Micromagnetic simulation of an ultrasmall single-pole perpendicular write head

In single-pole heads with a pole tip cross section trimmed down to 100×200 nm by focused ion beam, the remanence of the head becomes nonzero if the pole length is too high. Large-scale three-dimensional micromagnetic simulations are performed to understand this effect, and to calculate the critical length of the pole as a function of the pole tip cross section.