Ryuichi Yokoyama

Anneal-less domain wall displacement detection of 27 Gbit/in2 land/groove recording using a deep groove substrate and a blue laser

We have studied an anneal-less domain wall displacement detection (DWDD) disk of a land/groove recording on a deep groove substrate using a numerical aperture (NA) 0.65 objective lens and a blue laser diode (LD). The substrates were prepared using a stamper formed by reactive ion etching (RIE) and O2 plasma treatment to realize both steep side-wall angles and smooth surfaces on the substrates. In designing the groove shape, we have clarified three key factors: the groove edge shape, the groove depth and the land width. These factors affected the magnetic film discontinuity at the groove edge and the recording power margin on the land. We have achieved a recording density of 27 Gbit/in2 by optimizing the groove shape.