Magnetism, Spin Texture and Magnetotransport Phenomena in Covalent 2D Magnets

非技术描述本研究项目探索一类只有几个原子层厚度的新型磁性材料的性质。传统的二维（2D）材料，如石墨烯，是由原子层彼此弱结合而成的。这里要研究的材料有额外的原子，它们以共价键连接到各个层上，就像胶水一样把原子层粘在一起，改变它们的行为方式。这些二维磁体的奇异特性使它们在基础科学研究和实际应用中特别有趣。最终目标是通过材料设计、电场和物理应变来控制它们的特性。该项目将有助于为以超快速度和低功耗运行的新型存储器和逻辑器件铺平道路。这种设备可能会影响传感和量子信息处理等应用。调查人员将通过指导和有针对性的招募，努力扩大代表性不足群体的参与。布法罗大学和布林茅尔学院之间的合作伙伴关系将使女本科生能够通过暑期交流和在国家机构的研究经验参与其中。该研究项目将研究人员的专业知识共生地结合起来，合成新的自插层共价二维磁体和磁体/半导体异质结构，并探索和调整新兴的基于自旋的拓扑和磁输运现象。项目目标是：(1)通过化学气相沉积和外延生长高质量、大面积的共价二维磁体及相关异质结构；(2)了解实空间自旋织构和动量空间Berry曲率的作用机制，它们与自插层阳离子浓度的相关性，以及它们的缠结对电载流子输运的影响；(3)通过电门控、应变和外来离子嵌入实现对实动量空间中基于自旋的拓扑现象的主动控制。通过改变这些共价二维磁体中自插层阳离子的浓度以及它们与不同vdW模板的相互作用，可以实现丰富的相，这为材料设计提供了广阔的参数空间，可以赋予现有磁性材料无法实现的新自旋特性。该项目将推进对这些材料的基本认识，破译缠绕自旋结构和Berry曲率对磁输运的影响，并将材料库扩展到具有高居里温度的化学稳定的共价二维磁体。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 DescriptionThis research project explores the properties of a new class of magnetic materials with thicknesses of only a few-atomic layers. Conventional two-dimensional (2D) materials like graphene are made of atomic layers weakly bound to each other. The materials to be studied here have extra atoms that are covalently bonded to the individual layers, acting like a glue to hold the atomic layers together and change the way they behave. The exotic properties of these 2D magnets make them particularly interesting for fundamental scientific research and practical applications. The ultimate goal is to control their properties through material design, electric fields, and physical strain. This project will help to pave the way for novel memory and logic devices operating at ultrafast speed with low power consumption. Such devices could impact applications such as sensing and quantum information processing. The investigators will strive to broaden the participation of underrepresented groups by mentoring and targeted recruiting. The partnership between the University at Buffalo and Bryn Mawr College will enable the participation of female undergraduate students through summer exchange and research experiences at national facilities.Technical DescriptionThis research program symbiotically combines the expertise of the investigators to synthesize new self-intercalated covalent 2D magnets and magnet/semiconductor heterostructures, and to explore and tune emergent spin-based topological and magnetotransport phenomena. The project objectives are (1) to grow high-quality, large area covalent 2D magnets and related heterostructures by chemical vapor deposition and dative epitaxy; (2) understand the mechanisms of real space spin textures and momentum space Berry curvature, their correlation with self-intercalated cation concentration, and the effects of their intertwining on electrical carrier transport; and (3) achieve active control of spin-based topological phenomena in real and momentum space by electric gating, strain, and foreign ion intercalation. The rich phases achievable by varying the concentration of self-intercalated cations in these covalent 2D magnets and their interactions with different vdW templates provide broad material design parameter space that could bestow new spin properties unattainable in existing magnetic materials. This project will advance the fundamental understanding of these materials, decipher the effects of intertwined spin structures and Berry curvature on magnetotransport, and expand the library of materials to chemically stable covalent 2D magnets with a high Curie temperature.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.