Effects of CoCrZr seed layer on noise properties and microstructure of CoCrPt media

We have developed a nonmagnetic (CoCr30)Zr-x [x=7, 10, 14 at. %] seed layer for CoCrPt glass media and have compared its structural and noise properti es to those of the media with a Ta/Zr dual seed layer, which have lower med ia noise than the media with a Cr seed layer. The media with a [CoCr30)Zr-1 0 seed layer had lower media noise than that with the Ta/Zr dual seed layer , which is attributed to reduced grain size in the magnetic layer. However, the media noise increased drastically owing to a 78% increase of the grain size in the magnetic layer when the Zr content in the seed layer increased from 10 to 14 at. %. The transmission electron microscope analysis indicat es that the (CoCr30)Zr-10 seed layer has a nanocrystalline structure, while CoCr30)Zr-14 was almost amorphous. This would be the main reason of the dr astic change in the grain size of the magnetic layer. The microstructure of the CoCrZr seed layer is very sensitive to the Zr content and strongly aff ects the microstructure of the magnetic layer and thereby media noise. (C) 1999 American Institute of Physics. [S0021-8979(99)52008-2].