Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
2001-06-29
2004-06-01
Rickman, Holly (Department: 1773)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S690000, C428S900000, C428S336000, C428S667000, C428S668000
Reexamination Certificate
active
06743528
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a magnetic recording medium suitable as a recording medium for a hard disc device.
2. Discussion of Background
In recent years, magnetic recording media have been developed for high density recording, As one of methods for reducing media noises, JP-A63-146219 or IEEE TRANSACTIONS ON MAGNETICS, 26(5), 2700-2705(1990) discloses that a magnetic recording film is made to have a multilayer structure comprising a plurality of magnetic layers and an interlayer interposed between the adjacent magnetic layers to reduce the magnetic interaction between the adjacent magnetic layers. Further, as a means to obtain a high coercive force for high recording density, it has been reported to employ, as an underlayer, NiAl having B2 crystal structure (IEEE TRANSACTIONS ON MAGNETICS, 30 (6), 3951-3953 (1994), EP0704839A1).
In said LP-A-63-146219, in order to reduce noises, an Al
2
O
3
, SiO
2
or Cr film has been studied as the interlayer to be used for a magnetic recording medium having the above-mentioned magnetic recording film having a multilayer structure, but reduction of noises is still inadequate for an application in future wherein a GMR head will be used. In said EP0704839A1, NiAl has been studied as the underlayer, but no study has been made to let the magnetic recording film have a multilayer structure comprising a plurality of magnetic layers and an interlayer interposed between the adjacent magnetic layers to reduce the magnetic interaction.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a magnetic recording medium having a medium noise substantially reduced and being capable of high density recording.
The present invention has been made to accomplish the above object and provides a magnetic recording medium comprising a non-ferromagnetic substrate and a magnetic recording film formed on the substrate with an underlayer interposed therebetween, wherein the magnetic recording film comprises a plurality of magnetic layers and an interlayer made of a material having a B2 crystal structure or an interlayer made of Ru, disposed between the adjacent magnetic layers.
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Hiruma Takehiko
Imakawa Makoto
Suekane Michinobu
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