Abstract: [Problem] An object is to provide a perpendicular magnetic recording medium in which a narrower track width is achieved by enhancing an exchange coupling magnetic field Hex of a soft magnetic layer so that a higher recording density can be achieved. [Solution] A perpendicular magnetic recording medium according to the present invention is configured to include a magnetic recording layer 122 that records a signal, and a soft magnetic layer 114 provided below the magnetic recording layer, on a base 110 on a main surface of which textures are formed, wherein the textures includes first textures 110a that is linear rails in a certain direction, and second textures 110b that are trails intersecting at a predetermined angle with the first textures; and the angle of intersection between the first textures and the second textures is 10° or less.

Abstract: A manufacturing method of a glass substrate for a magnetic disk is provided whereby nano pits and/or nano scratches cannot be easily produced in polishing a principal face of a glass substrate using a slurry containing zirconium oxide as an abrasive. The manufacturing method of a glass substrate for a magnetic disk includes, for instance, a polishing step of polishing a principal face of a glass substrate using a slurry containing, as an abrasive, zirconium oxide abrasive grains having monoclinic crystalline structures (M) and tetragonal crystalline structures (T).

Abstract: A glass substrate for a magnetic disk of the invention is a disk-shaped glass substrate for a magnetic disk where the substrate has a main surface and end face and is subjected to chemical reinforcement treatment, and is characterized in that the penetration length in the uppermost-portion stress layer on the main surface is 49.1 ?m or less, and that assuming that an angle between the main surface and compressive stress in the stress profile by a Babinet compensator method is ?, a value y of {12·t·ln(tan ?)+(49.1/t)} is the penetration length in the uppermost-portion stress layer or less.

Abstract: Provided are a magnetic disk substrate that can be adapted to a reduction in flying height of a head in an HDD and to an increase in rotational speed therein, and a method of manufacturing such a substrate. In an annular glass substrate for a magnetic recording medium, a main surface (12) of the glass substrate is uniformly inclined from an inner peripheral end (13) to an outer peripheral end (14) and has an isotropic shape with respect to an axis passing through the center of the glass substrate. That is, it is rotationally symmetric with respect to an arbitrary angle rotation about the axis passing through the center of the glass substrate.

Abstract: A method of manufacturing a magnetic recording medium includes the steps of forming an intermediate layer that is electrically conductive over a non-magnetic substrate; forming an aluminum-containing layer on the intermediate layer; forming a plurality of micro pits in the aluminum-containing layer; generating an alumina-containing layer by anode oxidation of the aluminum-containing layer and simultaneously forming a plurality of nano holes in the alumina-containing layer originating from the plurality of micro pits respectively to expose the intermediate layer; cleaning and drying the plurality of nano holes using a fluid selected from the group consisting of a sub- and super-critical carbon dioxide fluid; and depositing a magnetic metal selectively through the plurality of nano holes on the intermediate layer to form a plurality of magnetic recording elements that collectively form a magnetic recording layer.

Abstract: A method for forming a glass substrate comprises the steps of forming a glass blank with opposing substantially planar surfaces and at least one edge, coating the glass blank in silica-alumina nanoparticles, the silica-alumina nanoparticles comprising an inner core of silica with an outer shell of alumina, annealing the coated glass blank to form a conformal coating of silica-alumina around the glass blank, and polishing the coated glass blank to remove the conformal coating of silica-alumina from the opposing substantially planar surfaces thereof.

Abstract: A method for fabricating a glass substrate containing SiO2 as a main ingredient thereof for an information recording medium which ensures removal of abrasive or foreign mater adhered to the glass substrate without complicating a cleaning step, involves, after a polishing step, keeping the surface of the glass substrate in contact with a liquid having a Si element elution in a range from 100 to 10 000 ppb/mm2 before a scrub-cleaning step.

Abstract: A substrate for a recording medium suited for thermally assisted recording methods has a disc shape with a center hole and includes a silicon single-crystal supporting member; an SiO2 film formed on the silicon single-crystal supporting member; a main face having a film thickness of the SiO2 film thereon which is less than 10 nm; a substrate inner periphery end face adjacent to the center hole; a substrate inner periphery chamfer portion adjacent to the main face and to the substrate inner periphery end face; a substrate outer periphery end face positioned on the side of the main face opposite the substrate inner periphery end face; and a substrate outer periphery chamfer portion adjacent to the main face and to the substrate outer periphery end face. A magnetic recording medium includes at least the above substrate and a magnetic recording layer formed on the substrate.

Abstract: There is provided a glass substrate for a magnetic disk in which a maximum height of bumps forming a roughness pattern at a period of smaller than 2 ?m is 6 nm or lower in an annular area having a width of 30 ?m on a main surface on which a magnetic recording area is formed, a number of bumps having a height of 3 nm or higher in a unit area having a circular arc length of 30 ?m within the annular area is one or less, and a difference in arithmetic average roughness between unit areas within the annular area is 0.2 nm or smaller.

Abstract: A glass substrate for a magnetic disk of the invention is a disk-shaped glass substrate for a magnetic disk where the substrate has a main surface and end face and is subjected to chemical reinforcement treatment, and is characterized in that the penetration length in the uppermost-portion stress layer on the main surface is 49.1 ?m or less, and that assuming that an angle between the main surface and compressive stress in the stress profile by a Babinet compensator method is ?, a value y of {12·t·ln(tan ?)+(49.1/t)} is the penetration length in the uppermost-portion stress layer or less.

Abstract: Provided is a method of manufacturing a glass substrate efficiently via prevention of foreign matter adhesion to a glass substrate as to chemical strengthening. Disclosed is a method of manufacturing a glass substrate for a recording medium possessing the step of conducting a chemical strengthening process by which a glass substrate held by a holding jig and the holding jig are immersed in a chemical strengthening solution, and 1st alkali metal ion on a surface of the glass substrate is substituted by 2nd alkali metal ion having a larger ion diameter than that of 1st alkali metal ion contained in the chemical strengthening solution, wherein the holding jig possesses a member of material made of a metal comprising an alkali metal element, or a metal film comprising an alkali metal element to cover a surface of the holding jig from the very beginning of the chemical strengthening process.

Abstract: An inner peripheral edge of a toroidal glass substrate for a magnetic disk is subjected to mechanical polishing in such a manner that the surface roughness is no greater than 9 nm in terms of Rmax. Then, the inner peripheral edge is subjected to chemical polishing to remove at least 2 ?m of a surface layer. The inner peripheral edge has a non-conventional mirror-finished surface obtained by mechanical polishing. Thus, sufficient ring strength is obtained even when the chemical polishing depth is smaller than in the past. A polishing depth of less than 5 ?m is sufficient.

Abstract: According to one aspect of the present invention, provided is glass for use in substrate for information recording medium, which comprises, denoted as molar percentages, a total of 70 to 85 percent of SiO2 and Al2O3, where SiO2 content is equal to or greater than 50 percent and Al2O3 content is equal to or greater than 3 percent; a total of equal to or greater than 10 percent of Li2O, Na2O and K2O; a total of 1 to 6 percent of CaO and MgO, where CaO content is greater than MgO content; a total of greater than 0 percent but equal to or lower than 4 percent of ZrO2, HfO2, Nb2O5, Ta2O5, La2O3, Y2O3 and TiO2; with the molar ratio of the total content of Li2O, Na2O and K2O to the total content of SiO2, Al2O3, ZrO2, HfO2, Nb2O5, Ta2O5, La2O3, Y2O3 and TiO2 ((Li2O+Na2O+K2O)/(SiO2+Al2O3+ZrO2+HfO2+Nb2O5+Ta2O5+La2O3+Y2O3+TiO2)) being equal to or less than 0.28.

Abstract: A polymer thin film in which cylindrical phases are distributed in a continuous phase and are oriented in a pass-through-direction of the film includes at least: a first block copolymer including at least a block chain A1, as a component of the continuous phase, composed of polymerized monomers a1, and a block chain B1, as a component of the cylindrical phases, composed of polymerized monomers b1; and a second block copolymer including at least a block chain A2, as a component of the continuous phase, composed of polymerized monomers a2, and a block chain B2, as a component of the cylindrical phases, composed of polymerized monomers b2, with the second copolymer having a degree of polymerization different from that of the first copolymer. A film thickness of the polymer thin film and an average center distance between adjacent cylindrical phases have a relation represented by a predetermined expression.

Abstract: An object of the present invention is to provide a method of manufacturing a glass substrate containing alkali metals. A glass substrate manufactured by the method exhibits excellent performances including durability by virtue of suppressing elution of alkali metals. A method comprises a step of immersing a glass material in an aqueous solution containing a formate to suppress elution of component of the glass material.

Abstract: Provided are a glass substrate for an information recording medium, which has both high strength and high flatness and can be manufactured at low cost, a method for manufacturing such glass substrate and an information recording medium using such glass substrate. The glass substrate for the information recording medium satisfies inequalities of 0.1?(W1?W3)/W2?5, where, W1 is an ion concentration at the center portion in the thickness direction of the glass substrate in a chemically reinforced region at the outer circumference end surface and the inner circumference end surface of the glass substrate and is the maximum value of K+ ion concentration, W2 is a Na+ ion concentration at a position where the K+ ion concentration is maximum, and W3 is a K+ ion concentration in a glass substrate region not chemically reinforced.

Abstract: A magnetic recording medium substrate has a polyester film having metallic oxide-containing layers (layers M) formed on both the surfaces, one layer on each surface, the layers M having a thickness of 50 to 200 nm each, characterized in that the magnetic recording medium substrate has a total light transmittance of 0 to 75% and a surface resistivity of 1×102 to 1×1013? on each surface.

Abstract: In this invention, etching is not performed in the step of planarizing a polycrystalline Si wafer, but only mechanical grinding is performed for planarization. This is because, since the etching rate is crystal-face dependent, etching of the polycrystalline Si wafer unavoidably results in formation of steps due to different crystal face orientations of individual crystal grains exposed on a surface of the wafer, thus hindering precision surface planarization. Subsequently, the Si wafer surface is coated with an oxide film to form an Si wafer with oxide film prior to the final polishing stage and then a surface of the oxide film is planarized, to give a planar substrate (i.e., Si substrate with oxide film) having no step on the surface thereof.

Abstract: A method for manufacturing a magnetic recording medium disk substrate is provided for achieving a magnetic disk having a suitable surface roughness, a high in-plane magnetic anisotropy and a high S/N. The manufacturing method has a texturing process wherein the magnetic recording medium disk substrate is rotated in the circumferential direction while a polishing tape is pressed against the rotating substrate. The polishing tape includes polyester fiber having a fiber diameter of 400 nm to 950 nm, on the surface coming into contact with the substrate. All the while, slurry including abrasive grains including a cluster diamond is supplied to the surfaces of the substrate. The present invention relates to a magnetic recording medium disk substrate produced by the manufacturing method; and a magnetic recording medium at least comprising a magnetic layer on the magnetic recording medium disk substrate and manufacturing method of the magnetic recording medium.

Abstract: A substrate for use as a disk substrate in a hard disk drive or the like, an information recording medium such as a magnetic disk, and a starting material glass plate which is a starting material of the substrate for information recording media. The forming conditions of the starting material glass plate are controlled such that the starting material glass plate has a long-wavelength waviness of not more than 6 nm. This starting material glass plate is polished so as to have a long-wavelength waviness of not more than 6 nm using CeO2 abrasive grains having a mean grain diameter of not less than 0.01 ?m and a 90% diameter of the volume grain size distribution of not less than 0.02 ?m. The resulting substrate for an information recording medium has an excellent planarity, can be obtained in a short time and with a low polishing amount, and the resulting information recording medium is able to cope with increased data zone recording density.

Abstract: A process for manufacturing a glass substrate for a magnetic recording medium comprising polishing a crystallized glass substrate using abrasive grains, and then washing the substrate using an aqueous organic carboxylic acid solution; a glass substrate for a magnetic recording medium which is manufactured by the process; and a magnetic recording medium obtained using the substrate. A glass substrate for a magnetic recording medium is manufactured, whereby the surface roughness is low and the surface defects are minimal for washing after polishing of a crystallized glass substrate, and wherein the Read-Write performance are not impaired when a recording layer including a magnetic film is formed on the magnetic recording medium substrate for manufacturing a magnetic recording medium.

Abstract: According to one embodiment, a substrate for a magnetic recording media has circumferential protrusions corresponding to recording tracks and circumferential recesses corresponding to grooves between the recording tracks, in which the substrate satisfying at least one of conditions of (a) a surface of the recess has a surface energy smaller than that of the protrusion, (b) the surface of the recess is modified with a thermally decomposable or deformable substance, (c) the surface of the recess has surface roughness smaller than that of the protrusion, (d) crystal orientation is more disturbed on the surface of the recess than on the protrusion, (e) the surface of the recess is modified with a substance that causes reaction with a magnetic material or that diffuses into the magnetic material, and (f) the surface of the recess is modified with a substance soluble in a solvent or with a deformable substance.

Abstract: A magnetic recording medium including a nonmagnetic substrate and a magnetic layer, wherein the nonmagnetic substrate is made from a polyethylene naphthalate and has a thickness of 6.5 ?m or smaller, and the magnetic recording medium has a creep deformation of 0.30% or less in a longitudinal direction of the magnetic recording medium under a tensile stress of 15.7 MPa applied in the longitudinal direction at 60° C. for 50 hours.

Abstract: A storage media comprises: a substrate comprising a plastic resin portion, wherein to plastic resin portion comprises poly(arylene ether) and a styrene material selected from the group consisting of polystyrene, styrenic copolymer(s), and reaction products and combinations comprising at least one of the foregoing styrene material(s), and a data layer on the substrate. The data layer can be at least partly read from, written to, or a combination thereof by an energy field. Additionally, when the energy field contacts the storage media, the energy field is incident upon the data layer before it could be incident upon the substrate.

Abstract: The gas components in thermoplastic norbornene resin pellets are suppressed below certain levels by drying the resin under vacuum or under the ordinary pressure and under vacuum. A substrate for magnetic recording media is manufactured by injection-molding the resin dried by the method according to the invention. The magnetic recording medium, employing the substrate manufactured according to the invention, includes at least a magnetic layer, a protection layer on the magnetic layer and a liquid lubricant layer on the protection layer. The magnetic recording medium is manufactured by forming these layers, one after another, on the substrate according to the invention.

Abstract: A magnetic recording medium is disclosed that includes a substrate; an anodic alumina film formed on the substrate; a pore formed in the anodic alumina film; a carbon layer covering the surface of the anodic alumina film and the inner wall of the pore; a magnetic particle formed on the carbon layer inside the pore; and a lubrication layer covering the carbon layer and the magnetic particle.

Abstract: Disclosed are a glass substrate for an information recording medium, having excellent scratch resistance and a light weight and having high fracture toughness, the glass substrate having a fragility index value, measured in water, of 12 ?m?1/2 or less or having a fragility index value, measured in an atmosphere having a dew point of ?5° C. or lower, of 7 ?m?1/2 or less, or the glass substrate comprising, by mol %, 40 to 75% of SiO2, 2 to 45% of B2O3 and/or Al2O3 and 0 to 40% of R?2O in which R? is at least one member selected from the group consisting of Li, Na and K), wherein the total content of SiO2, B2O3, Al2O3 and R?2O is at least 90 mol %, and a magnetic information recording medium comprising a magnetic recording layer formed on the glass substrate.

Abstract: A method of manufacturing a magnetic recording medium including a servo pattern, comprising steps of: (a) providing a non-magnetic substrate including at least one major surface; (b) providing a stamper having a surface with a plurality of recesses forming a negative image of a servo pattern; (c) forming a layer of a partially dried sol-gel material having a first surface in conformal contact with the recess-patterned surface of the stamper and an exposed second surface opposite the first surface; (d) urging the major surface of the substrate into contact with the exposed second surface of the sol-gel layer; (e) removing the stamper from contact with the layer of sol-gel material to expose the recess-patterned surface thereof; (f) converting the partially dried sol-gel layer to a glass-like layer while preserving the recess pattern in the surface thereof; and (f) forming on the recess-patterned surface a laminate of layers constituting a servo-patterned magnetic recording medium.

Abstract: A carbonaceous protective layer particularly suitable for use in magnetic recording media. The carbonaceous protective layer is formed by a Filtered Cathodic Arc process, and contains nitrogen distributed therein. A process for the production of a carbonaceous protective layer as well as a magnetic recording medium and a magnetic disk apparatus are also disclosed.