Thin evaporated films with high coercive force

A technique allowing the preparation by vacuum evaporation of a material useable as a storage medium in digital magnetic recording is described. It consists of the evaporation of successive chromium and cobalt layers on a substrate, the nature of which seems indifferent. The coercive force can be adjusted from 200 to 600 Oe by adjusting the cobalt layer thickness. Superimposing identical double layers of chromium-cobalt allows one to obtain the required amount of flux. Such a multiple layered film gives properties identical to those of a homogeneous magnetic material with a coercive force between 200-600 Oe and an induction better than 10 000 gauss. These properties are isotropic. High squareness of the hysteresis cycle, with Mr/Ms > 0.95, is achieved.