核((Nd0.7,Ce0.3)2Fe14B)-壳(Nd2Fe14B)型磁体反磁化的微磁学模拟  

Micromagnetic simulations of reversal magnetization in core((Nd0.7,Ce0.3)2Fe14B)-shell(Nd2Fe14B)type

作　　者：李栋 董生智[1] 李磊 徐吉元 陈红升[1] 李卫[1] Li Dong;Dong Sheng-Zhi;Li Lei;Xu Ji-Yuan;Chen Hong-Sheng;Li Wei(Division of Functional Materials Research,Central Iron and Steel Research Institute,Beijing 100081,China)

机构地区：[1]钢铁研究总院,功能材料研究所,北京100081

出　　处：《物理学报》2020年第14期211-221,共11页Acta Physica Sinica

基　　金：国家自然科学基金重大项目(批准号:51590882);国家自然科学基金(批准号:51871063)资助的课题.

摘　　要：以核((Nd0.7,Ce0.3)2Fe14B)-壳(Nd2Fe14B)型晶粒为研究对象,利用C++语言进行编程建模,通过微磁学模拟软件OOMMF进行计算仿真,系统讨论了核的尺寸、壳层厚度以及壳层分布对单晶粒磁体反磁化过程的影响.对于核((Nd0.7,Ce0.3)2Fe14B)-壳(Nd2Fe14B)型晶粒,当壳层厚度不变时,矫顽力随核的尺寸增加而单调递减.当核的尺寸不变时,壳层厚度的增加使得矫顽力先增加后降低.当核的尺寸不变,壳层总体积也不变时,壳层的不同分布会影响矫顽力的大小,其中当壳层仅平均分布于核的z面(垂直于z轴的两个面)时,矫顽力达到最大值.The effects of core size,shell thickness and shell distribution on the coercivity of single-grain core((Nd0.7,Ce0.3)2Fe14B)-shell(Nd2Fe14B)magnets are studied by programming and modeling them through using the C++language.All the micromagnetic simulations are carried out via object oriented micro magnetic framework(OOMMF).The results show that the coercivity decreases with the increase of core size when the shell thickness is constant.It is considered that for the grain,the increase in the size of the core leads the average magnetocrystalline anisotropy field to increase and the total demagnetization energy to increase,thereby contributing to the magnetization reversal occurring under a smaller external field.When the core size is unchanged,as the shell thickness increases gradually,the coercivity first increases and then decreases.The analysis of the position of the nucleation point shows that the reason why the coercivity increases in the early period is mainly that the nucleation point is located at the core-shell junction and belongs to the core.As the thickness of the shell increases,the exchange interaction effect between the magnetic moment of the shell and the one of the nucleation point is strengthened,so a larger external field is needed in the nucleation process.As for the decrease of the coercivity in the later period,the main reason is that the nucleation points are exactly the vertices of the shell(also the vertices of the grain),and the increase of the shell thickness conduces to increasing the total demagnetization energy,so the nucleation points can be formed under a smaller external magnetic field.With core size and shell volume kept unchanged,when the shell is distributed on the two easyaxis planes(i.e.the planes perpendicular to the easy axis)of the core,the coercivity of the magnet reaches a largest value.It is because that the nucleation points are located at the vertices of the shell(also the vertices of the grain),of which the magnetocrystalline anisotropy field is larger,and the demagneti

关 键 词：微磁学模拟 含铈磁体 核-壳结构 矫顽力 

分 类 号：O469[理学—凝聚态物理]