Defect-Rich Quasi Two Dimensional Metal Oxides with Strong Ferromagnetism

具有强铁磁性的富缺陷准二维金属氧化物

• 批准号: 2114931
• 负责人: Xudong Wang
• 金额: $ 55万
• 依托单位: University of Wisconsin-Madison
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2114931&HistoricalAwards=false
• 关键词: Defect; Rich; Quasi; Two; Dimensional

Nontechnical DescriptionMaterials that form permanent magnets or are attracted to magnets are called ferromagnetic. Such materials have many uses, ranging from data storage to power systems. However, ferromagnetism is an unusual property that occurs only in a few substances such as iron, nickel, cobalt and their alloys, and some rare earth materials. This project aims to understand how strong ferromagnetism can arise from ultrathin, two-dimensional (2D) materials, that are not magnetic in bulk form. Vacancies, a type of defect arising from “missing” atoms, appear to play a crucial role in stabilizing magnetism in 2D semiconductors. The investigators will perform a combined experimental and theoretical study to determine the concentration of vacancies that can be formed in these nanosheets and quantify how they impact magnetic properties. This research has the potential to realize low-dimensional ferromagnetic materials with a broad range of applications, including memory devices and quantum computing. This project offers opportunities to provide research experiences to underrepresented minority undergraduate and provides education and training on experimental and computation materials research. This project enriches the Informatics Skunkworks to engage undergraduates in research at the interface of data science and materials science and engineering. The research project and results will be integrated into outreach to high school teachers and students.Technical DescriptionThe objective of this project is to understand the formation and stabilization mechanisms of massive cation vacancy concentrations in quasi two-dimensional (2D) transition metal oxides and demonstrate that strong ferromagnetism can be induced in non-ferromagnetic oxides by dimension confinement and point defect engineering. This project is based on an overarching hypothesis that cation vacancies can be created and stabilized at a high level in oxides when their thickness is reduced to the nanometer level, which in turn introduces a strong ferromagnetism to the 2D material. The PIs discovered orders of magnitude enhancement of room temperature ferromagnetism from zinc vacancy-rich 2D ZnO nanosheets. A strong cooperative coupling phenomenon stabilized a vacancy concentration greater than 30% in ZnO nanosheets, enabled by ionic layer epitaxy. The combined experimental and theoretical research project consists of three specific research tasks. Task 1 is a theoretical study to understand the fundamental mechanisms of massive cation vacancy concentration stabilization and associated strong ferromagnetism in 2D oxide lattices. Task 2 is an experimental investigation of zinc vacancy evolution and stabilization mechanisms in ZnO nanosheets to understand the cation vacancy formation and stabilization mechanisms in correlation to the nanoscale thickness, surfaces and grain boundaries. In task 3, the extraordinary magnetic properties rising from the cation vacancies in ultrathin nanosheets are quantified in cerium and manganese oxides, as representative examples to reveal vacancy ordering contribution, and cation vacancy and transition metal moment coupling effects, respectively. Success of this project brings transformative knowledge for the design and synthesis of a new family of ferromagnetic 2D nanomaterials with high magnetization and multi-functionality.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.

形成永久磁铁或被磁体吸引的非技术描述称为铁磁。此类材料有很多用途，从数据存储到电源系统。但是，铁磁是一种异常特性，仅在铁，镍，钴及其合金等几种物质中发生，以及一些稀土材料。该项目的目的是了解超薄的二维（2D）材料如何产生强大的铁磁。空缺是由“缺失”原子引起的一种缺陷，似乎在稳定2D半导体的磁力方面起着至关重要的作用。研究人员将进行一项合并的实验和理论研究，以确定可以在这些纳米片中形成的空位的浓度，并量化它们如何影响磁性。这项研究有可能实现具有广泛应用的低维铁磁材料，包括存储器设备和量子计算。该项目提供了为代表性不足的少数群体本科生提供研究经验的机会，并提供有关实验和计算材料研究的教育和培训。该项目丰富了Informatics Skunkworks，以在数据科学和材料科学与工程界面的研究中吸引本科生。 The research project and results will be integrated into outreach to high school teachers and students.Technical DescriptionThe objective of this project is to understand the formation and stabilization mechanisms of massive cation vacancy concentrations in quasi two-dimensional (2D) transition metal oxides and demonstrate that strong ferromagnetic oxides can be induced in non-ferromagnetic oxides by dimension confinement and point defect engineering.该项目基于一个总体假设，即阳离子空位可以在将其厚度降低到纳米水平时在氧化物中高水平创建和稳定，进而将强力铁磁材料引入2D材料。 PI发现了来自锌空缺富含2D ZnO纳米片的室温铁磁学的数量级。强大的合作偶联现象稳定了ZnO纳米片的空置浓度大于30％，这是由离子层的外观外观启用的。合并的实验和理论研究项目包括三个特定的研究任务。任务1是一项理论研究，旨在了解2D氧化物晶格中大规模阳离子空位浓度稳定和相关的强铁磁性的基本机制。任务2是ZnO纳米片中锌空位演化和稳定机制的实验研究，以了解与纳米级厚度，表面和晶界相关的阳离子空位形成和稳定机制。在任务3中，超薄纳米片的阳离子空位上升起的非凡磁性特性在泥浆和锰氧化物中进行了量化，作为代表性的例子，分别揭示空缺排序的贡献，以及阳离子空位和过渡金属矩偶联效应。该项目的成功为设计和综合具有高磁化和多功能性的新型铁磁纳米材料的设计和综合带来了变革性知识。该奖项反映了NSF的法定任务，并通过使用基金会的知识分子和更广泛的影响审查标准来通过评估来诚实地支持NSF的法定任务。

项目成果

Nucleation Kinetics and Structure Evolution of Quasi-Two-Dimensional ZnO at the Air–Water Interface: An In Situ Time-Resolved Grazing Incidence X-ray Scattering Study

空气-水界面处准二维 ZnO 的成核动力学和结构演化：原位时间分辨掠入射 X 射线散射研究

• DOI: 10.1021/acs.nanolett.2c00300
• 发表时间: 2022
• 期刊: Nano Letters
• 影响因子: 10.8
• 作者: Zhang, Ziyi;Carlos, Corey;Wang, Yizhan;Dong, Yutao;Yin, Xin;German, Lazarus;Berg, Kelvin Jordan;Bu, Wei;Wang, Xudong
• 通讯作者: Wang, Xudong