Effects Of Underlayer Microstructure On Disk Media

It is well known that microstructural features of magnetic thin films such as grain size, grain shape, orientation and crystallinity, play an important role in the determination of their extrinsic magnetic properties. The extrinsic magnetic properties of the films, in turn, play an important role in determining the recording performance of the thin film media. In this presentation a review of some of the methods we have used to alter the microstructure of thin magnetic films (and hence their recording performance) will be presented. The focus will be on those methods used which change certain features of the microstructure of the underlayers so as to manipulate the recording performance of the subsequently deposited CO based alloy thin films used as recording media. In particular, an overview of our work on the development of new underlayer materials such as FeAl and NiAl will be presented. The crystallographic texture developed in these materials is the 211 texture. How this 211 underlayer texture affects the development of a unique texture in hcp Co based alloy thin films will be discussed. Methods of investigation include x-ray diffraction, tilted electron beam diffraction and electron microdiffraction. Methods used to increase the degree of crystallographic texture of the magnetic films will also be presented. These methods include the use of seed layers (films under the underlayer) such as MgO, which affect the degree and type of crystallographic texture of the underlayers, which in turn affect the texture of the magnetic films. Included in the presentation will be our findings on the role of thin Cr underlayers on the development of perpendicularly oriented CoCrPt films.