Magnetization Dynamic Analysis of Square Model CoFe and CoFeB Ferromagnetic Materials Using Micromagnetic Simulation

In this study, dynamic magnetization of square model CoFe and CoFeB ferromagnetic materials were observed using micromagnetic simulation based on LLG equation. The geometrical side size was varied from 50 to 500 nm with the thickness of 5 nm and 10 nm. For simulation process, the used damping factor was 0.05 and the cell size of 2.5×2.5×2.5 nm³ was used with respect to exchange length of CoFe and CoFeB. The external magnetic fields were applied in in-plane and out-plane direction to generate magnetic hysteresis loop. It is found that the coercivity decreased as square size increased for both in-plane and out-plane magnetization direction. The coercivity were around 40 to 200 mT for in-plane field magnetization of CoFe. The coercivity tends to constant at 40 mT in diameter less than 100 nm and zero coercivity for diameter greater than 100 nm for out-plane field magnetization. Compared to CoFe, the coercivity in out-plane field is higher than in-plane field in CoFeB square. It is also observed that the switching time and nucleation field increased as the size increased in out-plane direction of both CoFe and CoFeB. The results showed that the different characteristics of magnetic anisotropy of both materials are important in the development of high density magnetic storage.