices based on 2D TMDs. In addition, electrical doping remains an unresolved question in 2D semiconductors and it is expected the outcome of this research will address key fundamental questions regarding thermodynamic concentration limit and influence of impurities on electronic and magnetic properties. These properties will be investigated by quantum transport and Hall Effect measurements to obtain information about weak localization for the non-magnetic materials. Information about spin-polarized transport in magnetic samples will be obtained using magneto-resistance measurements with in-plane magnetic fields. It is expected that the research will generate the foundation of new fundamental knowledge and investigate the feasibility of experimentally realizing 2D magnetic TMDs for fabrication of spintronic and valleytronic devices. This US-Ireland partnership will provide a framework to collaborate theoretically and experimentally for realizing new 2D materials properties and thier potential synergies for device applications.