Magnetic recording medium
First Claim
1. A thin film magnetic recording medium, having:
- at least 2 magnetic layers formed on a non-magnetic substrate; and
a non-magnetic intermediate layer that is interposed between said magnetic layers and causes magnetizations of said magnetic layers to be anti-parallel to one another;
wherein a ratio HkB/HkA of an anisotropic magnetic field strength HkB of a magnetic layer on a side near to said substrate to an an isotropic magnetic field strength HkA of a magnetic layer on a side far from said substrate is 0.7 or less.
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Accused Products
Abstract
An object is to provide a magnetic recording medium giving high resolution, low noise and little thermal fluctuation and thus suitable for high density magnetic recording, and a high-capacity magnetic recording device realized by using this medium. A thin film type magnetic recording medium is used, having at least 2 magnetic layers formed on a non-magnetic substrate and a non-magnetic intermediate layer that is interposed between the magnetic layers and causes the magnetizations of the magnetic layers to be anti-parallel to one another, and wherein the ratio HkB/HkA of the anisotropic magnetic field strength HkB of the magnetic layer on the side near to the substrate to the anisotropic magnetic field strength HkA of the magnetic layer on the side far from the substrate is 0.7 or less, more preferably at least 0.4 and not more than 0.65.
60 Citations
17 Claims
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1. A thin film magnetic recording medium, having:
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at least 2 magnetic layers formed on a non-magnetic substrate; and
a non-magnetic intermediate layer that is interposed between said magnetic layers and causes magnetizations of said magnetic layers to be anti-parallel to one another;
wherein a ratio HkB/HkA of an anisotropic magnetic field strength HkB of a magnetic layer on a side near to said substrate to an an isotropic magnetic field strength HkA of a magnetic layer on a side far from said substrate is 0.7 or less. - View Dependent Claims (2, 12, 13, 14, 15, 16)
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3. A thin film magnetic recording medium, having:
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at least 2 magnetic layers formed on a non-magnetic substrate; and
a non-magnetic intermediate layer that is interposed between said magnetic layers and causes magnetizations of said magnetic layers to be anti-parallel to one another;
wherein a ratio HkB/HkA of an anisotropic magnetic field strength HkB of a magnetic layer on a side near to said substrate to an anisotropic magnetic field strength HkA of a magnetic layer on a side far from said substrate is 0.7 or less, and wherein a ratio HcoB/HcoA of a coercivity HcoB of the magnetic layer B on the side near to said substrate at 0K as obtained by extrapolating values of coercivity at 200K and 100K to a coercivity HcoA of the magnetic layer A on the side far from said substrate at 0K as obtained by extrapolating values of coercivity at 200K and 100K is 0.7 or less. - View Dependent Claims (4)
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5. A thin film magnetic recording medium, having:
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at least 2 magnetic layers formed on a non-magnetic substrate; and
a non-magnetic intermediate layer that is interposed between said magnetic layers and causes magnetizations of said magnetic layers to be anti-parallel to one another;
wherein a ratio HkB/HkA of an anisotropic magnetic field strength HkB of a magnetic layer on a side near to said substrate to an anisotropic magnetic field strength HkA of a magnetic layer on a side far from said substrate is 0.7 or less, and wherein a value (HcoA−
HcoB)/(π
a*dH/dx) is 0.8 or more, where HcoB is a coercivity of the magnetic layer B on the side near to said substrate at 0K as obtained by extrapolating values thereof at 200K and 100K, HcoA is a coercivity of the magnetic layer A on the side far from said substrate at 0K as obtained by extrapolating values thereof at 200K and 100K, dH/dx is a derivative in a track direction of a track direction component of a magnetic field from a magnetic recording head used together with said magnetic recording medium in a magnetic recording/playback device, taken in a position where said track direction component is HcoA in the center of the track and the center of the thickness direction of said magnetic layer A, and π
a is a magnetic transition width of an isolated transition formed on said magnetic recording medium using said magnetic recording head.- View Dependent Claims (6, 17)
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7. A thin film magnetic recording medium, having:
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at least 2 magnetic layers formed on a non-magnetic substrate; and
a non-magnetic intermediate layer that is interposed between said magnetic layers and causes magnetizations of said magnetic layers to be anti-parallel to one another;
wherein a ratio KuB/KuA of a magnetic anisotropy energy KuB of a magnetic layer on a side near to said substrate to a magnetic anisotropy energy KuA of a magnetic layer on a side far from said substrate is 0.7 or less. - View Dependent Claims (8)
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9. A thin film magnetic recording medium, having:
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at least 2 magnetic layers formed on a non-magnetic substrate; and
a non-magnetic intermediate layer that is interposed between said magnetic layers and causes magnetizations of said magnetic layers to be anti-parallel to one another;
wherein a ratio HkB/HkA of an anisotropic magnetic field strength HkB of a magnetic layer on a side near to said substrate to an anisotropic magnetic field strength HkA of a magnetic layer on a side far from said substrate is 0.7 or less, and wherein during a process in which, at a temperature of 30K, a magnetic field is applied in a track direction to cause magnetic saturation, then the magnetic field is reduced at a rate of 3,000A/m per second, and then a magnetic field is applied in an opposite direction to cause magnetic saturation, the derivative of magnetization with respect to magnetic field strength has at least 2 peaks, and the magnetic field strengths giving said peaks are all in said direction of the last magnetic saturation. - View Dependent Claims (10)
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11. A thin film magnetic recording medium, having:
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at least 2 magnetic layers formed on a non-magnetic substrate; and
a non-magnetic intermediate layer that is interposed between said magnetic layers and causes magnetizations of said magnetic layers to be anti-parallel to one another;
wherein a ratio HkB/HkA of an anisotropic magnetic field strength HkB of a magnetic layer on a side near to said substrate to an anisotropic magnetic field strength HkA of a magnetic layer on a side far from said substrate is 0.7 or less, and wherein said magnetic recording medium comprises at least 2 magnetic layers formed on a non-magnetic substrate; and
a non-magnetic intermediate layer that is interposed between said magnetic layers and causes magnetizations of said magnetic layers to be anti-parallel to one another, and wherein a saturation magnetization of said magnetic layer on a side near to said substrate is larger than a saturation magnetization of said magnetic layer on a side far from said substrate.
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Specification