Abstract
A reduction method of the medium noise which will be a serious problem for future ultra high density recording was studied. It was thought that a double layered perpendicular recording medium developed so far shows a rather large medium noise. It was found that a medium noise of a double layered medium could be reduced when the noise from a recording layer was reduced. To realize this, we proposed(1)to insert a very thin intermediate layer between a soft magnetic back layer and a recording layer and(2)to add a small amount of nitrogen during deposition of the back layer. Though the intermediate layer deteriorates the crystal growth of the recording layer, a fine grain size and a fine magnetic domain size of the recording layer could be realized on the soft magnetic back layer. Nitrogen addition to the back layer had an effect to grow it with multiple crystal orientations that led to realize a fine grain growth of the recording layer. Finally, the noise from the recording layer rather than that from the soft magnetic backlayer is dominant medium nooise for the double layered medium.
