Magneto-optical recording materials system
AssigneeJohnson Matthey Public Limited Company
InventorsJoseph Miller, Derek P. A. Pearson, Philip G. Pitcher
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Abstract
A materials system in which exchange coupling is achievable has the potential for allowing direct overwriting of data and comprises at least two multilayer films of platinum and cobalt with independently controlled coercivity and Curie temperatures.
Claims29
A magneto-optical recording medium comprising, a composite multilayer laminate system wherein multilayer films of platinum and cobalt are exchange coupled and have perpendicular magnetic anisotropy, such system having the potential to allow direct overwriting of data, said system comprising a substrate material and at least two multilayer films comprising a platinum layer and a cobalt layer, and wherein there is provided at a multilayer interface a spacer comprising one platinum layer of one or both multilayers or a separately-deposited material, one of said multilayer films having a room temperature coercivity (H.sub.c) of 2 to 15 kOe and a low Curie temperature (T.sub.c) of 100.degree. C. to 400.degree. C. and known as the memory layer and one of said multilayer films having a low room temperature coercivity of 0.5 to 10 kOe and a high Curie temperature of 175.degree. C. to 500.degree. C. and known as the reference layer, the difference in coercivity and Curie temperature between the two multilayer films being sufficient to permit a direct overwriting process.
Dependencies are inferred from the claim text.