Anneal-lessDomainWallDisplacementDetectionof15Gbit.PDFVIP

Anneal-less Domain Wall Displacement Detection of 15 Gbit/in2 land-groove recording using a deep groove substrate and a red laser Tetsuhiro Sakamoto*, Yasuhito Tanaka, Shingo Imanishi, Motohiro Furuki, Nobuyuki Arakawa and Kazuhiko Fujiie a Optical System Development Group, Broadband Network Company, Sony Corporation 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo, Japan 141-0001; aNetworked CE Laboratories, Sony Corporation Shinagawa Tec. 2-15-3 Konan, Minato-ku, Tokyo, Japan 108-6201, ABSTRACT Domain Wall Displacement Detection (DWDD) medium with no annealing method, which we call anneal-less DWDD medium, has been improved for practical use. The key technologies of our progress are not only an optimum design of the magnetic film structure but also a deep groove substrate for land-groove recording with a quite unique groove form. The substrate was prepared by using the mastering process with a reactive ion etching (RIE) method. We achieved 15 Gbit/in2-areal density with wide system tolerances using the anneal-less DWDD medium, a 660nm-laser and a 0.60 NA objective lens. The areal density corresponds to 4.7 GB-capacity on a disc like MiniDiscTM (MD) with a 64 mm- diameter. Keywords: domain wall displacement detection, DWDD, land-groove recording, deep groove, reactive ion etching, RIE, MiniDisc, red laser, DVD, 4.7GB 1. INTRODUCTION DWDD has the most potential to realize high linear density without using a blue laser or a lens of a high numerical aperture (NA). It offers the possibility to enhance the existing format of magneto-optical (MO) disc while keeping the conventional optical parameters unchanged. The authors previously reported the DWD