Abstract: The present invention relates to a molded ferrite sheet having opposing surfaces and a thickness in a range of 30 ?m to 430 ?m, at least one surface of said opposing surfaces having the following surface roughness characteristics (a) to (c): (a) a center line average roughness is in a range of 170 nm to 800 nm, (b) a maximum height is in a range of 3 ?m to 10 ?m, and (c) an area occupancy rate of cross-sectional area taken along a horizontal plane at a depth of 50% of the maximum height in a square of side 100 ?m is in a range of 10 to 80%.

Abstract: The present invention relates to a molded ferrite sheet having opposing surfaces and a thickness in a range of 30 ?m to 430 ?m, at least one surface of said opposing surfaces having the following surface roughness characteristics (a) to (c): (a) a center line average roughness is in a range of 170 nm to 800 nm, (b) a maximum height is in a range of 3 ?m to 10 ?m, and (c) an area occupancy rate of cross-sectional area taken along a horizontal plane at a depth of 50% of the maximum height in a square of side 100 ?m is in a range of 10 to 80%.

Abstract: A magnetic recording medium comprises a polymer film substrate having an elongated shape or a polymer flexible substrate; an underlayer having a thickness of less than 10 nm, which is formed on the substrate; and a magnetic recording layer comprising a spinel iron oxide thin film containing maghemite as a main component, which is formed on the underlayer and has a coercive force of not less than 159 kA/m (2000 Oe). The present invention provides the magnetic recording medium comprising a spinel iron oxide thin film containing maghemite as a main component, which exhibits an excellent recording resolution performance while maintaining a high coercive force and a high coercive force squareness.

Abstract: A perpendicular magnetic recording medium, comprises a substrate; a soft-magnetic layer formed on the substrate; an NaCl-type oxide layer for orientation control formed on the soft-magnetic layer, having a thickness of from more than 0 to less than 10 nm; and a magnetic recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film. Such a perpendicular magnetic recording medium is capable of showing excellent magnetic properties, a high recording resolution and improved surface properties.

Abstract: A magnetic recording medium exhibiting a high coercive force and excellent squareness having a substrate, an underlayer formed on the substrate, and a spinel-type iron oxide thin film with maghemite as a main component formed on the underlayer. The spinel-type iron oxide thin film has a thickness (t) of 5 to 50 nm, is constituted by grains having an average grain size (D) of 5 to 30 nm, standard deviation of sizes of grain of not more than 4 nm and a ratio (D/t) of the average grain size (D) to the thickness (t) of less than 1.0, exhibits a coercive force of not less than 159 kA/m (2,000 Oe) and a coercive squareness ratio S* of not less than 0.5:1 in a longitudinal recording medium or a squareness ratio not less than 0.75:1 in a perpendicular recording medium.

Abstract: A perpendicular magnetic recording medium, comprises a substrate; a soft-magnetic layer formed on the substrate; an NaCl-type oxide layer for orientation control formed on the soft-magnetic layer, having a thickness of from more than 0 to less than 10 nm; and a magnetic recording layer formed on the NaCl-type oxide layer for orientation control, comprising a maghemite thin film. Such a perpendicular magnetic recording medium is capable of showing excellent magnetic properties, a high recording resolution and improved surface properties.

Abstract: A magnetic recording medium, comprising: a substrate; an underlayer formed on the substrate; and a spinel-type iron oxide thin film comprising maghemite as a main component formed on the underlayer,

Abstract: A magnetic recording medium is prepared by forming on a plastic substrate, a nickel oxide underlayer having a plane (200) which is predominantly oriented in parallel with the surface of the plastic substrate, then forming on the nickel oxide underlayer at a substrate temperature of less 240° C., a cobalt-containing magnetite thin film having a plane (400) which is predominantly oriented in parallel with the surface of the plastic substrate, and finally oxidizing the cobalt-containing magnetite thin film in a plasma-activated oxygen atmosphere containing a rare gas at a substrate temperature of less than 240° C. while incorporating the rare gas into oxygen. This results in a cobalt-containing maghemite thin film as a perpendicular magnetic film having a spacing of a plane (400) of not more than 2.082 Å. The magnetic recording medium so produced is useful for high-density recording using a plastic substrate.

Abstract: A magnetic recording medium comprising: a plastic substrate; a nickel oxide underlayer formed on said substrate; and a cobalt-containing maghemite thin film formed on said nickel oxide underlayer, containing cobalt at a molar ratio of cobalt to iron of 0.01:1 to 0.1:1, and having either a spacing of a plane (311) of not more than 2.510 Å, a spacing of a plane (222) of not more than 2.415 Å or a spacing of a plane (220) of not more than 2.950 Å, a ratio value of an X-ray diffraction pattern peak intensity of either of the planes (311), (222) and (220) of said cobalt-containing maghemite thin film to an X-ray diffraction pattern peak intensity of the plane (400) thereof being more than 0.5. Such magnetic recording medium suitably applicable to existent magnetic recording systems using a ring-type magnetic head and capable of using a plastic substrate for providing a magnetic recording medium for high-density recording.

Abstract: A magnetic recording medium of the present invention comprises: a plastic substrate; and a cobalt-containing maghemite thin film formed on said substrate, containing cobalt at a molar ratio of cobalt to iron of not more than 0.06:1, and having either a spacing of a plane (311) of not more than 2.510 Å, a spacing of a plane (222) of not more than 2.415 Å or a spacing of a plane (220) of not more than 2.950 Å; and has a coercive force of not less than 2,000 Oe. Such magnetic recording medium suitably applicable to existent magnetic recording systems using a ring-type magnetic head and capable of using a plastic substrate for providing a magnetic recording medium for high-density recording.

Abstract: A magnetic recording medium of the present invention comprises:a substrate; anda cobalt-containing maghemite thin film formed on said substrate, containing cobalt at a molar ratio of cobalt to iron of not more than 0.06:1, having either a spacing of a (311) plane of not more than 2.510 .ANG., a spacing of a (222) plane of not more than 2.415 .ANG. or a spacing of a (220) plane of not more than 2.950 .ANG., and having a coercive force of not less than 1,800 Oe.Such a magnetic recording medium has as high a coercive force as possible, specifically not less than 1,800 Oe, and exhibits an excellent stability independent to change in passage of time and a large output in a high recording frequency region.

Abstract: A magnetic recording medium of the present invention comprises:a substrate;a nickel oxide underlayer formed on said substrate; anda cobalt-containing maghemite thin film formed on said nickel oxide underlayer, having either a spacing of a (311) plane of not more than 2.510 .ANG., a spacing of a (222) plane of not more than 2.415 .ANG. or a spacing of a (220) plane of not more than 2.950 .ANG., and having the ratio of either of X-ray diffraction spectrum peak intensities of the (311), (222) or (220) planes of said cobalt-containing maghemite thin film to an X-ray diffraction spectrum peak intensity of the (400) plane of more than 0.5:1.Such a magnetic recording medium has a higher coercive force, a higher saturation magnetization, less amount of noise generated, a large output in a high recording frequency region and less distortion of a reproduced waveform, and is suitable for use in current magnetic recording systems in which a ring-type magnetic write head is used.

Abstract: The disclosure describes a magnetic recording medium comprising:a substrate;an NiO primary layer which is formed on the substrate and in which the plane (200) is substantially oriented in parallel with the surface of the substrate; anda Co-containing maghemite thin film which is formed on the NiO primary layer and in which the plane (400) is substantially oriented in parallel with the surface of the substrate, the molar ratio of Co to Fe is not less than 0.01 to less than 0.10, and the spacing of the plane (400) is not more than 2.082 .ANG..

Abstract: The disclosure describes a magnetic recording medium comprising:a substrate;an NiO primary layer which is formed on the substrate and in which the plane (200) is substantially oriented in parallel with the surface of the substrate; anda Co-containing maghemite thin film which is formed on the NiO primary layer and in which the plane (400) is substantially oriented in parallel with the surface of the substrate, the molar ratio of Co to Fe is not less than 0.01 to less than 0.10, and the spacing of the plane (400) is not more than 2.082 .ANG..

Abstract: Disclosed herein is a perpendicular magnetic film comprising a Co-containing .gamma.-Fe.sub.2 O.sub.3 film formed on a substrate in which the plane (400) is predominantly oriented in parallel with said substrate, the molar ratio of Co to Fe is between 0.01 and 0.32, the spacing of said plane (400) is not more than 2.084 .ANG., and the optical absorption coefficient at 700 nm is not more than 2.5 .mu.m.sup.-1.