A stack includes a substrate, a magnetic recording layer having a columnar structure, and an interlayer disposed between the substrate and the magnetic recording layer. The columnar structure includes magnetic grains separated by a crystalline segregant or a combination of crystalline and amorphous segregants.

A stack includes a substrate, a magnetic recording layer having a columnar structure, and an interlayer disposed between the substrate and the magnetic recording layer. The columnar structure includes magnetic grains separated by a crystalline segregant or a combination of crystalline and amorphous segregants.

A magnetic device including: a magnetic reader; a magnetic writer; and a variable overcoat, the variable overcoat positioned over at least the magnetic reader and writer, the variable overcoat having an overcoat layer, the overcoat layer having a substantially constant thickness and material; and at least one disparate overcoat portion, the disparate overcoat portion having a different thickness, a different material, or both, than the overcoat layer.

A magnetic device including: a magnetic reader; a magnetic writer; and a variable overcoat, the variable overcoat positioned over at least the magnetic reader and writer, the variable overcoat having an overcoat layer, the overcoat layer having a substantially constant thickness and material; and at least one disparate overcoat portion, the disparate overcoat portion having a different thickness, a different material, or both, than the overcoat layer.

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 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.

An e-type iron-based oxide magnetic particle powder has narrow particle size distribution and has a low content of fine particles which do not contribute to magnetic recording characteristics. As a result, a narrow coercive force distribution is achieved and the powder is suitable for increasing recording density of a magnetic recording medium. The powder containing substituting metal elements can be obtained by: adding an alkali to an aqueous solution containing trivalent iron ions and ions of the metals for partially substituting Fe sites to neutralize the aqueous solution to a pH of 1.5 to 2.5; then adding a hydroxycarboxylic acid; further adding the alkali to neutralize the aqueous solution to a pH of 8.0 to 9.0; washing with water a precipitation of an iron oxyhydroxide containing the substituting metal elements produced; and coating the iron oxyhydroxide containing the substituting metal elements with a silicon oxide and heating the resultant.

The hexagonal ferrite powder has an activation volume of greater than or equal to 800 nm.sup.3 but less than 1,200 nm.sup.3, a rare earth atom content falling within a range of 0.5 to 8.0 atom % per 100 atom % of iron atoms, and a localized presence of rare earth atoms in the surface layer portion, as well as is in the form of ellipsoidal powder.

A stack includes a substrate, a magnetic recording layer comprising FePtX disposed over the substrate, and a capping layer disposed on the magnetic recording layer. The capping layer comprises Co; at least one rare earth element; one or more elements selected from a group consisting of Fe and Pt; and an amorphizing agent comprising one to three elements selected from a group consisting of B, Zr, Ta, Cr, Nb, W, V, and Mo.

A heat-assisted magnetic recording (HAMR) medium includes a substrate, a split heat-sink structure (SHSS) and a magnetic recording layer. The SHSS includes a first heat-sink layer disposed on the substrate, a heat-sink break layer (HSBL) disposed on the first heat-sink layer, and a second heat-sink layer disposed on the HSBL. The magnetic recording layer is disposed on the SHSS. The SHSS is configured to enable use of a reduced operating current of the laser while maintaining about the same write performance properties as a thermal barrier layer, heat-assisted magnetic recording (TBLHAMR) medium that includes a thermal barrier layer (TBL) and a heat-sink layer that is greater than about 20% thicker than the thickness of the SHSS. A HAMR data storage device that incorporates the HAMR medium within a HAMR disk, and a method for making the HAMR medium are also described.