Study On The Magnetic Process Of Perpendicular Media Founded On Micromagnetic Finite Element Method

The demagnetic field of perpendicular media decreases as the recording density increased. Also, the thermal instability which is caused by the shrink of the grain size can be conquered by increasing the thickness of the perpendicular film. These characteristics make the perpendicular media become a prominent candidate of the high density storage media. Although the perpendicular recording product has shown his appearance in the market, its recoding density is much lower than the value predicted in theory. The fabrication of the perpendicular recording media becomes the key step which will make the recording density closer to the theoretic value. The micromagnetic finite element simulation provides a new approach to optimize microstructure of perpendicular media.The simulation can provide the details of the magnetization. Moreover, the grain size of the media can be changed in order to study the effect of the perpendicular media's microstructure on the magnetization. Therefore, the simulation can tell us how to fabricate the film we need. The micromagnetic finite element method is still in its development. The simulation of the magnetization of the perpendicular media could be split into three parts. The first part is to construct the model which can describe the characteristics of the granular perpendicular media. The Voronoi is an effective model. But after considering its compatibility with the finite element software, the ideal model of Voronoi hexagonal prism is chosen as the geometry model. Two different models of the media are constructed. One is the continuum model; the other is the segregate model. The tetrahedron is used to generate the finite element mesh. The second part is to investigate the micromagnetic theory to dig the techniques which can be used to calculate the magnetization in perpendicular media. There are two approaches can be employed. One is the Laudau energy minimization, the other is integration of LLG equation with respect to time. To get the solution of them, the finite element numerical method is used. The final part is the implement of Magpar which is the parallel micromagnetic finite element simulation. The two model constructed in the second part are simulated. The result of simulation proves that the smaller is the ratio of the diameter to the thickness of the grainδthe smaller the nucleation field Hn and the smaller grains have the tendency to form the larger reverse clusters. The calculated hysteresis loops can prove that the segregate model has higher coercive force Hc and remanent magnetization Mr.