A NEW SERIES OF QUATERNARY CO-ALLOYS FOR HIGH-DENSITY RIGID-DISK APPLICATIONS

New quaternary media CoCrPtTa (Q) with Hc Op to 2400 Oe and Mrt greater than 1.3 memu/cm2 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 same remanence magnetization and slightly higher signal amplitudes. XRD and TEM data show larger grain-size and more grains with e-axis in-plane orientation in the Q media which can account for the higher coercivity.