A new series of quaternary Co-alloys for high density rigid-disk applications

Quaternary media CoCrPtTa(Q) with Hc up to 2400 Oe and Mrt greater than 1.3 memu/cm/sup 2/ have been investigated for longitudinal magnetic recording. Magnetic properties and microstructure of the films were compared with CoCrTa(T) media. The coercivity decreases monotonically with temperature, and the magnetization has a very small dependence on temperature. The differential remanence measurements of Q and T media indicate fairly strong interactions among the crystallites. The Q media with 5-10% Pt exhibit 25-75% higher coercivity than the ternary media T with same atomic percentage of Cr and Ta. The media Q, containing 9.5% less Co produce the same remanence magnetization and slightly higher signal amplitudes. X-ray diffraction and transmission electron microscopy (TEM) data show larger grain-size and more grains with c-axis in-plane orientation in the Q media which can account for the higher coercivity.<
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