Various apparatuses, systems, methods, and media are disclosed to provide a heat-assisted magnetic recording (HAMR) medium that has a media carbon dual-layer media carbon overcoat with both a carbon layer and a carbon-nitrogen (CN) layer. The carbon layer may be a plasma enhanced chemical vapor deposition (PECVD) carbon layer and the CN layer may be a sputtered CN layer. The dual-layer media carbon overcoat helps reduce a laser power requirement of an HAMR disk drive system and thus reduce the operating temperature of a near field transducer (NFT) of a HAMR disk drive. The dual-layer overcoat can also improve thermal and thermo-oxidative stability of the media and help retain a lubricant provided on the overcoat, therefore improving HAMR head-media interface reliability. The dual-layer media carbon overcoat can also reduce carbonaceous smear within a head-media gap.

A magnetic recording medium includes a layer structure including a magnetic layer, a base layer, and a back layer in this order, in which an average thickness t.sub.T is t.sub.T≤5.5 μm, a dimensional variation Δw in a width direction to tension change in a longitudinal direction is 660 ppm/N≤Δw, and a surface roughness R.sub.abe of the base layer on a side of the back layer is 4.2 nm≤R.sub.abe≤8.5 nm.

A fluorine-containing ether compound characterized by being represented by the following formula (1):
R.sup.1—R.sup.2—CH.sub.2—R.sup.3—CH.sub.2—R.sup.4—R.sup.5  (1) In the formula (1), R.sup.3 is a perfluoropolyether chain. R.sup.2 and R.sup.4 are divalent linkage groups having a polar group and may be the same or different. R.sup.1 and R.sup.5 are bonded to an atom other than a carbon atom of R.sup.2 or R.sup.4. R.sup.1 and R.sup.5 are terminal groups composed of an organic group having 1 to 8 carbon atoms and may be the same or different. At least one of R.sup.1 and R.sup.5 is a chain organic group having 1 to 8 carbon atoms wherein one or more hydrogen atoms of the chain organic group is substituted with a group having an amide bond.

Magnetic media including a magnetic recording layer structure formed of alternating magnetic recording sublayers and non-magnetic exchange control sublayers. The magnetic recording layer structure may include at least one magnetic recording sublayer formed to include a pair of thin films, with the films having different concentrations of platinum, ruthenium, and/or oxide segregants. That is, the sublayer has a “dual layer” structure. The dual layer structure can provide a gradient in magnetic anisotropy, saturation magnetization, and/or intergranular magnetic exchange coupling across the sublayer. In some examples, the film nearer to the substrate of the magnetic media has a higher platinum concentration than the other film. In one aspect, the magnetic media includes the substrate and the magnetic recording layer structure on the substrate, with the structure including six magnetic recording sublayers. In another aspect, a method of fabricating magnetic media with such structures is provided.

A magnetic recording medium is provided and includes a magnetic layer, a non-magnetic layer, a base layer and a back layer, wherein an average thickness t.sub.T of the magnetic recording medium is t.sub.T≤5.3 a dimensional change amount Δw in a width direction with respect to a change in tension in a longitudinal direction is 700 ppm/N≤Δw, a thickness of the non-magnetic layer is 2.0 μm or less, a squareness ratio measured in a vertical direction of the magnetic recording medium is 65% or more, and the magnetic layer includes a magnetic powder.

The fluorine-containing ether compound is represented by the following formula (1): R.sup.1—R.sup.2—CH.sub.2—R.sup.3—CH.sub.2—R.sup.4. In the formula (1), R.sup.1 is represented by the following formula (2), R.sup.2 is represented by the following formula (3), R.sup.3 is a perfluoropolyether chain, and R.sup.4 is an organic end group different from R.sup.1—R.sup.2— and contains two or three polar groups, wherein each polar group is bonded to a different carbon atom, and the carbon atoms to which the polar groups are bonded are bonded to one another via a linking group containing a carbon atom to which the polar group is not bonded. In the formula (2), r is 1 to 3. In the formula (3), w is 2 or 3. ##STR00001##

An ionic liquid comprising: a cation (or conjugate acid), wherein the cation (or conjugate acid) is represented by General Formula (A) below or General Formula (B) below or General Formula (C) or General Formula (D) below or General Formula (E) below: ##STR00001## wherein R.sub.1 represents CH.sub.2CH.sub.2(CF.sub.2).sub.nCF.sub.3, where n is an integer ranging from 0 to 7, or an alkyl chain CH.sub.3, or CH.sub.2OH, or CH.sub.2CH.sub.2OH; R.sub.2 represents CH.sub.2CH.sub.2(CF.sub.2).sub.nCF.sub.3, where n is an integer ranging from 0 to 7, or a hydrogen atom H, or CH.sub.2OH, or CH.sub.2CH.sub.2OH; and R.sub.3 represents CH.sub.2CH.sub.2(CF.sub.2).sub.nCF.sub.3, where n is an integer ranging from 0 to 7.

The present invention relates to a magnetic recording medium including a substrate; an underlayer laminated upon the substrate; and a magnetic layer laminated upon the underlayer, wherein the underlayer includes a first underlayer containing a compound represented by a following general formula: MgO.sub.(1-X), where X is within a range of 0.07 to 0.25, the magnetic layer includes a first magnetic layer containing an alloy having a L1.sub.0 structure, and the alloy having the L1.sub.0 structure includes B, and the first underlayer is in contact with the first magnetic layer.

The fluorine-containing ether compound is represented by the following formula (1): R.sup.1—R.sup.2—CH.sub.2—R.sup.3—CH.sub.2—R.sup.4. In the formula (1), R.sup.1 is represented by the following formula (2), R.sup.2 is represented by the following formula (3), R.sup.3 is a perfluoropolyether chain, and R.sup.4 is an organic end group different from R.sup.1—R.sup.2— and contains two or three polar groups, wherein each polar group is bonded to a different carbon atom, and the carbon atoms to which the polar groups are bonded are bonded to one another via a linking group containing a carbon atom to which the polar group is not bonded. In the formula (2), R.sup.5 is an alkoxy group selected from the group consisting of a methoxy, an ethoxy and a propoxy group. In the formula (3), w is 2 or 3.

##STR00001##

The fluorine-containing ether compound is represented by the following formula (1): R.sup.1-R.sup.2—CH.sub.2—R.sup.3—CH.sub.2—R.sup.4. In the formula (1), R.sup.1 is represented by the following formula (2), R.sup.2 is represented by the following formula (3), R.sup.3 is a perfluoropolyether chain, and R.sup.4 is an organic end group different from R.sup.1-R.sup.2- and contains two or three polar groups, wherein each polar group is bonded to a different carbon atom, and the carbon atoms to which the polar groups are bonded are bonded to one another via a linking group containing a carbon atom to which the polar group is not bonded. In the formula (2), r is 1 to 3. In the formula (3), w is 2 or 3.

##STR00001##