Write field analysis and write pole design in perpendicular recording

We have developed a three-dimensional micromagnetic perpendicular recording model to analyze high-density perpendicular write fields. Here, we compare a tapered-neck pole,with a very small throat height to various write pole designs or a single-pole head. In studying the effects of throat height and write pole-return pole spacing, we found that, for a large throat height, both the write field and field gradient decrease as the throat height increases. The write field shape changes significantly at the leading edge for a write pole-return pole spacing less than 300 nm. The effects of soft-underlayer (SUL) permeability, saturation, and thickness basically follow the analytical formula. The net recording field is almost constant for SUL permeability above about 50.