Two-Dimensional Nanosheets of Magnetic Lanthanide Chalcogenides

在化学系大分子、超分子和纳米化学项目的支持下，乔治城大学的Sarah Stoll教授将开发具有有用磁性的新型二维材料的合成路线。该项目侧重于具有自然分层结构的材料，层内具有强共价键，层间具有弱相互作用，类似于石墨。对结构和纳米片厚度如何决定磁耦合和方向的更深入的基本理解将是设计利用电子和磁性的新器件的关键，即自旋电子学。该项目将为研究生和本科生提供研究训练。将为当地一所女子高中发展和改编一个以环境化学和伦理问题为重点的互动式讲习班。研究将集中在三种镧系（Ln）材料，它们在结构各向异性、层间键合、磁取向和电子导电性方面系统地变化。第一个家族是三碲化物，LnTe3，它是范德华层状的XY磁体，其中的矩位于薄片的平面上。各向异性稍微小一点的是二碲化物，LnTe2，离子层状的Ising磁体，其磁矩垂直于薄片的平面。最后，第三族是各向同性的单硫属化合物，如EuTe；这些是海森堡的三维磁性半导体。所开发的合成方法对扩大二维材料的合成范围具有重要意义。这些材料表现出广泛的特性，其进一步的研究可以扩展其在下一代器件中的应用。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。

With the support of the Macromolecular, Supramolecular and Nanochemistry Program in the Division of Chemistry, Professor Sarah Stoll of Georgetown University will develop synthetic routes to novel two-dimensional materials with useful magnetic properties. This project focuses on materials with structures that are naturally layered, with strong covalent bonds within the layer and weak interactions between layers, similar to graphite. A deeper fundamental understanding of how structure and nanosheet thickness determine magnetic coupling and orientation will be key for designing new devices that take advantage of both electronic and magnetic properties, i.e. spintronics. This project will provide research training to graduate and undergraduate students. An interactive workshop that focuses on environmental chemistry and ethics issues will be developed and adapted for a local girls high school. The investigation will focus on three classes of lanthanide (Ln) materials that vary systematically in structural anisotropy, inter-layer bonding, magnetic orientation and electronic conductivity. The first family are the tritellurides, LnTe3, which are van der Waals layered XY magnets in which moment is in the plane of the sheets. Slightly less anisotropic are the ditellurides, LnTe2, ionic-layered Ising magnets in which moment is perpendicular to the plane of the sheets. Finally, the third family are the isotropic monochalcogenides such as EuTe; these are Heisenberg, three-dimensional magnetic semiconductors. The synthetic methods developed will be important for expanding the synthetic range of two-dimensional materials. These materials exhibit a wide range of properties whose further study can extend their utility for next-generation devices.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.