NER: Synthesis and Characterization of Self-Assembled Nanoscale Magnetic Particles

该资助旨在探索脉冲激光沉积（PLD）技术在不同薄膜基质中，帮助自组织生长具有理想形状、尺寸和浓度的均匀磁性纳米颗粒（岛）。磁性纳米颗粒材料将由单元素（如Fe、Co、Ni等）和多元素合金（如Fe- pt、Sm-Fe-Ti等）组成。基体材料将由非磁性氧化物（如Al2O3和SiO2）和氮化物（如TiN、AlN）组成。通过改变衬底温度、决定到达衬底表面吸附原子数量密度的激光能量密度和环境气体压力，可以控制磁性纳米颗粒的大小、形状和体积分数。本项目开发的自组装纳米复合材料将为磁性测量和分析提供一系列材料。目标是使用先进的微结构技术，如带有原子序数对比的扫描透射电子显微镜（STEM-Z）和带有原子尺寸探针的电子能量损失光谱（EELS），以确定界面的结构以及局部化学成分，以及纳米级构建块与周围环境之间的分离和相互作用的影响。提议的活动的更广泛的影响将是(i)具有窄粒径分布的纳米磁性颗粒的自组装新方法的发展，（ii）对纳米尺度磁性的基本理解，（iii）从原子分辨率z对比图像中三维重建纳米颗粒形状的新技术，以及（iv）纳米技术领域的研究生和本科生的研究和教育计划。

The grant explores development of pulsed laser deposition (PLD) assisted self-organized growth of uniform magnetic nanoparticles (islands) of ideal shape, dimension, and concentration in different thin film matrices. The magnetic nanoparticle materials will be constituted of both single elements (such as Fe, Co, Ni, etc.) and multielemental alloys (such as Fe-Pt, Sm-Fe-Ti, etc.). The matrix materials will be constituted of nonmagnetic oxide (such as Al2O3 and SiO2) and nitride (such as TiN, AlN). The substrate temperature, laser energy density determining the number density of arriving adatoms on substrate surface, and pressure of the gas ambient will be varied to control the size, shape and volume fraction of magnetic nanoparticles. The self-assembled nanocomposites developed in this project will provide a range of materials for magnetic properties measurements and analyses. The goal is to use advanced microstructural techniques such as scanning transmission electron microscopy with atomic number contrast (STEM-Z) and electron energy loss spectroscopy (EELS) with atomic size probe to determine the structures of the interfaces as well as the local chemistries and the effects of segregation and interaction between the nanoscale building blocks and their surroundings.The broader impacts of the proposed activity will be the development of (i) a new method for selfassembly of nanomagnetic particles with narrow particle size distribution, (ii) a fundamental understanding on magnetic properties at the nanoscale, (iii) new techniques for three-dimensional reconstruction of nanoparticle shape from atomic resolution Z-contrast images, and (iv) research and education programs for graduate and undergraduate students in the area of nanotechnology.