Servo-Pattern and Guard-Band Formation in Perpendicular Discrete-Track Media by Ion Irradiation

An embedded servo pattern was fabricated using the ion irradiation method. The servo pattern was analyzed using a spinstand with a flyable read/write head and compared with a conventional medium written by a dedicated servo writer. The embedded servo patterns were clearly detected. The good quality of the servo signal proved the effectiveness of the ion irradiation process. No domain wall noise was observed in the ion-irradiated servo area, indicating the absence of large maze domains. LLG simulations were used to investigate the behavior of written tracks and soft-guard-bands of DTM fabricated by ion irradiation. A conventional continuous medium showed an expansion in the width of written tracks as the continuous layer thickness increased. In DTM, track expansion was prevented by the grooves. According to the simulation results, similar magnetic track widths can be obtained in media with soft-guard-bands as in conventional DTM media with air grooves. The K_u reduction in the grooves should align the magnetization of the irradiated guard band region in-plane to realize a successfully erased guard band.