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US 5,853,847 AGranted
Magnetic recording medium and its manufacture
OwnerMigaku Takahashiinventor
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OwnerMigaku Takahashiinventor
Estimating the term…
An inexpensive high-density recording medium which is increased in coercive force without using expensive ferromagnetic metallic layer. In a magnetic recording medium on the base body of which a ferromagnetic metallic layer is formed on a base body with a metallic underlying layer in between and which utilizes reversal of magnetization, the oxygen concentration in the ferromagnetic metallic layer is 100 wt. ppm or less, and in addition, oxygen concentration in the metallic base layer is also 100 wt. ppm or less. In a method of manufacturing a magnetic recording medium on the base body of which the metallic base layer and ferromagnetic metallic layer are successively formed by sputtering, the impurity concentration of Ar gas used for the formation of the layer is 10 ppb or less. Before forming the metallic base layer, in addition, the surface of the base body is cleaned by high-frequency sputtering using Ar gas the impurity concentration of which is 10 ppb and surface section of the base body is partially removed to a depth of 0.2-1 nm.
A magnetic recording medium wherein a ferromagnetic metallic layer is formed on a surface of a base body with a metallic base layer in between, which employs reversal of magnetization, characterized in that an oxygen concentration within crystal grains of said ferromagnetic layer is 100 wtppm or less.
A magnetic recording medium wherein a ferromagnetic metallic layer is formed on a surface of a base body with a metallic base layer in between, which employs reversal of magnetization, characterized in that an oxygen concentration within crystal grains of said metallic base layer is 100 wtppm or less.
A magnetic recording medium, wherein a ferromagnetic metallic layer is formed on a surface of a base body, which employs reversal of magnetization, characterized in that an oxygen concentration within crystal grains of said ferromagnetic metallic layer is 100 wtppm or less.
A manufacturing method for magnetic recording media, wherein a metallic base layer and a ferromagnetic metallic layer are successively formed on a surface of a base body by a sputtering method, characterized in that Ar gas used in film formation has an impurity concentration of 10 ppb or less.
A manufacturing method for magnetic recording media, wherein a ferromagnetic metallic layer is formed on a surface of a base body by a sputtering method, characterized in that Ar gas used in film formation has an impurity concentration of 10 ppb or less.
Dependencies are inferred from the claim text.