Abstract: A magnetic recording medium has a non-magnetic under-layer, a magnetic layer, a protective film and a liquid lubricant layer sequentially laminated on a non-magnetic substrate. The magnetic layer has a multi-layer structure laminated with two or more magnetic layer components, each of the magnetic layer components having ferromagnetic grains and non-magnetic grain boundaries surrounding the grain. The resulting magnetic recording medium has a granular magnetic layer exhibiting very high Hc accompanying high density of magnetic recording, while decreasing the amount of platinum needed for attaining the high Hc, and reducing media noise accompanying the high recording density.

Abstract: In a magnetic recording medium, a plurality of non-magnetic metallic intermediate layers is laminated between an under-layer and a magnetic layer. One of the intermediate layers is composed of at least an element selected from the group consisting of Ru, Re and Os and contains oxygen, and another is composed of a CoCr alloy containing at least an element selected from the group consisting of Nb, Mo, Ru, Rh, Pd, Ta, W, Re Os, Ir and Pt. The resulting magnetic recording medium provides reduced costs and improved recording characteristics.

Abstract: The present invention provides a sputtering target for production of a magnetic recording medium including at least a nonmagnetic undercoat layer, a magnetic layer, and a protective layer laminated sequentially on a nonmagnetic substrate, the sputtering target being used for film formation of the magnetic layer, the sputtering target comprising a mixture of a metal and an oxide, and the particle diameter of the oxide in the sputtering target being 10 &mgr;m or less. The sputtering target suppresses abnormal discharge occurring during film formation of a granular magnetic layer of the magnetic recording medium, and suppresses occurrence of foreign objects on the magnetic recording medium.

Abstract: The present invention provides a magnetic recording medium including at least a nonmagnetic undercoat layer, a nonmagnetic metallic intermediate layer, a magnetic layer, a protective film, and a liquid lubricant layer sequentially laminated on a nonmagnetic substrate, wherein the magnetic layer contains crystal grains having ferromagnetism and nonmagnetic grain boundaries surrounding the crystal grains, and the nonmagnetic metallic intermediate layer contains at least one layer, and the crystal structure of each layer being a hexagonal close-packed structure; and a method for producing the magnetic recording medium. The magnetic recording medium shows high coercive force Hc and a low medium noise, and its manufacturing cost is also low.

Abstract: The present invention provides a sputtering target for production of a magnetic recording medium including at least a nonmagnetic undercoat layer, a magnetic layer, and a protective layer laminated sequentially on a nonmagnetic substrate, the sputtering target being used for film formation of the magnetic layer, the sputtering target comprising a mixture of a metal and an oxide, and the particle diameter of the oxide in the sputtering target being 10 &mgr;m or less. The sputtering target suppresses abnormal discharge occurring during film formation of a granular magnetic layer of the magnetic recording medium, and suppresses occurrence of foreign objects on the magnetic recording medium.

Abstract: A magnetic recording medium has at least a non-magnetic under-layer, a magnetic layer, a protective layer and a liquid lubricant layer sequentially laminated on a non-magnetic substrate. The magnetic layer includes ferromagnetic grains and non-magnetic grain boundaries formed of metallic oxide or carbide surrounding the ferromagnetic grains. A non-magnetic intermediate layer, having grains of non-magnetic substance and non-magnetic grain boundaries, formed of metallic oxide or carbide, surrounding the grains of non-magnetic substance, is provided between the non-magnetic under-layer and the magnetic layer. The resulting magnetic recording medium exhibits a high coercive force, Hc, and low noise. Furthermore, the resulting magnetic recording medium prevents the deterioration of the media characteristics in an initial growth region in the granular magnetic layer.

Abstract: A magnetic recording medium for perpendicular magnetic recording system includes a nonmagnetic substrate and layers sequentially laminated on the substrate. The layers include a seed layer comprised of a metal or an alloy with a face centered cubic crystal structure, a nonmagnetic underlayer of a metal or an alloy with a hexagonal closest packed crystal structure, a magnetic layer having a granular structure including ferromagnetic crystalline grains with a hexagonal closest packed structure and nonmagnetic grain boundary region of mainly oxide surrounding the crystalline grains, a protective layer, and a liquid lubricant layer.

Abstract: A magnetic recording medium achieves excellent noise reduction by controlling the crystal orientation of a magnetic layer without thermal processing. The magnetic recording medium includes multiple layers laminated to a substrate. These layers include at least the magnetic layer and a non-magnetic under layer. The magnetic layer has a granular structure consisting of ferromagnetic grains with a hexagonal close-packed structure and non-magnetic grain boundaries composed mainly oxide or a nitride. The non-magnetic under-layer is a material having a body centered cubic crystal structure with a preferential orientation along a (200) plane parallel to a film surface of the under-layer.

Abstract: A magnetic recording medium which includes a non-magnetic base layer having layered upon it, in sequence, a non-magnetic middle layer and a magnetic layer. The magnetic layer has ferromagnetic crystal grains surrounded by non-magnetic grain boundaries. The non-magnetic middle layer is formed of a non-magnetic oxide or nitride, and is disposed between the non-magnetic base layer and the magnetic layer. The non-magnetic oxide or nitride in the middle layer forms a fine, island-like film. At the time of film formation of the granular magnetic layer on the middle layer, this island-like film performs stationing for the ferromagnetic crystal grains and the growth nucleus for the non-magnetic grain boundary. As a result, fine dispersion of the ferromagnetic crystal grains in the granular magnetic layer is hastened, and a high coercivity is obtained even with a small Pt composition ratio. The available reduction in Pt composition ratio reduces the cost of the magnetic recording medium.

Abstract: A magnetic recording medium exhibiting low noise and having a sufficiently high coercive force includes a magnetic layer having a granular structure including ferromagnetic crystal grains with a hexagonal closest packed structure and a nonmagnetic grain boundary region of mainly an oxide intervening between the crystal grains. An underlayer has a body-centered cubic lattice structure. A nonmagnetic intermediate layer with the hexagonal closest packed structure includes Ru, Os, and/or Re, which are provided between the magnetic layer and the underlayer. A degree of mismatching &Dgr;=|d1−d2|/d1 is at most 10%, for instance, in a range from 2.5% to 7.0%, where d1 is a spacing of lattice planes of the crystal grains in the magnetic layer and d2 is a spacing of the lattice planes of the crystal grains in the intermediate layer.

Abstract: A magnetic recording medium is provided that exhibits excellent magnetic and electromagnetic conversion characteristics and allows stable high density recording with little effect of thermal disturbances. Specifically, a magnetic recording medium uses a substrate of plastic resin, such as polycarbonate or polyolefin, not subjected to intentional heating. A magnetic layer has a granular structure consisting of ferromagnetic crystalline grains with hexagonal closest packed structure and nonmagnetic grain boundary region of mainly oxide intervening between the ferromagnetic crystalline grains. An underlayer has a body centered cubic structure. A nonmagnetic intermediate layer with a hexagonal closest packed structure is provided between the magnetic layer 4 and the underlayer. The intermediate layer is composed of a nonmagnetic metallic substance of substantially one or more elements selected from Ru, Os, and Re.

Abstract: The quantity of oxide contained in a magnetic layer is controlled to control the crystal grains and the segregation structure for ensuring low noise characteristic in a granular magnetic layer of a perpendicular magnetic recording medium. The granular magnetic layer consists of ferromagnetic crystal grains and a nonmagnetic grain boundary region mainly of an oxide surrounding the ferromagnetic crystal grains. The perpendicular magnetic recording medium has a nonmagnetic underlayer composed of a metal or alloy having hexagonal closest-packed crystal structure. The ferromagnetic crystal grain is composed of an alloy containing at least cobalt and platinum. The volume proportion of the nonmagnetic grain boundary region mainly of the oxide falls within a range of 15% to 40% of the volume of the total magnetic layer.

Abstract: A magnetic recording medium, and method of manufacturing the same, is provided with excellent recording performance by employing a granular magnetic layer having a specified composition. A magnetic recording medium according to the present invention comprises a nonmagnetic underlayer, a granular magnetic layer, a protective film, and a liquid lubrication layer sequentially laminated on a nonmagnetic substrate. The granular magnetic layer consists of ferromagnetic crystal grains containing cobalt and nonmagnetic grain boundary region surrounding the ferromagnetic crystal grains. The ferromagnetic crystal grains contain platinum in the range of 15 at % to 17 at %.

Abstract: A perpendicular magnetic recording medium has a nonmagnetic substrate, a nonmagnetic underlayer, a magnetic layer, a protective film, and a liquid lubrication layer sequentially laminated on the substrate. The nonmagnetic layer is composed of a metal or alloy having a hcp crystal structure. The magnetic recording layer consists of ferromagnetic crystal grains and a nonmagnetic grain boundary phase mainly composed of an oxide surrounding the grains. A seed layer of a metal or alloy having a fcc crystal structure can be provided under the nonmagnetic underlayer, and a nonmagnetic alignment control layer can be provided under the seed layer. The recording medium can provide high output and low noise by improving the alignment of the magnetic recording layer, reducing the initial growth layer in the magnetic recording layer, and minimizing the grain size of the magnetic recording layer.

Abstract: In a longitudinal magnetic recording medium and a method to manufacture the medium, employing a granular magnetic layer minimizes magnetic particles, resistance to thermal fluctuation is superior, and as a result, SNR is enhanced. The longitudinal magnetic recording medium includes a nonmagnetic underlayer, a nonmagnetic intermediate layer, a magnetic stabilizing layer, a nonmagnetic metallic spacer layer, a magnetic layer, a protective film layer, and a liquid lubricant layer, which are sequentially laminated on a nonmagnetic substrate. The magnetic layer has a granular structure including ferromagnetic crystal grains with a hexagonal closest packed structure and a nonmagnetic grain boundary region surrounding the grains and including an oxide. The stabilizing layer and the magnetic layer are antiferromagnetically coupled to one another through the spacer layer.

Abstract: A magnetic recording medium according to the invention includes a plastic substrate, a non-magnetic under-layer on the substrate, a magnetic layer including cobalt on the under-layer, a protective film on the magnetic layer, and a liquid lubricant layer on the protective film. The under-layer is composed of a chromium alloy having a body centered cubic lattice structure, and containing at least one element selected from the group consisting of Zr, Nb, Mo, Ru and Pd in a total amount of at least 15 at %, or containing at least one element selected from the group consisting of Hf, Ta, W, Re, Pt and Au in a total amount of at least 10 at %. The amount of cobalt dissolved out of the magnetic layer is limited by performing sputtering deposition of at least the magnetic layer at low pressures of argon.

Abstract: A magnetic recording medium has a nonmagnetic substrate, a nonmagnetic underlayer containing at least one metal selected from Ru, Os, and Re laminated on the substrate, and a magnetic layer including ferromagnetic crystal grains and nonmagnetic grain boundaries surrounding the ferromagnetic crystal grains laminated on the underlayer. The underlayer is deposited in a gas atmosphere containing argon and at least one of krypton and xenon in an amount sufficient to reduce the argon remaining in the underlayer to less than 1,000 ppm. Such a gas atmosphere contains at least 10% of krypton or xenon, and pressurized to a range of 30-70 mTorr. The underlayer is formed having film structure composed of fine particles, which is suitable for controlling the structure of the magnetic layer.

Abstract: A magnetic recording medium and manufacture method therefore and magnetic recording apparatus include a nonmagnetic base layer, a nonmagnetic intermediate layer, and a magnetic layer. The nonmagnetic base layer, the nonmagnetic intermediate layer, and the magnetic layer are sequentially stacked on a nonmagnetic substrate to control a partial pressure of H2O in an Ar atmosphere during film formation to make crystal grains of the magnetic layer finer, to obtain a uniform grain size, and to exhibit ferromagnetism and a nonmagnetic grain boundary surrounding the fine crystal grains.

Abstract: A magnetic recording medium and a manufacturing method therefore includes a protective film, a nonmagnetic substrate, a nonmagnetic base layer, a nonmagnetic intermediate layer, a magnetic layer, and a liquid lubricant layer. The nonmagnetic base layer has a body-centered cubic structure and a (200) plane including a crystal-orientation parallel with a surface of the protective film. The nonmagnetic intermediate layer has a hexagonal close-packed structure and a (110) plane including a crystal-orientation parallel with the surface of the protective film. The magnetic layer has a granular structure including hexagonal close-packed ferromagnetic crystal grains and oxide-based nonmagnetic grain boundaries surrounding the ferromagnetic crystal grains. The nonmagnetic base layer, the nonmagnetic intermediate layer, the magnetic layer, the protective film, and the liquid lubricant layer are sequentially stacked on the nonmagnetic substrate.

Abstract: A perpendicular magnetic recording medium has a granular magnetic layer and a nonmagnetic underlayer of a metal or an alloy having a hexagonal closest-packed (hcp) crystal structure. A seed layer of a metal or an alloy of a face-centered cubic (fcc) crystal structure is provided under the nonmagnetic underlayer. Such a perpendicular magnetic recording medium exhibits excellent magnetic characteristics even when the thickness of the underlayer or the total thickness of the underlayer and the seed layer is very thin. Excellent magnetic characteristics can be obtained even when of the substrate is not preheated. Accordingly, a nonmagnetic substrate, such as a plastic resin can be employed to reduce the manufacturing cost.