【作者】 苗秀娟；

【导师】 王学凤；

【作者基本信息】 吉林大学 ， 凝聚态物理， 2008， 硕士

【摘要】 具有人为形状缺陷的图案化薄膜介质是近年来磁存储领域研究的热点,缺陷的存在改变了磁体的磁化反转模式,磁滞回线的形状以及剩磁态等,含有扇形缺口的圆形磁体被认为是对几何圆形磁体的结构改进。研究具有一定形状缺陷的小磁性单元不仅能促进磁存储和磁性传感器等领域的发展,而且能够丰富和完善微磁学理论。本文选择多晶Co纳米磁体作为研究对象,依据实验结果,利用微磁学有限差分的方法系统研究了具有不同扇形缺口的盘状、环状磁体的磁化反转过程。得到结果如下:磁体的形状各向异性对磁化反转过程的影响是最主要的,磁体的剩磁态磁矩分布还强烈地依赖于外场的方向,磁体的直径和厚度对于磁体的剩磁和矫顽力有很大的影响。此外对于环状磁体阵列来说,近邻磁体单元之间的静磁耦合作用对于磁体的回线的形状没有明显的影响,但对磁体单元的剩磁态有一定的影响。更多还原

【Abstract】 Nowadays is information age, magnetic store has been the most capital instrument in the storage of messages. As the deal of digital information which people attend to steps up constantly, people bring up higher request about storage capacity and performance continuously. That how to increase the magnetic store domain density and abridge the response time of read/write is the problem that schoolers who work at magnetic material have to resolve all the time.As a memory media, nanomagnetic thin film have expansive applicatives for high-density recording devices、MRAM and magnetic sensors. the circular element is an ideal candidate which can be packed closely for high density magnetic recording applications. However, for the circular elements, it is difficult to control the remanent state magnetic rotation directions, i.e., clockwise or counterclockwise directions, for information storage applications. The inductiveness of artificial defects in the circular element changed the magnetization reversal pattern and remanent states of magnetics, which is a improve for the circular geometry. While it make the reverse magnetization process to be controlled easily. In resont years, the study on the circular magnetics which contain figurate defects have been being the hot spots.Before these technologys become products, the micromagnetic study on patterned thin film media with artificial defects is very necessary, which not only make us profound grasp the magnetization reversal mechanisms, but also provide beneficial guidance how to improve the performance of magnetic recording. In this paper, remanent states and magnetization reversal for polycrystalline Co slotted-disks and slotted-rings have been investigated using OOMMF micromagnetic calculated shoftware, with different combinations of diameter、slotted angle(α)、thickness and applied field directions. Our results as follows:(1) The 400-nm-diameter Co slotted disks were simulated. Different combinations of disk thickness and slot angles were studied using orthogonal applied field directions (perpendicular and parallel to the slot angle (α)). We found that: the shape anisotropy has great impact on magnetization reversal, while the applied field directions have effect on the magnetic hysteresis and remanent states: When the applied field was perpendicular to the slot direction, the remanent states of all the magnetic elements are Flux-closure configuration, the coercivity, remanent magnetism degrade with the accession in thinkness of disks, or the minishing of sector chip. For the parallel direction applied field, the remanent magnetization of slotted disks degrade with the increase of thinkness and sector chip of magnets, while the variety in coercivity are complicate.(2) The remanent state and magnetization revesal of 30-nm-thick Co slotted rings were simulated individually and in 2×2 arrays with different interelement distances, the field was orthogonal directions too. We found that: the shape anisotropy and the directions of applied field have great effects on the remanent state of the slotted-rings, no matter how the rings arrange (individually or in 2×2 arrays). The distribution of magnetic moment and magnetic rotation directions of the remanent state were decide by the direction of applied field: When the field applied perpendicular to the slots, the remanent states of all the magnetic elements are Flux-closure configuration. The width of annular magnetic affects the remanent magnetization and coercivity too.In 2×2 arrays of slotted rings with the thinkness of 30nm [OD/ID (nm): 300/50, ], The interelement distance have effects on the shape of hysteresis, the distribution of magnetization vector in remanent state, coercivity and remanent magnetization due to the static coupling action of neighboring elements, When the distance is twice as outer diameter, it’s affection could be ignored.α=60o更多还原