CAREER: Cluster-Assembled Magnetic Nanostructures

[875425] leslie - pelecky .这个CAREER提案的目标是：1)使用一种新的蒸发-冷凝-压实沉积技术制造团簇组装磁性材料；2)将磁性和磁输运性质与样品结构联系起来，以了解无序在磁性中的作用；3)研究从永久磁铁到传感器的应用潜力。一种带气蒸发-冷凝技术被用来形成直径从5 - 50纳米的团簇。这些团簇在高压下被压实，形成纳米颗粒的块状材料。进行了广泛的结构表征，包括x射线衍射，电子显微镜，中子散射和EXAFS。由此产生的纳米结构有两个组成部分：晶体颗粒和颗粒之间的原子，它们统称为界面。当晶粒尺寸较小时，间相占样品的很大一部分（5nm晶粒可达50%），并且是决定样品整体磁性质的重要因素。一系列静态和动态磁性和磁输运测量将确定晶粒和间相的内在特性，以及这两个成分如何相互作用。用标度法研究了多长度尺度上的有序性，阐明了这些体系与其他随机磁性体系（如自旋玻璃、随机各向异性磁体和非晶铁磁体）的异同。这个由两部分组成的教育计划解决了导致学生选择不把科学作为职业的一些因素。将开设两门一学分的课程，为学生进行本科研究做好准备，并培养与科学家和非科学家交流所需的技能。教育项目的第二部分涉及到UNL物理学生协会拓展到林肯的一所低收入小学。本项目解决了团簇组装磁性纳米结构的几个基本问题：1)利用蒸发-冷凝-压实技术制造这些磁性材料；2)它们的磁性和磁输运性质与样品结构的相关性，以解释磁性中的无序作用；3)从永磁体到磁传感器的潜在应用研究。一种新的沉积技术被用来形成直径从5 - 50纳米的簇。这些团簇在高压下被压实，形成纳米颗粒的块状材料。使用团簇作为“构建块”，在定制具有特定特性的磁性纳米结构方面提供了很大的通用性。这些材料的一个独特之处在于，具有非常小颗粒的样品显示出传统块状材料无法实现的磁性。这个项目将确定产生这些非凡特性的机制。这个由两部分组成的教育计划解决了导致学生选择不把科学作为职业的一些因素。将开设两门一学分的课程，为学生进行本科研究做好准备，并培养与科学家和非科学家交流所需的技能。教育项目的第二部分涉及到UNL物理学生协会拓展到林肯市一所低收入的小学

9875425Leslie-PeleckyThe goals of this CAREER proposal are 1) to fabricate cluster-assembled magnetic materials using a novel evaporation-condensation-compaction deposition technique; 2) to correlate magnetic and magnetotransport properties to sample structure to understand the role of disorder in magnetism; and 3) to investigate the potential for applications ranging from permanent magnets to sensors. A gas-entrained evaporation-condensation technique is used to form clusters with diameters from 5 - 50 nm. The clusters are compacted under high pressure to form a nano-grained bulk material. Extensive structural characterization is performed, including x-ray diffraction, electron microscopy, neutron scattering and EXAFS. The resulting nanostructures have two components: crystalline grains, and the atoms between the grains, which are collectively called the interphase. The interphase is a large fraction of the sample when the grain size is small - up to 50% for 5-nm grains - and can be a significant factor in determining overall sample magnetic properties. A range of static and dynamic magnetic and magnetotransport measurements will determine the intrinsic properties of the grains and the interphase, and how the two components interact. Ordering on multiple length scales is investigated using scaling to elucidate the similarities and differences between these systems and other random magnetic systems such as spin glasses, random anisotropy magnets and amorphous ferromagnets.The two-part education plan addresses some of the factors that cause students to choose not to pursue science as a profession. Two one-credit courses will be developed to prepare students for undergraduate research and develop the skills necessary to communicate with scientists and non-scientists. The second part of the education project involves the UNL Society of Physics Students in outreach to a low-income elementary school in Lincoln. %%%This project addresses several fundamental issues in cluster-assembled magnetic nanostructures: 1) fabrication of these magnetic materials using an evaporation-condensation-compaction technique; 2) correlation of their magnetic and magnetotransport properties to sample structure to explain the role of disorder in magnetism; and 3) investigation of their potential applications ranging from permanent magnets to magnetic sensors. A novel deposition technique is used to form clusters with diameters from 5 - 50 nm. The clusters are compacted under high pressure to form a nano-grained bulk material. Using clusters as "building blocks" offers great versatility in tailoring magnetic nanostructures to have specific characteristics. A unique feature of these materials is that samples with very small grains display magnetic properties impossible to achieve with traditional bulk materials. This project will determine the mechanisms responsible for these extraordinary properties.The two-part education plan addresses some of the factors that cause students to choose not to pursue science as a profession. Two one-credit courses will be developed to prepare students for undergraduate research and develop the skills necessary to communicate with scientists and non-scientists. The second part of the education project involves the UNL Society of Physics Students in outreach to a low-income elementary school in Lincoln.***