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 each 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 spacer rings brought into contact with the magnetic recording media with the substrate having the higher rigidity have a thermal expansion coefficient different from a thermal expansion coefficient of the other spacer rings.

A magnetic stack includes a substrate and a soft magnetic underlayer deposited on a top surface of the substrate. A heat sink layer is disposed on top of the soft magnetic underlayer, and an interlayer is deposited on top of the heat sink layer. A non-magnetic seed layer is deposited on top of the interlayer. A magnetic recording structure which includes more than one magnetic recording layer is deposited on the top surface of the non-magnetic seed layer.

Provided is a magnetic tape cartridge of a single reel type in which a magnetic tape is wound around a reel, in which the magnetic tape includes a non-magnetic support and a magnetic layer containing a ferromagnetic powder, and has a tape thickness of 5.3 μm or less, the magnetic layer includes a plurality of servo bands, and a difference (G.sub.inner−G.sub.outer) between a servo band interval G.sub.inner in a range of 49 m to 51 m from a tape inner end and a servo band interval G.sub.outer in a range of 49 m to 51 m from a tape outer end is −3.9 μm to −1.1 μm as a value measured on 100th day from a date of magnetic tape cartridge manufacture.

A heat-assisted magnetic recording (HAMR) medium has a multilayered or laminated heat-sink structure. The laminated heat-sink structure includes a first heat-sink layer and a RuAl—X thermal barrier layer between the medium substrate and the first heat-sink layer. The laminated heat-sink structure may include a second heat-sink layer may between the substrate and the RuAl—X thermal barrier layer. In the RuAl—X thermal barrier layer, X is selected from C and one or more oxides of Si, Ti, W, Zr and Hf. The HAMR medium with the laminated heat-sink structure reduces the amount of required laser current as compared to a similar HAMR medium with a conventional single heat-sink layer of the same thickness, while also slightly improving magnetic properties and recording performance.

A method of forming a thin film structure involves performing one or more repetitions to form a template on a wafer. The repetitions include: depositing a layer of a template material to a first thickness T1; and ion beam milling the layer of the template material to remove thickness T2, where T2<T1, resulting in a layer of the template material with thickness T1−T2. The ion beam milling is performed at a channeling angle relative to a deposition plane of the wafer, the channeling angle defined relative to a channeling direction of a crystalline microstructure of the template material. After the repetitions, additional material is deposited on the template to form a final structure. The additional material has a same crystalline microstructure as the template material.

A magnetic recording medium includes a long-shaped base substrate having flexibility, a soft magnetic layer, and a magnetic recording layer. A squareness ratio in a longitudinal direction of the base substrate is equal to or less than a squareness ratio in a short-side direction of the base substrate. The squareness ratio in the longitudinal direction of the base substrate is 30% or less.

The magnetic tape has a magnetic layer containing ferromagnetic powder and binder on one surface of a nonmagnetic support and has a backcoat layer containing nonmagnetic powder and binder on the other surface thereof, wherein the thickness of the backcoat layer is less than or equal to 0.20 μm, and the contact angle for 1-bromonaphthalene that is measured on the surface of the backcoat layer falls within a range of 10.0° to 30.0°.

The magnetic tape has a magnetic layer containing ferromagnetic powder, abrasive, and binder on a nonmagnetic support, wherein the centerline average surface roughness Ra measured on the surface of the magnetic layer is less than or equal to 1.8 nm, the contact angle for 1-bromonaphthalene that is measured on the surface of the magnetic layer falls within a range of 45.0° to 60.0°, and the coefficient of friction that is measured on the base portion of the surface of the magnetic layer is less than or equal to 0.35.

The magnetic tape has a magnetic layer containing ferromagnetic powder, abrasive, and binder on a nonmagnetic support, wherein the centerline average surface roughness Ra measured on the surface of the magnetic layer is less than or equal to 1.8 nm, the contact angle for 1-bromonaphthalene that is measured on the surface of the magnetic layer falls within a range of 45.0° to 60.0°, and the coefficient of friction that is measured on the base portion of the surface of the magnetic layer is less than or equal to 0.35.

The magnetic tape has a magnetic layer containing ferromagnetic powder and binder on one surface of a nonmagnetic support and has a backcoat layer containing nonmagnetic powder and binder on the other surface thereof, wherein the thickness of the backcoat layer is less than or equal to 0.20 μm, the contact angle for 1-bromonaphthalene that is measured on the surface of the backcoat layer falls within a range of 10.0° to 30.0°, and the contact angle for 1-bromonaphthalene that is measured on the surface of the magnetic layer falls within a range of 45.0° to 55.0°.