Magnetic recording medium with improved recording density - uses thin film of cobalt containing oxygen with the main magnetic axis at 20 to 80 degrees with the horizontal deposited by evaporation

摘要

The magnetic medium features a magnetic layer composed mainly of Co and oxygen and has magnetic anisotropy with the main axis oriented at an angle of 20-80 degrees with the surface of the non-magnetic substrate, pref. 40 deg. or more. The coercive field-strength Hs at the surface of the magnetic layer is larger than the coercitive field strength Hb at the interface with the substrate, pref. 600-2000 Oe with Hb less than 600 Oe or especially 800-1500 Oe with Hb at 300-500 Oe. The film compsn. is pref. (FexCoyNiz)(100-m)Om in which x+y+z = 100, x is 0-10, z is 0-40 and m is 5-20. The wave-form reproduced by a recording is pref. characterised by a ratio r of the pulse-height below to the pulse-height above the base-line of 0-0.3 when a ring-head is used. The ring-head used pref. has a gap-width of 0.1-0.5 micron. The magnetic film can be deposited directly on the non-magnetic substrate or on a non-magnetic substrate. USE/ADVANTAGE - The film shows improved signal/noise ratio and allows an increased recording density compared with vertically and longitudinally magnetised films. The structure allows the film to be magnetically saturated during recording. the films are used for optical storage.