Magnetic properties and read-write characteristics of multilayer films on a glass substrate

Magnetic properties in read-write characteristics of a magnetic medium deposited on a soda-lime silicate glass substrate by DC magnetron sputtering at 10 mTorr partial pressure were studied. Two CoNiCr alloy films (each 35 nm in thickness) separated by a chromium film (12.5 nm in thickness) were sputtered onto a chromium underlayer, and a carbon film was deposited on the top of the cobalt alloy film for surface protection. The coercivity and remanence-thickness product were controlled independently. Higher coercivity was obtained as the film thickness of the chromium underlayer increased; 1000 Oe and 1400 Oe of coercivity were attained at 75 nm and 350 nm of underlayer thickness, respectively, while the remanence-thickness product stayed constant at 0.05 G-cm. Read-write characteristics of this five-layer system (double magnetic layers) deposited on a 5-1/4-in glass substrate with 950 Oe of a coercivity showed little difference in its parametric values compared with a three-layer system (single magnetic layer)