Design and crystallography of multilayered media

In this paper several different schemes for multilayered longitudinal magnetic recording media are presented and discussed. We will focus the discussion on those schemes on which we have worked over the past several years, emphasizing the role of new underlayers, seed layers, intermediate layers and interlayers. In each case we discuss the role that each of the layers plays in determining the important magnetic properties and recording performance of the Co based hcp thin film media. Included in the paper is a review of the role of new underlayers (NiAl and MgO), seed layers (MgO), intermediate layers (Cr, Co alloys) and interlayers (Cr, Al, Cu and Ag). Throughout we discuss the role of epitaxy between the various layers and demonstrate that the resulting microstructure and crystallographic texture of the films depends strongly on such epitaxy. These characteristics, in turn, control the resulting magnetic properties of the Co based films such as in plane coercivity H-c and squareness ratio, S*.