Micromagnetic Simulation of head-field and write bubble dynamics in perpendicular recording

We have developed a finite-element micromagnetics model to investigate the magnetization and field dynamics of perpendicular recording heads. We have used a finite-difference micromagnetic recording model to study the influence of the head-field rise time and media velocity on the recording process. An analytical expression for the write bubble expansion velocity has been derived based on a linearized model, and we have compared it with dynamic micromagnetic simulations. It has been found to be directly proportional to the rate of change of field with time and inversely proportional to the head-field gradient. The write bubble expansion velocity needs to match or exceed the media velocity to minimize transition curvature.