Dynamics in perpendicular recording using 3D micromagnetic simulation

Abstract

Summary form only given A 3D micromagnetic perpendicular recording model has been developed to study the dynamics of perpendicular recording. A single pole with tapered neck (K. Gao and H.N. Bertram, GBO8 MMM 2001), the shield pole, the medium and the soft underlayer (SUL) are included in the model. The basic geometry corresponding to 200 Gbit/in/sup 2/ is used. A linear ramp input flux is applied uniformly along the pole surface opposite to the ABS. The initial magnetization in the medium is in the perpendicular direction. Recording data rates of 1 GHz and 2 GHz are used with flux rise times of 0.2 ns and 0.1 ns, respectively. The write field at a magnetic spacing of 20 nm, corresponding to the center of the medium, is evaluated to study the field rise time, shape and magnitude. Various damping constant values of 0.02, 0.2 and 1 have been used in the simulation to investigate field rise time and magnetization reversal speed. At recording speed of 1 GHz, our simulation shows that after 1 ns, the dynamic write field shape and magnitude are about the same as compared with the static write field. The magnetostatic field of the medium causes a maximum of 10% write field magnitude decrease in a hard transition. After removing the applied flux, the remnant field from the write pole is on average 10% of the saturation field. The perpendicular component of the remnant magnetization in the ABS surface is also about 10%, depending on the medium magnetization state. For a flux rise time of 0.2 ns, the head fields follow the reversal flux closely. However, for a small damping constant /spl alpha/=0.02, the perpendicular component of magnetization in the ABS requires about 0.5 ns to reach saturation. For a flux rise time of 0.1 ns, both the head field rise time and average magnetization from the ABS increase with decreasing damping constant. Results show that for a flux rise time of 0.1 ns, the head fields follow the applied flux reversal until they pass /spl sim/50% of saturation value. After that, the head field cannot follow the external flux and a relatively long approach saturation is observed.