Two-Dimensional Nanosheets of Magnetic Lanthanide Chalcogenides

在化学系大分子、超分子和纳米化学计划的支持下，乔治敦大学的莎拉·斯托尔教授将开发具有有用磁性的新型二维材料的合成路线。该项目专注于具有自然分层结构的材料，层内具有较强的共价键，而层之间的相互作用较弱，类似于石墨。对结构和纳米片厚度如何决定磁耦合和取向的更深层次的基本理解将是设计同时利用电子和磁性的新器件(即自旋电子学)的关键。该项目将为研究生和本科生提供研究培训。将为当地一所女子高中开发并改编一个以环境化学和伦理问题为重点的互动讲习班。研究的重点将集中在结构各向异性、层间键合、磁取向和电子导电性方面存在系统差异的三类稀土(Ln)材料。第一类是三碲化物，LnTe3，它是范德华层状XY磁体，其中的力矩在薄片的平面上。各向异性稍弱的是二碲化物，LnTe2，离子层状伊辛磁体，其中的力矩垂直于薄片的平面。最后，第三个家族是各向同性的单醇化合物，如EuTe；这些是海森堡，三维磁性半导体。所开发的合成方法将对扩大二维材料的合成范围具有重要意义。这些材料展示了广泛的特性，进一步的研究可以将它们扩展到下一代设备。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。

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.