Abstract: A magnetic recording medium exhibits a high coercive force and suppresses noises caused therefrom at a low level. The magnetic recording medium includes a nonmagnetic substrate, a nonmagnetic undercoating layer on the substrate where the undercoating layer has a hexagonal close packing structure or a combination of the hexagonal close packing structure and a body center cubic structure. The magnetic recording medium includes a nonmagnetic intermediate layer on the undercoating layer, where the intermediate layer has a hexagonal close packing structure or a combination of the hexagonal close packing structure and a body center cubic structure, and a magnetic layer on the intermediate layer. The magnetic layer has a granular structure formed of ferromagnetic crystal grains and oxide grain boundaries or nitride grain boundaries surrounding the ferromagnetic crystal grains.

Abstract: A manufacturing method achieves excellent magnetic recording characteristics by sequentially sputtering a non-magnetic under-layer, a non-magnetic intermediate layer, and a magnetic layer on a non-magnetic substrate in an atmosphere of H2O partial pressure of 2×10−10 Torr or lower. This process allows beneficial deposition of the magnetic layer and reduces raw materials costs. The magnetic layer includes ferromagnetic grains and non-magnetic grain boundaries. The intermediate layer has a hexagonal close-packed crystal structure. The manufacturing method allows manufacture of a high quality magnetic recording medium without a heating step thereby allowing use of lower cost materials, reduces manufacturing time, and increases savings.

Abstract: A substrate for a perpendicular magnetic recording medium has a soft magnetic underlayer that functions as a soft magnetic backing layer of a perpendicular magnetic recording medium. The substrate for a perpendicular magnetic recording medium has a nonmagnetic base made of Al—Mg alloy or the like. The soft magnetic underlayer is formed of a Ni—P alloy containing phosphorus in a range of 0.5 wt % to 6 wt % formed by electroless plating on the nonmagnetic base. The substrate can also include a nonmagnetic underlayer formed by electroless plating on the base before electroless plating the soft magnetic underlayer. To form the perpendicular magnetic recording medium, the surface of the soft magnetic is textured using free abrasive grains. Thereafter, a nonmagnetic seed layer, a magnetic recording layer, and a protective layer can be formed by sputtering. A soft magnetic supplemental layer also can be formed on the soft magnetic underlayer before forming the seed layer.

Abstract: A nonmagnetic foundation layer is made to have a body-centered cubic crystal structure with a preferred crystal orientation plane being the bcc (110) plane. A nonmagnetic intermediate layer, provided between the foundation layer and a granular magnetic layer, has a hexagonal close-packed structure with the hcp (100) plane or the hcp (200) plane being the preferred orientation plane. Furthermore, the crystal lattice misfit amount between the nonmagnetic intermediate layer 3 and the granular magnetic layer is made to be not more than 10% for each of an a-axis and a c-axis. As a result, epitaxial growth of ferromagnetic crystals in the granular magnetic layer, which has an hcp structure, is promoted, and hence the crystallinity of the magnetic layer is increased, and thus it becomes possible to simultaneously realize an increase in coercivity and a reduction in noise. Depositing the layers on an unheated substrate yields reduces manufacturing costs.

Abstract: A magnetic recording medium includes a magnetic recording layer composed of an L10 type ordered alloy at a low temperature. The magnetic recording layer of the L10 type ordered alloy exhibits high magnetic anisotropy energy Ku that is necessary for compatibility between improvement in thermal stability and reduction of noises. Specifically, the recording medium includes a nonmagnetic substrate, a nonmagnetic underlayer, a magnetic recording layer, a protective layer, and a liquid lubricant layer sequentially formed on the substrate. The magnetic recording layer is formed by alternately depositing an iron or cobalt layer having thickness in a range of 0.1 nm to 0.3 nm and a platinum layer having thickness of in a range of 0.15 nm to 0.35 nm repetitively. The magnetic recording layer is mainly composed of an alloy of FePt or CoPt that includes a region with an L10 type ordered structure.

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.

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: A perpendicular magnetic recording medium has a nonmagnetic substrate having concave portions and a soft magnetic layer on the nonmagnetic substrate. The depth of the concave portion and the thickness of the soft magnetic layer are larger than at least the length and the width of the concave portion such that the easy axis of magnetization in the regions of the soft magnetic layer in the concave portions is oriented perpendicular to the soft magnetic layer due to shape magnetic anisotropy. The easy axis of magnetization oriented perpendicular to the soft magnetic layer facilitates signal generation. The recording medium does not use the magnetization of the magnetic recording layer for such signal generation, which can be head positioning signals or other signals, such as copyright data. Instead, it uses the magnetization in the concave regions of the soft magnetic layer for such signal generation.

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: A perpendicular magnetic recording medium is formed of a soft magnetic layer, an anti-ferromagnetic layer, a magnetic recording layer, a protective layer, and a liquid lubricant layer deposited in that order on a non-magnetic substrate. The anti-ferromagnetic layer is a Mn alloy containing at least Co at 10 atomic % or greater and 50 atomic % or less or a Mn alloy containing at least Ir at 10 atomic % or greater and 30 atomic % or less. A radial magnetic field is applied during formation of the anti-ferromagnetic layer and the soft magnetic layer. Exchange coupling with the anti-ferromagnetic layer controls magnetic domain walls of the soft magnetic layer. The need for heat treatment after film formation is eliminated.

Abstract: A perpendicular magnetic recording medium, which suppresses generation of spike noises, has a soft magnetic backing layer constructed of a laminated structure. The backing layer has at least one nonmagnetic metal layer at most 5 nm thick and at least two soft magnetic layers each at least 10 nm thick being alternately laminated, with the top layer and the bottom layer being the soft magnetic layers. The nonmagnetic metal layer is composed of a metal selected from Cu, Ru, Rh, Pd, Re, Os, Ir, Pt, and Au, or an alloy of these metals. The directions of magnetization in the two soft magnetic layers sandwiching the nonmagnetic metal layer are parallel to the plane of the soft magnetic layer and different from each other by 180 degrees, and the two soft magnetic layers are antiferromagnetically coupled. This structure prevents formation of magnetic domain walls when an external magnetic field is applied, thus suppressing spike noises.

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 perpendicular magnetic recording medium is formed of a soft magnetic layer, an anti-ferromagnetic layer, a magnetic recording layer, a protective layer, and a liquid lubricant layer deposited in that order on a non-magnetic substrate. The anti-ferromagnetic layer is a Mn alloy containing at least Co at 10 atomic % or greater and 50 atomic % or less or a Mn alloy containing at least Ir at 10 atomic % or greater and 30 atomic % or less. A radial magnetic field is applied during formation of the anti-ferromagnetic layer and the soft magnetic layer. Exchange coupling with the anti-ferromagnetic layer controls magnetic domain walls of the soft magnetic layer. The need for heat treatment after film formation is eliminated.

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: 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 perpendicular magnetic recording medium is formed of a soft magnetic layer, an anti-ferromagnetic layer, a magnetic recording layer, a protective layer, and a liquid lubricant layer deposited in that order on a non-magnetic substrate. The anti-ferromagnetic layer is a Mn alloy containing at least Co at 10 atomic % or greater and 50 atomic % or less or a Mn alloy containing at least Ir at 10 atomic % or greater and 30 atomic % or less. A radial magnetic field is applied during formation of the anti-ferromagnetic layer and the soft magnetic layer. Exchange coupling with the anti-ferromagnetic layer controls magnetic domain walls of the soft magnetic layer. The need for heat treatment after film formation is eliminated.