磁性纳米片微波磁性的微磁学研究

发布时间：2018-09-04 13:10

【摘要】：20世纪70年代以来,磁性纳米材料经历了从产生到发展再到壮大的过程,渐渐成为一种新型磁性材料。磁性纳米颗粒的特殊效应(量子尺寸效应、小尺寸效应、表面效应和宏观量子隧道效应等)将会引起其磁特性发生强烈的变化,表现出独有的磁特性,受到了人们的广泛关注。磁性颗粒的磁性质可以采用组分控制、制备工艺调节、热处理等多种方法来进行调控。本文我们侧重探讨缺陷和颗粒之间的磁相互作用对磁性颗粒静态和动态磁性质的影响特征。主要工作如下:(1)通过微磁学模拟,探讨了不同位置、不同大小的孔洞形和坑形缺陷对矩形铁磁性纳米片的静态磁矩分布和磁谱的影响。结果表明,孔洞形或坑形缺陷对矩形铁磁性纳米片的磁性能的影响依赖于缺陷位置的变化以及缺陷的尺寸和形状的变化。一般这些缺陷可能导致磁谱的主共振峰移动到较低的频率位置上。这些结果为通过图案化方法来控制和设计矩形铁磁性纳米片的静态和动态特性提供了参考。(2)用微磁学模拟方法研究了相对位置、颗粒间距和磁各向异性方向对两矩形铁磁性纳米片磁性能的影响特征。结果表明,相对位置、颗粒间距影响两矩形铁磁性纳米片共振峰频率的分布,当两矩形纳米片磁各向异性方向所呈角度由0°增加到30°时,其磁性质没有明显的变化,而从30°到90°时,其磁性质对磁各向异性方向变化比较敏感。此外,结果还表明改变两个矩形铁磁性纳米片的磁各向异性方向可显著影响共振峰的数目、强度、峰宽和频率分布。因此,我们可以通过改变纳米片相对位置、颗粒间距以及磁各向异性方向来调控铁磁性纳米片的磁性质。可用于制备具有各种频率和较宽吸收频带的微波吸收材料。
[Abstract]:Since the 1970s, magnetic nanomaterials have undergone a process from generation to development and then to growth, and have gradually become a new type of magnetic materials. The special effects of magnetic nanoparticles (quantum size effect, small size effect, surface effect and macroscopic quantum tunneling effect) will cause strong changes in their magnetic properties, showing unique magnetic properties, which have attracted widespread attention. The magnetic properties of magnetic particles can be controlled by component control, preparation process adjustment, heat treatment and so on. In this paper, we focus on the influence of the magnetic interaction between defects and particles on the static and dynamic magnetic properties of magnetic particles. The main work is as follows: (1) the effects of different positions and sizes of holes and pit-shaped defects on the static magnetic moment distribution and magnetic spectrum of rectangular ferromagnetic nanocrystals are investigated by micromagnetic simulation. The results show that the effect of hole or pit defects on the magnetic properties of rectangular ferromagnetic nanocrystals depends on the change of defect location and the size and shape of defects. In general, these defects may cause the main resonance peak of the magnetic spectrum to move to a lower frequency position. These results provide a reference for controlling and designing the static and dynamic characteristics of rectangular ferromagnetic nanocrystals by patterning method. (2) the relative position is studied by micromagnetic simulation. The effect of particle spacing and magnetic anisotropy on the magnetic properties of two rectangular ferromagnetic nanocrystals. The results show that relative position and particle spacing influence the frequency distribution of the resonance peak of the two rectangular ferromagnetic nanocrystals. When the angle of the anisotropic direction of the two rectangular ferromagnetic nanocrystals increases from 0 掳to 30 掳, the magnetic properties of the two rectangular ferromagnetic nanocrystals have no obvious change. From 30 掳to 90 掳, the magnetic properties are sensitive to the direction of magnetic anisotropy. The results also show that the number, intensity, width and frequency distribution of the resonance peaks can be significantly affected by changing the magnetic anisotropy direction of the two rectangular ferromagnetic nanocrystals. Therefore, we can adjust the magnetic properties of ferromagnetic nanocrystals by changing the relative position, the distance between particles and the direction of magnetic anisotropy. It can be used to prepare microwave absorbing materials with various frequencies and wider absorption bands.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1;O482.5

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