Isolated and Collective Magnetic Phenomena in Metallic Nanocrystals and Their Superlattices

金属纳米晶体及其超晶格中的孤立和集体磁现象

• 批准号: 0203069
• 负责人: Kannan Krishnan
• 金额: $ 29.48万
• 依托单位: University of Washington
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-07-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0203069&HistoricalAwards=false
• 关键词: Isolated; Collective; Magnetic; Phenomena; Metallic

The research is directed at the synthesis, characterization and assembly of passivated,colloidal nanocrystals of metals into ordered superlattices with the fundamental goal ofunderstanding the evolution of their static and dynamic magnetic behavior as a functionof nanocrystal size and shape, superlattice dimensionality, organizational symmetry andinterparticle interactions. The objective of the work is to use magnetometry methods to get a deeper understanding of the magnetic metrology of nanoscale structures. The study will provide fundamental mechanisms of magnetic reversal with emphasis on the role of finite size and interaction effects as well as the origin of dipolar ferromagnetism, in the absence of interparticle exchange interactions. The study emphasizes on the entropy-driven self-assembly and template-assisted crystallization processes for the synthesis of large-area (mm size) superlattices along with systematic structural and chemical characterization using electron and photon probes. Newly emerging MEMS based metrology methods and electron holography on the nanocrystal samples will be studied through collaborative work.The fundamental goal is a thorough understanding, prediction and control of cooperativemagnetic behavior over different length scales and time signatures in artificiallytailored solids. In addition, the work will provide solutions to fundamental questions associated with magnetic reversal. The research has broad technological implications for it will contribute to the development of the ultimate magnetic recording media, i.e. single-particle per bit recording as well as in MEMS technology.

该研究旨在将金属钝化胶体纳米晶体合成、表征和组装成有序超晶格，其基本目标是了解其静态和动态磁行为随纳米晶体尺寸和形状、超晶格维度、组织对称性和颗粒间相互作用的演变。这项工作的目的是利用磁力测量方法来更深入地了解纳米级结构的磁计量。该研究将提供磁反转的基本机制，重点是在没有粒子间交换相互作用的情况下，有限尺寸和相互作用效应的作用以及偶极铁磁性的起源。该研究强调用于合成大面积（毫米尺寸）超晶格的熵驱动自组装和模板辅助结晶过程，以及使用电子和光子探针进行系统结构和化学表征。新兴的基于 MEMS 的计量方法和纳米晶体样品上的电子全息术将通过协作进行研究。基本目标是彻底理解、预测和控制人工定制固体中不同长度尺度和时间特征的协作磁行为。此外，这项工作还将为与磁反转相关的基本问题提供解决方案。该研究具有广泛的技术意义，因为它将有助于最终磁记录介质（即单粒子每比特记录）以及 MEMS 技术的开发。