Nanostructured Magnetic Network

9615026巴纳德已经开发了一种简单的方法来制备具有独特和有用的磁性能的新型纳米结构磁‘网络’。这种网络的不同寻常之处在于，它们的维度可以在纳米尺度上连续控制，允许探索从零维‘点’到一维多孔网络再到二维薄膜(以及中等尺寸的拓扑结构)的受限几何图形，具体取决于衬底纳米结构和网络厚度。在对铁网络的初步研究中，观察到了矫顽力的显著增强(比等效薄膜的值高出两个数量级)，这是将铁限制在临界尺寸在几十纳米范围内的网络拓扑的直接结果。在这项研究计划中，将评估网络材料和衬底的纳米结构的作用。将对不同饱和磁化强度的铁磁体进行比较研究，以确定网络的强形状各向异性是否是矫顽力增强的主要机制。纳米结构衬底的拓扑结构对沉积网络的磁性的影响将使用具有比商业上可用的更小的孔径和更多的可变孔隙率的多孔性衬底来研究。这部分工作将通过阳极氧化单晶硅晶片来进行。电化学工艺参数将被用来独立控制孔径和排列以及孔隙率。磁特性的目的是了解磁化(和磁化反转)过程以及磁畴结构，将使用温度和时间相关的滞后研究和磁力显微镜进行。网络的精确尺寸和它们的结晶学可以通过透射电子显微镜确定。在下一代记录介质的开发背景下，非常薄的、磁硬的材料的简单制造是重要的。正在研究的独特网络拓扑具有重要的技术意义。例如，一个特别困难的挑战是当使记录头非常接近存储介质时遇到的限制问题。传统的薄膜介质通常通过机械或化学方法粗化，以最大限度地减少这一问题。网络独特的表面形貌应该会在不进行进一步处理的情况下产生较低的粘附值，这将使飞行高度更低，记录密度更高。***

9615026 Barnard A simple method has been developed for fabrication of novel nanostructured magnetic 'networks' which exhibit unique and useful magnetic properties. The networks are highly unusual in that their dimensionality can be controlled continuously at the nanometer scale allowing for exploration of confined geometries ranging from zero dimensional 'dots' to one dimensional porous networks to two dimensional films (as well as topologies with intermediate dimensions) depending on substrate nanostructure and network thickness. In preliminary studies on iron networks, dramatic enhancements in coercivity have been observed (two orders of magnitude higher than the equivalent thin film value) which are a direct result of the confinement of the iron to a network topology with critical dimensions in the range of tens of nanometers. In this research program the role of both the network material and the nanostructure of the substrate will be assessed. Comparative studies of ferromagnets with differing saturation magnetizations will be carried out to determine whether the strong shape anisotropy of the network is the primary mechanism of coercivity enhancement. The effect of the topology of the nanostructured substrate on magnetic properties of the deposited network will be studied using porous substrates with smaller pore diameters and more variable porosity than is available commercially. This part of the work will be carried out by anodically oxidizing single crystal silicon wafers. Electrochemical process parameters will be used to independently control pore diameter and arrangement as well as porosity. Magnetic characterization aimed at understanding the magnetization (and magnetization reversal) process along with the magnetic domain structure will be carried out using temperature and time dependent hysteresis studies and magnetic force microscopy. Precise dimensions of the networks and their crystallography be determined by transmission electron mic roscopy. %%% The simple fabrication of very thin, magnetically 'hard' materials is important in the context of the development of the next generation recording media. The unique network topology under study has important technological implications. For example, a particularly difficult challenge is the striction problem encountered when flying a recording head very close to the storage media. Conventional thin film media are typically roughened by mechanical or chemical means to minimize this problem. The unique surface topography of the networks should give rise to low values of stiction without further processing which will enable lower flying heights and higher recording densities. ***