Head and media requirements for high density recording

The extension of magnetic recording to very high areal density requires that all the critical parameters of the system be reduced to extremely small values. The recording head parameters have to be scaled down, as well as the media magnetic parameters and the media thickness. Furthermore, pulse-slimming equalization techniques are effective in increasing the recording density by reducing intersymbol interface and eliminating negative sidelobes. The author discusses the limitations of conventional ferrite heads, and the advantages of thin-film inductive heads deposited by sputtering and/or electrodeposition onto a very hard ceramic wafer the structure of the head elements being defined by photolithography and dry and wet etch steps, and thin-film magnetoresistive read heads. The latter are particularly advantageous on inner tracks of small-diameter disk drives where linear velocity is relatively slow. Integrating a magnetoresistive read head with an inductive write head not only improves the readback sensitivity but also solves track interference problems during reading, since the width of the read element can be made narrower than the width of the write head. Critical requirements for longitudinal-recording media in general and thin-film disks in particular are also considered