Alternating-DC track servo pattern for perpendicular recording

A perpendicular recording system can provide improved writing ability on high-coercivity media and stabilize high-density bits against the superparamagnetic effect. On the other hand, when bits are written on a perpendicular medium at low density, as is the case with the PES (position error signal) region of a conventional servo pattern, linearity in reading/writing operations is distorted, which are strongly affected by the regions of dc magnetization. This paper presents a way in reducing such distortion of characteristics of reading/writing processes using perpendicular media.