Abstract
We have investigated the effects of stray magnetic field upon a perpendicular magnetic recording system, which consists of a single pole type head and a double-layered perpendicular medium. We found that fields in the plane of the disk could cause serious erasure. In addition, the writing operation significantly enhances this erasure. We checked SER degradation after applying an in-plane field with changing the head skew angle. We devised a new return pole design which was called 'corner step' structure, and confirmed that the alternative structure improves the robustness against external field.
