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.

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.

In the magnetic recording medium, a number distribution A of a plurality of bright regions, based on equivalent circle diameters thereof, in a binarized image of a secondary electron image obtained by imaging a surface of the magnetic layer by a scanning electron microscope at an acceleration voltage of 5 kV and a number distribution B of a plurality of dark regions, based on equivalent circle diameters thereof, in a binarized image of a secondary electron image obtained by imaging a surface of the magnetic layer by a scanning electron microscope at an acceleration voltage of 2 kV respectively satisfy a predetermined number distribution.

Provided are a lubricant that is highly resistant to contamination and highly thermally stable, a lubricant that is highly durable and highly heat resistant, and a magnetic disk. A fluoropolyether compound contains perfluoropolyether groups, end groups each containing at least one hydroxyl group, and a linking group that is comprised of a C.sub.4-C.sub.14 hydrocarbon group and that contains at least one hydroxyl group.

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.

A hard disk drive includes a base deck with a floor portion and a side wall portion. The floor portion extends between an upper surface and a bottom surface, and the side wall portion extends from the floor portion. A top cover is coupled to the base deck and includes a ceiling portion and a wall portion. The hard disk drive includes a weld that directly couples the wall portion of the top cover to the floor portion of the base deck.

A hard disk drive includes a base deck with a floor portion and a side wall portion. The floor portion extends between an upper surface and a bottom surface, and the side wall portion extends from the floor portion. A top cover is coupled to the base deck and includes a ceiling portion and a wall portion. The hard disk drive includes a weld that directly couples the wall portion of the top cover to the floor portion of the base deck.

A heat-assisted magnetic recording (HAMR) disk has a magnetic recording layer (typically a FePt chemically-ordered alloy), a seed-thermal barrier layer (typically MgO) below the recording layer, a heat-sink layer, and an optical-coupling multilayer of alternating plasmonic and non-plasmonic materials between the heat-sink layer and the seed-thermal barrier layer. Unlike a heat sink layer, the multilayer has very low in-plane and out-of-plane thermal conductivity and thus does not function as a heat sink layer. The multilayer's low thermal conductivity allows the multilayer to also function as a thermal barrier. Due to the plasmonic materials in the multilayer it provides excellent optical coupling with the near-field transducer (NFT) of the HAMR disk drive.

A heat-assisted magnetic recording (HAMR) disk has a magnetic recording layer (typically a FePt chemically-ordered alloy), a seed-thermal barrier layer (typically MgO) below the recording layer, a heat-sink layer, and an optical-coupling multilayer of alternating plasmonic and non-plasmonic materials between the heat-sink layer and the seed-thermal barrier layer. Unlike a heat sink layer, the multilayer has very low in-plane and out-of-plane thermal conductivity and thus does not function as a heat sink layer. The multilayer's low thermal conductivity allows the multilayer to also function as a thermal barrier. Due to the plasmonic materials in the multilayer it provides excellent optical coupling with the near-field transducer (NFT) of the HAMR disk drive.

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.