CAREER: Cluster-Assembled Magnetic Nanostructures

Leslie-Pelecky这个职业计划的目标是：1）使用一种新的蒸发-冷凝-压实沉积技术制造团簇组装的磁性材料; 2）将磁性和磁输运性质与样品结构相关联，以了解无序在磁性中的作用; 3）研究从永磁体到传感器的应用潜力。 使用气体夹带蒸发-冷凝技术形成直径为5 - 50 nm的团簇。 簇在高压下被压实以形成纳米晶粒的块体材料。 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：晶粒和晶粒之间的原子，统称为界面。 当晶粒尺寸很小时，界面相占样品的很大一部分-对于5 nm晶粒高达50%-并且可以是确定整体样品磁性的重要因素。 一系列静态和动态的磁性和磁输运测量将确定晶粒和界面的固有特性，以及这两种成分如何相互作用。 在多个长度尺度上的有序性研究使用缩放来阐明这些系统与其他随机磁系统（如自旋玻璃、随机各向异性磁体和非晶铁磁体）之间的相似性和差异性。两部分教育计划解决了导致学生选择不追求科学作为职业的一些因素。 将开发两个一学分的课程，为学生的本科研究做好准备，并培养与科学家和非科学家沟通所需的技能。 教育项目的第二部分涉及UNL物理学生协会在推广到林肯的低收入小学。 该项目解决了簇组装磁性纳米结构中的几个基本问题：1）使用蒸发-冷凝-压缩技术制造这些磁性材料; 2）将其磁性和磁输运性质与样品结构相关联，以解释磁性中的无序作用; 3）调查其潜在应用，从永磁体到磁传感器。 一种新的沉积技术用于形成直径为5 - 50 nm的团簇。 簇在高压下被压实以形成纳米晶粒的块体材料。 使用簇作为“构建块”在定制磁性纳米结构以具有特定特性方面提供了很大的通用性。 这些材料的一个独特之处在于，具有非常小晶粒的样品显示出传统块状材料无法实现的磁性。 这个项目将确定这些特殊性质的机制，两部分的教育计划解决了一些导致学生选择不追求科学作为一种职业的因素。 将开发两个一学分的课程，为学生的本科研究做好准备，并培养与科学家和非科学家沟通所需的技能。 教育项目的第二部分涉及UNL物理学生协会在推广到林肯的低收入小学。*

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.***