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.

Provided is a magnetic recording medium configured to achieve higher density recording. The magnetic recording medium has a tape-like shape, and includes: a base containing polyester as a main constituent; and a magnetic layer provided on the base, including a plurality of magnetic powders, and configured to record a data signal. An average thickness of the magnetic recording medium is 5.6 μm or less. An average thickness of the base is 4.2 μm or less. An average thickness of the magnetic layer is 90 nm or less. An average aspect ratio of the magnetic powders is 1.0 or greater and 3.0 or less. A coercivity in a perpendicular direction is 3000 oersted or less. A rate of a coercivity in a longitudinal direction to the coercivity in the perpendicular direction is 0.8 or less. The magnetic layer includes a lubricant. An entire BET specific surface area of the magnetic recording medium from which the lubricant has been removed is 2.5 m.sup.2/g or greater.

Provided is a magnetic recording medium configured to achieve higher density recording. The magnetic recording medium has a tape-like shape, and includes: a base containing polyester as a main constituent; and a magnetic layer provided on the base, including a plurality of magnetic powders, and configured to record a data signal. An average thickness of the magnetic recording medium is 5.6 μm or less. An average thickness of the base is 4.2 μm or less. An average thickness of the magnetic layer is 90 nm or less. An average aspect ratio of the magnetic powders is 1.0 or greater and 3.0 or less. A coercivity in a perpendicular direction is 3000 oersted or less. A rate of a coercivity in a longitudinal direction to the coercivity in the perpendicular direction is 0.8 or less. The magnetic layer includes a lubricant. An entire BET specific surface area of the magnetic recording medium from which the lubricant has been removed is 2.5 m.sup.2/g or greater.

A lubricant for a magnetic recording medium capable of forming a lubricant layer having excellent adhesion to a protective layer is provided. A lubricant for a magnetic recording medium contains a fluorine-containing ether compound in which a group having an ethylenic carbon-carbon double bond is disposed at one or both terminals of a perfluoroalkyl polyether chain. It is preferable that the group having the ethylenic carbon-carbon double bond is disposed at one terminal of the perfluoroalkyl polyether chain, and a hydroxyl group is disposed at other terminal. It is preferable that the lubricant for a magnetic recording medium contains a compound in which one or more functional groups selected from a hydroxyl group, an amino group, an amido group and a carboxyl group is disposed at one or both terminals of a perfluoroalkyl polyether chain.

A heat-assisted magnetic recording (HAMR) media that has a substrate, a granular magnetic recording layer on the substrate, a carbon overcoat, and a non-magnetic seed layer between the granular magnetic recording layer and the carbon overcoat. The seed layer has a refractive index (n) of no more than 0.5 and an extinction coefficient (k) of at least 1, and a thickness no greater than 10 Angstrom. The seed layer can be at least one of Ag, Au, and Cu.

There is provided a fluorine-containing ether compound represented by the following formula. R.sup.1—R.sup.2—CH.sub.2—R.sup.3—CH.sub.2—OCH.sub.2CH(OH)CH.sub.2O—CH.sub.2—R.sup.3—CH.sub.2—R.sup.4—R.sup.5 (in the formula. R.sup.3 represents a perfluoropolyether chain; R.sup.2 and R.sup.4 represent a divalent linking group having a polar group; R.sup.1 and R.sup.5 represent a terminal group bonded to an oxygen atom of R.sup.2 or R.sup.4; and at least one of R.sup.1 and R.sup.5 is any one selected from the group consisting of an alkenyl group having 2 to 8 carbon atoms, an alkynyl group having 3 to 8 carbon atoms, an aromatic hydrocarbon-containing group, and an aromatic heterocycle-containing group).

Various apparatuses, systems, methods, and media are disclosed to provide a magnetic recording medium that capping layer doped with an effective amount of metal to control grain-to-grain exchange coupling in a capping layer. A magnetic recording medium includes a substrate, a magnetic recording layer (MRL) on the substrate, and a capping layer on the MRL. The capping layer include Co and is doped with a metal (e.g., Ru or Ta) in a range from 1 atomic percent to 5 atomic percent, inclusive.

There is provided a fluorine-containing ether compound represented by the following formula. R.sup.1—R.sup.2—CH.sub.2—R.sup.3—CH.sub.2—OCH.sub.2CH(OH)CH.sub.2O—CH.sub.2—R.sup.3—CH.sub.2—R.sup.4—R.sup.5 (in the formula, R.sup.3 represents a perfluoropolyether chain; R.sup.2 and R.sup.4 represent a divalent linking group having a polar group and may be the same or different from each other; R.sup.1 and R.sup.5 represent a terminal group bonded to an oxygen atom of R.sup.2 or R.sup.4 and may be the same or different from each other; and at least one of R.sup.1 and R.sup.5 is an organic group having 1 to 8 carbon atoms and at least one of hydrogens included in the organic group is substituted by a cyano group).

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##

Provided is a glass for a magnetic recording medium substrate or for a glass spacer for a magnetic recording/reproducing apparatus, in which the total content of Li.sub.2O, Na.sub.2O, K.sub.2O, B.sub.2O.sub.3, and ZnO (Li.sub.2O+Na.sub.2O+K.sub.2O+B.sub.2O.sub.3+ZnO) is in a range of 0 mol % or more and 3 mol % or less, the mole ratio of the total content of Al.sub.2O.sub.3 and MgO relative to the total content of SiO.sub.2 and CaO [(Al.sub.2O.sub.3+MgO)/(SiO.sub.2+CaO)] is in a range of 0.30 or more and 0.6 or less, the total content of SiO.sub.2 and Al.sub.2O.sub.3 (SiO.sub.2+Al.sub.2O.sub.3) is in a range of 64 mol % or more and 85 mol % or less, and the total content of SiO.sub.2, Al.sub.2O.sub.3, MgO, and CaO (SiO.sub.2+Al.sub.2O.sub.3+MgO+CaO) is in a range of 87 mol % or more and 98 mol % or less.