High output micromotor using amorphous nanowires and thin film magnets

一般来说，传统电磁电机的输出功率与所用磁性材料的体积成正比。当电机小型化到几毫米见方时，其输出功率约为10微米-米。为了获得更大的输出功率，需要开发一种新的驱动技术。在本研究项目中，我们试图利用磁性纳米线和薄膜磁体来开发一种高输出的电感应器。(1)利用阳极氧化技术制备了高纵横比的磁性纳米线，并将其应用于垂直记录介质。但由于使用了电沉积，它的长度被限制在几微米以内。在本研究中，我们致力于用直流电沉积法制备多个以上的高深宽比纳米线。通过在绝缘层上打孔，即所谓的阻挡层，以及随后的直流电沉积，我们成功地制备了长达90微米的纳米线。它的高宽比超过2000。制作的丝材具有足够的柔韧性，可以应用于执行器。(2)薄膜磁体--高能积薄膜磁体的研制。为了抑制晶体生长，采用溅射法制备了NdDy-Fe-B和Fe薄膜的层状结构。结果表明，Dy元素的加入增强了稀土元素的威胁性，切断了两层之间的交换作用。通过这种方法，厚膜磁体的铺层获得了高的矫直力。(3)执行器利用磁性纳米线和薄膜磁体，提出了一种新的微致动器原理。铝阳极氧化后的纳米线受到薄膜磁体的横向偏置，而纵向交流电场则使纳米线的磁化强度发生逆转。通过这种方式，纳米线可以在横向上振动。

In general, out-put power of conventional electro-magnetic motors is proportional to volume of used magnetic materials. When the motor is miniaturized to the size down to a few mm square, its out-put power is around 10muN-m. To get larger out-put power, a new driving technique is needed to develope. In the present research program, an attempt was made to develope a high output acutuater by using magnetic nanowires and thin film magnets.(1) Magnetic nanowires with high aspect ratioSo far the magnetic nanowire has been fabricated by anodization technique for application to perpendicular recording media. But its length is limited less than a few microns, since acelectrodeposition has been used. In the present investigation, effort was made to apply dc eletrodeposition for fabrication of the nanowire with high aspect ratio more than a few thausands. By making holes in the insulating layr, so called barrier layr, and subsequent application of dc electrodeposition, we fabricated successfuly the nanowire 90 mum long. Its aspect ratio is more than 2000. The fabricated wire is flexible enough to be applied to actuater.(2) Thin film magnetsThin film magnet with high energy product was developed. To restrain the grain growth, layred structue with Nd-Dy-Fe-B and Fe thin film was fabricated by sputtering. It was found that addition of Dy element increases coercivety and cutts off the exchange interaction between both layrs. By this way, high coercivity was obtained with the layred thick film magnet.(3) ActuaterA new principle for micro-actuater was demonstrated using the magnetic nanowires and thin film magnet. The nanowires on the anodized Al substrate was biased in the transverse direction by the thin film magnet and magnetization of the wires was reversed by the longitudinal ac field. By this way, the nanowires can be vibrated in the transeverse direction.