Nanostructured Magnetic Networks

这是对纳米结构磁网络中加工/微观结构/磁性相互关系的系统研究。该项目的目标包括制造一系列不同尺寸和磁性材料的网络，定量评估网络微观结构和拓扑结构，确定不寻常磁性质的物理起源，以及评估网络材料作为磁性记录介质的潜力。网络是使用简单的溅射沉积在纳米结构衬底（纳米通道氧化铝）表面，电子束光刻和自然相分离系统制造的。利用扫描电子显微镜、原子力显微镜和透射电子显微镜对沉积态和退火态进行了定量的微观结构和拓扑表征。通过透射电子显微镜和选定区域电子衍射记录了网络的纳米结构特征（晶体尺寸、晶体织构等）。磁性表征和磁性与网络几何形状和尺寸的相关性是本提案的核心。包括温度相关测量、退火研究、磁成像和铁磁共振在内的多技术方法被用于发展对网络磁畴结构、反转机制和稳定性的理解。这里提出的网络的独特拓扑结构允许详细研究从传统的连续薄膜介质（一维纳米尺度，厚度）过渡到由离散柱、条和点组成的介质（二维或三维纳米尺度）的影响。这一研究项目在教育和人力资源发展领域尤为突出。该计划是多学科的，具有强大的基础和技术组成部分。该项目的研究生和博士后预算涉及固态物理、冶金、薄膜科学、磁性表征、材料加工、微观结构表征和材料选择等方面。纳米结构网络是一种独特的几何结构，由于其小尺寸和新颖的拓扑结构，它表现出不同寻常的潜在有用的磁性行为。纳米结构网络是一种连续的拓扑结构，它可以被描绘成具有高密度孔或孔的薄膜。当孔径、平均孔间距和网络厚度接近纳米尺度时，可以观察到对磁性能的强约束效应（例如，在等效厚度的连续薄膜上，矫顽力增加超过两个数量级）。网络的独特之处在于，它们的维度可以通过改变厚度、孔径和孔隙度在纳米尺度上连续控制。磁网络的性质才刚刚开始被探索。

9713497 Barnard This is a systematic study of processing/microstructure/magnetic property interrelationships in nanostructured magnetic networks. The project objectives include fabrication of a set of networks of varying dimensions and magnetic materials, quantitative assessment of network microstructure and topology, determination of the physical origin of the unusual magnetic properties, and evaluation of the potential of network materials as magnetic recording media. Networks are fabricated using simple sputter deposition onto the surface of nanostructured substrates (nanochannel alumina), e-beam lithography, and naturally phase separating systems. Quantitative microstructural and topological characterization are carried out in both the as-deposited and annealed states using a combination of scanning electron microscopy, atomic force microscopy, and transmission electron microscopy. The nanostructural characteristics (crystallite size, crystallographic texture, etc.) of the networks are documented by transmission electron microscopy and selected area electron diffraction. Magnetic characterization and correlation of magnetic properties with network geometry and dimensions are at the core of this proposal. A multitechnique approach including temperature dependent measurements, annealing studies, magnetic imaging, and ferromagnetic resonance are used to develop an understanding of network magnetic domain structures, reversal mechanisms, and stability. The unique topology of the networks proposed here allows for detailed study of the effects of transitioning from traditional continuous film media (nanoscale in one dimension, the thickness) to media comprised of discrete pillars, bars, and dots (nanoscale in two or three dimensions). This research project is particularly strong in the areas of educational and human resources development. The program is multidisciplinary and has strong fundamental and technological components. Both the graduate stude nt and post-doc budgeted for the project employ aspects of solid state physics, metallurgy, thin film science, magnetic characterization, materials processing, microstructural characterization, and materials selection. %%% Nanostructured networks are a unique geometry which exhibit unusual and potentially useful magnetic behavior associated with their the small dimensions and novel topology. A nanostructured network is a contiguous topology which may be pictured as a thin film with a high density of holes or pores. When the pore size, mean pore separation, and network thickness approach nanoscale dimensions, strong confinement effects on magnetic properties (such as increases in coercivity of more than two orders of magnitude over continuous films of equivalent thickness) are observed. Networks are unique in that their dimensionality can be continuously controlled at the nanometer scale by varying the thickness, pore size, and porosity. The properties of magnetic networks are only beginning to be explored.