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Micromagnetic simulation of Sm–Co/α-Fe/Sm–Co trilayers with various angles between easy axes and the film plane 下载免费PDF全文
Hysteresis loops and energy products have been calculated systematically by a three-dimensional(3D) software OOMMF for Sm–Co/α-Fe/Sm–Co trilayers with various thicknesses and β, where β is the angle between the easy axis and the field applied perpendicular to the film plane. It is found that trilayers with a perpendicular anisotropy possess considerably larger coercivities and smaller remanences and energy products compared with those with an in-plane anisotropy.Increase of β leads to a fast decrease of the maximum energy product as well as the drop of both remanence and coercivity. Such a drop is much faster than that in the single-phased hard material, which can explain the significant discrepancy between the experiment and the theoretical energy products. Some modeling techniques have been utilized with spin check procedures performed, which yield results in good agreement with the one-dimensional(1D) analytical and experimental data, justifying our calculations. Further, the calculated nucleation fields according to the 3D calculations are larger than those based on the 1D model, whereas the corresponding coercivity is smaller, leading to more square hysteresis loops and better agreement between experimental data and the theory. 相似文献
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一、引言在物质结构教学中,系统消光这一部分内容是教学中的一个难点。产生系统消光的原因是这样:在讨论晶体对x光的衍射条件时,是以具有素单位的空间点阵为模型来研究的,从而得到描述衍射条件的Lane方程 a.(S—S_0)=hλ b.(S—S_0)=kλ(h、k、l为整数)(1) c.(S—S_0)=1λ数组h k l被定义为该方向上衍射线的衍射指标。但实际晶体对应的空间点阵单位可以 相似文献
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文章以斜齿轮为研究对象,综合考虑混合润滑状态下摩擦动力学特性对齿面应力分布的影响以及渗碳表层硬度梯度和残余应力的非均匀分布特征,以风险疲劳累积理论为基础建立了疲劳裂纹萌生寿命预估模型;考虑裂纹在晶粒内部的非线性扩展规律以及晶界处的非连续扩展特征,建立了短裂纹扩展模型;针对长裂纹扩展过程中不同阶段扩展速率的差异,建立了长裂纹扩展速率统一方程,从而完成了对齿轮接触区疲劳裂纹萌生及扩展过程全寿命的预估.计算结果表明:齿面应力分布受动载荷和润滑状态的影响显著;在残余应力作用下,有效剪切应力在渗碳表层出现多个波峰,疲劳裂纹萌生位置多点化,导致裂纹尺度有所不同,疲劳寿命存在差异,失效形式多样化. 相似文献
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运用三维数值模拟计算方法,计算了膜面外不同易轴取向下Nd2Fe14B/Fe65Co35磁性双层膜的磁滞回线、角度分布、成核场、矫顽力和磁能积等,并与实验结果进行了细致比较.计算结果表明:只有当易轴与外场之间的夹角β=0?时,才有明显的成核现象,其成核场和矫顽力均随着软磁相厚度Ls的增加而降低;随着易轴偏角β的增大,剩磁逐渐减小,磁滞回线的方形度降低,从而磁能积减小,在Ls=1 nm,β=0?时磁能积(561.61 kJ/m3)最大.理论计算所得的磁滞回线与实验磁滞回线符合得很好,剩磁和矫顽力的理论值与实验值相差很小. 相似文献
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The hysteresis loops as well as the spin distributions of Sm–Co/α-Fe bilayers have been investigated by both threedimensional(3D) and one-dimensional(1D) micromagnetic calculations, focusing on the effect of the interface exchange coupling under various soft layer thicknesses t~s. The exchange coupling coefficient Ahsbetween the hard and soft layers varies from 1.8 × 10~(-6)erg/cm to 0.45 × 10~(-6)erg/cm, while the soft layer thickness increases from 2 nm to 10 nm. As the exchange coupling decreases, the squareness of the loop gradually deteriorates, both pinning and coercive fields rise up monotonically, and the nucleation field goes down. On the other hand, an increment of the soft layer thickness leads to a significant drop of the nucleation field, the deterioration of the hysteresis loop squareness, and an increase of the remanence. The simulated loops based on the 3D and 1D methods are consistent with each other and in good agreement with the measured loops for Sm–Co/α-Fe multilayers. 相似文献
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运用微磁学方法结合物质参数探究了垂直取向Nd2Fe14B/α-Fe磁性三层膜的磁化反转过程,计算出成核场、钉扎场以及磁滞回线随Ls(软磁相厚度)的变化,并与相关的实验和理论数据进行比较.由于考虑了退磁能量项,垂直取向的成核场比平行取向时低,在外磁场还没有反向时就发生了成核.随着软磁相厚度的增加,理论矫顽力从等于成核场(同时也等于钉扎场),到等于钉扎场,再到小于钉扎场,矫顽力机理由成核变为钉扎.
关键词:
成核场
钉扎场
矫顽力
磁滞回线 相似文献