A heat-assisted magnetic recording (HAMR) medium has a multilayered underlayer between the heat-sink layer and the recording layer. One embodiment of the underlayer is a multilayer of a thermal barrier layer consisting essentially of MgO and TiO, and a seed layer containing MgO and nitrogen (N) directly on the thermal barrier layer, with the recording layer on and in contact with the seed layer. The interface between the thermal barrier layer and the seed layer contains Ti and N, some of which may be present as TiN to act as a diffusion barrier to prevent diffusion of the Ti into the recording layer. The Ti-containing thermal barrier layer has a higher thermal resistivity than the conventional MgO thermal barrier/seed layer and thus allows for reduced laser power to the recording layer while still achieving a high thermal gradient at the recording layer.

There are provided: an aluminum alloy substrate for a magnetic disk, the aluminum alloy substrate including an aluminum alloy including 0.4 to 3.0 mass % (hereinafter, “%”) of Fe, less than 0.10% of Si, less than 0.10% of Mg, and the balance of Al and unavoidable impurities, in which an Al—Fe-based intermetallic compound having a longest diameter of 2 μm or more and less than 3 μm is dispersed at a distribution density of 1000 particles/mm.sup.2 or more, and a Mg—Si-based intermetallic compound having a longest diameter of 1 μm or more is dispersed at a distribution density of 1 particle/mm.sup.2 or less; a method for producing the same; and a magnetic disk in which an electroless Ni—P plating treatment layer and a magnetic layer thereon are disposed on a surface of the aluminum alloy substrate for a magnetic disk.

In one aspect, the present disclosure provides a method for producing an aluminum platter, which can improve the smoothness of the substrate surface before a magnetic layer is formed thereon and can provide a hard disk substrate that can be processed into a medium with a high yield. In another aspect, the present disclosure relates to a method for producing an aluminum platter, including the following steps 1 and 2: step 1: bringing a composition containing a compound (component A) that has at least one structure represented by the following formula (I) and has a molecular weight between 50 and 100,000 inclusive into contact with a substrate surface of a Ni—P plated aluminum alloy substrate; and step 2: forming a magnetic layer on the substrate obtained in the step 1. ##STR00001##

Provided is an aluminium alloy substrate for a magnetic disk, a method for fabricating the substrate, and a magnetic disk composed of the aluminium alloy substrate for a magnetic disk. The substrate contains an aluminium alloy composed of one or more elements selected from a group comprising 0.05 to 3.00 mass % (hereinafter abbreviated as “%”) of Fe, 0.05% to 3.00% of Mn, 0.05% to 18.00% of Si, 0.05% to 8.00% of Ni, 0.05% to 3.00% of Cr, and 0.05% to 3.00% of Zr, with a balance of Al and unavoidable impurities. The substrate has a Young modulus of 67 GPa or more in each of the 0° direction, 45° direction, and 90° direction relative to the rolling direction of the substrate.

Magnetic recording media including an interlayer configured to reduce lattice mismatch with adjacent layers of the media, such as an adjacent seed layer or an adjacent underlayer. In one example, an interlayer alloy is provided that includes tungsten (W) along with Cobalt (Co), Chromium (Cr), and Ruthenium (Ru). The atomic percentages of W and Ru within the interlayer are selected so that the amount lattice mismatch between the interlayer and its adjacent layers is below a preselected amount, such as below 3% as quantified by d-spacing. In some examples, the atomic percentage of Ru is greater than 25% and the atomic percentage of W is 2-10%. Methods of fabricating the magnetic recording media are also provided.

According to one embodiment, a disk device includes a housing, a plurality of magnetic recording media disposed in the housing in a multi-layered manner with intervals therebetween and a plurality of spacer rings, one of the spacer rings being disposed between each adjacent pair of the magnetic recording media. At least one of an uppermost magnetic recording medium and a lowermost magnetic recording medium includes a substrate having a rigidity higher than that of substrates of the other magnetic recording media, and one or more of the plurality of spacer rings is in contact with the magnetic recording media including the substrate having the higher rigidity, and has a thermal expansion coefficient different from a thermal expansion coefficient of the other spacer rings.

A magnetic disk substrate is composed of an aluminum alloy substrate, a base plating layer on a surface of the aluminum alloy substrate, and a boundary region between the aluminum alloy substrate and the base plating layer. The boundary region includes a specific boundary region (D(1).sub.I(50-84)) having Al emission intensities equal to 50% to 84% of an average Al emission intensity in an interior region of the aluminum alloy substrate in glow discharge optical emission spectroscopy in the depthwise direction from the surface of the magnetic disk substrate. The specific boundary region (D(1).sub.I(50-84)) has a maximum Fe emission intensity (I(1).sub.Fe(max)) higher than an average Fe emission intensity (I(1).sub.Fe(ave)) in the interior region of the aluminum alloy substrate in the glow discharge optical emission spectroscopy.

A tape-shaped magnetic recording medium includes a base, a nonmagnetic layer that is provided on the base and contains a nonmagnetic powder, and a magnetic layer that is provided on the nonmagnetic layer and contains a magnetic powder. In the magnetic recording medium, the magnetic layer has an average thickness of not more than 90 nm, the magnetic powder has an average aspect ratio of from 1.0 to 3.0, a coercive force Hc1 in a perpendicular direction is not more than 3,000 Oe, the coercive force Hc1 in the perpendicular direction and a coercive force Hc2 in a longitudinal direction satisfy the relation of Hc2/Hc1≤0.8, the nonmagnetic layer has an average thickness of not more than 1.1 μm, and the nonmagnetic powder has an average particle volume of not more than 2.0×10.sup.−5 μm.sup.3.

A substrate for a magnetic disk includes a substrate main body having two main surfaces, and a film that is provided on the main surfaces and is made of a material having a loss factor of 0.01 or more. The substrate for a magnetic disk including the film has a thickness T of 0.700 mm or less, and a thickness D [mm] of the film provided on the main surfaces and the thickness T [mm] of the substrate for a magnetic disk including the film satisfy a relationship D≥0.0082/T−0.0015.

An aluminum alloy sheet for a magnetic disk, a method for manufacturing same, and a magnetic disk using same. The aluminum alloy sheet is made of an aluminum alloy comprising 0.10 to 3.00 mass % of Fe, 0.003 to 1.000 mass % of Cu, and 0.005 to 1.000 mass % of Zn, with a balance of Al and unavoidable impurities, wherein a value obtained by dividing a difference in an area ratio (%) of second phase particles between a region (A) and a region (B) by an average value of area ratios (%) of second phase particles in the regions (A) and (B) is 0.05 or less, the region (A) being a region from a sheet thickness center plane to a front surface of the sheet, and the region (B) being a region from the sheet thickness center plane to a rear surface of the plate.