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A new coercivity-structure was proposed, and a new process technique was developed for controlling the Hc of second and subsequent magnetic-layers in multi-layer media. A narrow slit cathode was used to sputter Cr-interlayer. Conventional and new Hc-gradient CoCrTa-bi-layer media were sputtered by varying Cr-interlayer thickness 0-25[Angstrom] with fixed Cr-underlayer and magnetic layers. In one case, to achieve higher Hc for the top-magnetic layer, Hc gradient bilayer media of Mrt:3.6 memu/[cm.sup.2] were sputtered by using -250V DC-bias during second magnetic-layer deposition which produced about 300Oe higher Hc for the top-layer. The bi-layer media reduced media-noise about 30% and increased SNR about 5dB in comparison to mono-layer media at 66.3 KFCI recording-density. However, conventional bi-layer media produced about 6-7 dB lower overwrite(OW) in comparison to mono-layer media, whereas the new Hc-gradient bi-layer media with higher Hc showed about 5 dB higher OW and 5-12% higher HF-amplitude in comparison to conventional bi-layer media.

A process has been developed which uses very thin Cr-underlayer for CoCrTa-media for high-density recording. The media sputtered using this technique revealed that by decreasing Cr-underlayer thickness from 2000 [Angstrom] to 200 [Angstrom], orientation-ratio increased from 1.27 to 1.6, squareness-ratio increased from 0.81 to 0.86, and Mrt increased from 3.25 to 3.97 memu/[cm.sup.2]. The Mr value is increased because of the higher squareness. The higher Mr gives a higher Mrt product which produced higher signal output by about 10%. Also, the noise performance was comparable for the media with thin and thick Cr-underlayers. X-ray diffraction patterns showed strong in-plane preferred orientations, Cr(200) and Co(1120) textures as a function of Cr-underlayer thickness.

A new sputtering technique for mixing two or more magnetic alloys has been developed. This new technique produces magnetic compositional-gradient along film thickness. In the present study, CoNiCr and CoCrTa - magnetic alloys were used for this new sputtering scheme. In one case, the low-noise characteristics of the first magnetic layer - CoCrTa with Ms:659 emu/cc is combined with the high Br, remanence magnetization characteristics of the second magnetic layer - CoNiCr with Ms: 1110 emu/cc. The performance of CoNiCr/CoCrTa-gradient media was better than the CoCrTa/CoNiCr-gradient media. Magnetic and recording properties of the gradient thin-film media were compared with the single-layer media of CoNiCr and CoCrTa. The coercivity of gradient media was about 20% higher than their single-layer media. The remanence magnetization of gradient-media is about 25-30% higher than the CoCrTa-single layer media. Also, it was observed that the CoNiCr/CoCrTa-compositional gradient media produce about 40% lower media-noise in comparison to CoNiCr-single layer media.

Microstructural studies using transmission electron microscopy have been performed on Sendust films deposited on both polycrystalline and single crystal ferrites. We observed a strain-induced contrast in both the ferrite and Sendust and a large number of dislocations in the ferrite region near the interface. However, no intermediate layer of Al2O3 or SiO2 was formed by interdiffusion at the interface. We found that both the in-plane crystallographic texture and the microstructure of the Sendust films depend on the orientation of the underlying single crystal ferrite substrates, even though the out-of-plane crystallographic texture appears to be independent of ferrite crystal orientation. A model has been proposed to explain the microstructural origin of the magnetically degraded layer formed at the interface of the Sendust film and ferrite cores in the Metal-in-Gap heads.