Transition Shift and Overwrite Characteristics in Perpendicular Magnetic Recording

Shifts in perpendicular recording transition positions depending on the polarity of the prerecorded magnetization of a medium were investigated. Transitions are shifted toward the trailing direction when the polarity of the head field is opposite that of the leading-side magnetization. Conversely, they are shifted in the leading direction when the head field is of the same polarity as the leading-side magnetization. In this paper, we confirmed that these phenomena affect the overwrite performance. We measured the transition shifts in overwrite recording and studied the relation between transition shifts and overwrite. It is demonstrated that a bi-layer SPT head suppresses transition shifts, thus improving the overwrite characteristic.