PREPARATION OF PERPENDICULAR MAGNETIC RECORDING MEDIA BY ELECTROLESS PLATING METHOD

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The formation and evaluation on high function thin films by an electroless plating method were studied on the basis of the application of them to high density magnetic recording media of perpendicular magnetic recording system. The perpendicular anisotropy thin film is realized by the cobalt alloy plating films of CoNiReP and CoNiReMnP alloys. Moreover, the ternary CoNiP alloy suitable for perpendicular recording was finally developed by a new electroless plating bath. The cobalt alloy recording media with the underlayer of crystallized and amorphous NiP underlayers show the effects of so-called double layer (enhancement of output voltage) and of enhancing crystallinity of cobalt alloy which was able to record the higher density, respectively. When using NiWP plating underlayer, the both effects are produced and the very high recording density such as 300kFRPI output signal of the third peak is established by the cobalt alloy media with NiWP underlayer. The most suitable thickness of the underlayer is confirmed to be so thin layer of 300 A. Moreover when using NiMoP underlayer, the cobalt alloy medium is automatically formed with an initial soft layer and the thickness of the initial soft layer is controlled by the Mo concentration of NiMoP underlayer.With some analytical techniques of SEM, TEM, RHEED and very local area EDX, and also with a combination of wet etching method with them, the structure of the plated media is suggested to be the segregated deposition conditions that the magnetic parts of Co rich area are scattered in the non-magnetic area of an amorphous NiP structure. Such an segregated condition can enhance an isolation of magnetic domains and it makes it possible to record the higher magnetic recording density.Finally, we proposed a guiding principle of perpendicular magnetic recording media with a combination of ring-type head.