Hisao Arimune

Environmental Stability of the Magneto-Optic Medium

H. Arimune, T. Maeda, and T. Yamada are with Central Research Lab., Kyocera Co. Ltd., Kagoshima. From Digests of the Eighth Annual Conference on Magnetics in Japan 1984, page 128. The copyright for the original Japanese article is held by the Magnetic Society of Japan. The copyright for the English version of this article as it appears here is held by the Institute of Electrical and Electronics Engineers, Inc. layer. From the figure we can verify that, in single-layer films, Tb selective oxidation takes place from the changes in Hc (t)/Hc (o) and GKr(t)/OKr(O). The primary cause of the Kerr enhancement is due to the TbFe oxidation layers which have become transparent or inplane magnetic film because of surface oxidation. We studied TbFe, TbFeGdCo and DyFeGdCo single-layer magnetic film and learned that adding Co to multi-element films, or substituting Tb for Dy or Gd improved corrosive resistance. Fig. 2 shows the results of using SiO and SiO2 as protective films and, for the sake of comparison, using Si3N4 in a sandwich structure medium. From this we discovered that 1) even an oxide film would make an anti-oxidizing film if it were a deoxidization substance, 2) oxidation occurs when the free oxygen in SiO2 which is in contact with the magnetic layer is drawn in from the boundary, 3) the deterioration due to mixing oxygen that occured while preparing the film was negligible, and 4) initial surface oxidation took place during SiO2 film making. The AES results in Fig. 3 are given for reference. We studied SiC, CdS and MgF2 in the same way and found some pin holes developed during the initial period, and the magnetic

Thermal Stability and Reliability of Magneto-Optical Media with Periodic Structures

Using a constant power source and both binary and single target magnetron sputtering, samples with periodic structures were produced while varying the substrate rotation speed. Characteristics reached a maximum at 5 rpm and in-plane magnetization films resulted at 1 rpm. Annealing samples with a protective layer causes all characteristics except the Kerr rotation angle (θK) to vary. These variations were peculiar to periodic structures. The change in the coercive force (Hc) indicated a structural transition. The large Hc and saturation magnetization (Ms) values promise superior recording resolution. The carrier-to-noise ratio was improved by one to two dB and showed no changes after 1000 h in the open air at 55°C.