Digital recording properties of evaporated cobalt films

Thin coatings of cobalt, cobalt-nickel, and cobalt-phosphorous have been in use for some years as a medium in recording drums. Recent papers [1]-[3] have described the recording properties of chemical- and electro-deposits on flexible plastic bases for in-contact digital tape recording. TheBHloop squareness and high coercivities achievable in films of a few microinches thickness makes them particularly suitable for high packing density storage. This paper describes the preparation and recording properties of vacuum-deposited cobalt films of varying thickness and coercivity. Comparisons made with oxide tapes show that a marked improvement in packing density is achievable. Correlations between pulse width and amplitude with thickness and magnetic properties throw some light on the mechanism of pulse recording.