A heat-assisted magnetic recording (HAMR) media stack is provided in which Iridium (Ir)-based materials may be utilized as a secondary underlayer instead of a Magnesium Oxide (MgO) underlayer utilized in conventional media stacks. Such Ir-based materials may include, e.g., pure Ir, Ir-based alloys, Ir-based compounds, as well as a granular Ir layer with segregants. The use of Ir or Ir-based materials as an underlayer provide advantages over the use of MgO as an underlayer. For example, DC sputtering can be utilized to deposit the layers of the media stack, where the deposition rate of Ir is considerably higher than that of MgO resulting in higher manufacturing production yields. Further still, less particles are generated during Ir-based layer deposition processes, and Ir-based underlayer can act as a better heat sink. Further still, the morphology and structure of a recording layer deposited on an Ir-based layer can be better controlled.

A soft underlayer (SUL) and methods for making an SUL are provided, the SUL having characteristics that make it compatible with the high temperature requirements associated with heat-assisted magnetic recording (HAMR) media growth and writing, e.g., temperatures greater than 500° C. The SUL may have a high crystallization temperature of greater than 450° C. and a high Curie temperature greater than 300° C., for example. Additionally, the SUL can maintain a saturation magnetization value greater than, e.g., 9 kGauss, at such high temperatures, thereby having the ability to remain amorphous at temperatures up to, e.g., 650° C., and exhibiting a relatively flat integrated noise profile from approximately 300° C. to 650° C. Further still, a spacer layer material is chosen such that inter-diffusion does not occur at these high temperatures.

An ink-printed substrate comprising a substrate and water-based ink composition printed on the substrate, wherein the ink-printed substrate has an average color density of at least about 0.48 or greater.

A non-metallic media substrate includes a disc-shaped substrate body having at least one media storage surface on a face thereof. The substrate body has a center opening having an inner diameter and an outer diameter surface, and the substrate body has a thickness. The substrate further includes an annular groove at the outer diameter of the media substrate, the annular groove having chamfered edges and an internal concavity extending toward the inner diameter.

The magnetic recording medium includes a non-magnetic support, a magnetic layer including a ferromagnetic powder on one surface of the non-magnetic support, and a back coating layer including a non-magnetic powder on the other surface of the non-magnetic support, in which a difference (S.sub.after−S.sub.before) between a spacing S.sub.after measured by optical interferometry regarding a surface of the back coating layer after methyl ethyl ketone cleaning and a spacing S.sub.before measured by optical interferometry regarding the surface of the back coating layer before methyl ethyl ketone cleaning is greater than 0 nm and equal to or smaller than 30.0 nm, and the non-magnetic support is an aromatic polyamide support having a moisture absorption of 2.2% or less.

A method, according to one approach, includes forming an underlayer of a magnetic recording medium. The underlayer includes encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an aromatic polymer, and a polymeric binder binding the encapsulated nanoparticles. The underlayer is cured by irradiating the underlayer for causing crosslinking of the polymeric binder. In another approach, a method includes forming an underlayer of a magnetic recording medium by spray coating a mixture of a magnetic nanoparticles, aromatic polymer, and polymeric binder onto a structure as a sprayed-on aerosol coating; and curing the underlayer.

A method, according to one approach, includes forming an underlayer of a magnetic recording medium. The underlayer includes encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an aromatic polymer, and a polymeric binder binding the encapsulated nanoparticles. A method, according to another approach, includes mixing encapsulated nanoparticles with a polymeric binder and a solvent to form a mixture, the encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an aromatic polymer. The mixture is applied onto a structure. The applied mixture is at least partially dried and cured.

A tape cartridge, according to one approach, includes a housing, and a magnetic recording tape at least partially stored in the housing. The magnetic recording tape including a recording layer having encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an encapsulating layer, and a polymeric binder binding the encapsulated nanoparticles. A tape cartridge, according to another approach, includes a housing, and a magnetic recording tape at least partially stored in the housing. The magnetic recording tape include an underlayer having encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an aromatic polymer, and a polymeric binder binding the encapsulated nanoparticles.

To provide a resin film, of which dimensional stability required of an ultra-high density recording medium can be controlled easily by drive tension, and which has processability at high temperature in a processing step of the resin film into a magnetic recording medium. A resin film having a Young's modulus in the film longitudinal direction of 1 GPa or more and a film thickness of 1 μm or more, wherein the product of the Young's modulus in the longitudinal direction and the thickness is 5 GPa.Math.μm or more and 20 GPa.Math.μm or less and wherein a dimensional change in the film longitudinal direction is −2% or more and +2% or less when the film is heated at a rate of 5° C./min under a load of 2 kg/mm.sup.2 applied in the longitudinal direction and the temperature has reached 110° C., the resin film satisfying at least either of the following (1) or (2): (1) the Young's modulus in the film longitudinal direction is 6 GPa or less and the film thickness is 4.5 μm or less; and (2) the Young's modulus in the film longitudinal direction is 4 GPa or less and the film thickness is 6 μm or less.

A tape cartridge, according to one approach, includes a housing, and a magnetic recording tape at least partially stored in the housing. The magnetic recording tape including a recording layer having encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an encapsulating layer, and a polymeric binder binding the encapsulated nanoparticles. A tape cartridge, according to another approach, includes a housing, and a magnetic recording tape at least partially stored in the housing. The magnetic recording tape include an underlayer having encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an aromatic polymer, and a polymeric binder binding the encapsulated nanoparticles.