An aspect of the present invention relates to a magnetic recording medium, which comprises a nonmagnetic layer comprising nonmagnetic powder and binder on a nonmagnetic support, and a magnetic layer comprising ferromagnetic powder and binder on the nonmagnetic layer, wherein the magnetic layer further comprises carbon black, and a state in which the carbon black is present, as observed in a reflection electron image of a surface of the magnetic layer obtained by a scanning electron microscope, satisfies condition 1 and condition 2 below: condition 1: a number of carbon black particles with a particle size of greater than or equal to 140 nm is greater than or equal to 30 per 1,000 m.sup.2 of area; and condition 2: a number of carbon black particles with a particle size of greater than or equal to 220 nm is less than or equal to 10 per 1,000 m.sup.2 of area.

The magnetic tape device includes a magnetic tape; and a reproducing head, in which the reproducing head is a TMR head, a center line average surface roughness Ra measured regarding a surface of the magnetic layer of the magnetic tape is equal to or smaller than 2.0 nm, a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, and a ratio (Sdc/Sac) of an average area Sdc of a magnetic cluster of the magnetic tape in a DC demagnetization state and an average area Sac of a magnetic cluster of the magnetic tape in an AC demagnetization state measured with a magnetic force microscope is 0.80 to 1.30.

The magnetic tape device includes a TMR head as a reproducing head; and a magnetic tape which includes a non-magnetic support, and a magnetic layer including ferromagnetic hexagonal ferrite powder and a binding agent on the non-magnetic support, an XRD intensity ratio (Int(110)/Int(114)) of a hexagonal ferrite crystal structure obtained by an X-ray diffraction analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical direction squareness ratio of the magnetic tape is 0.65 to 1.00, a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 2.0 nm, and a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050.

The magnetic tape includes a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which a center line average surface roughness Ra measured regarding the surface of the magnetic layer is equal to or smaller than 1.8 nm, a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, the ferromagnetic powder is ferromagnetic hexagonal ferrite powder, the magnetic layer includes an abrasive, and a tilt cos of the ferromagnetic hexagonal ferrite powder with respect to a surface of the magnetic layer acquired by cross section observation performed by using a scanning transmission electron microscope is 0.85 to 1.00.

The magnetic tape includes a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which a center line average surface roughness Ra measured regarding a surface of the magnetic layer is equal to or smaller than 1.8 nm, a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, and a contact angle with respect to 1-bromonaphthalene measured regarding the surface of the magnetic layer is 45.0 to 55.0.

The magnetic recording medium has a magnetic layer containing ferromagnetic powder and binder on a nonmagnetic support, wherein the ferromagnetic powder is hexagonal ferrite powder containing, based on number of particles, greater than or equal to 80% isotropic particles that satisfy the relation 1: major axis length/minor axis length <1.2, with an average particle size of the hexagonal ferrite powder being less than or equal to 30 nm, and a squareness in a vertical direction of the magnetic layer being greater than or equal to 0.65 but less than or equal to 1.00.

The magnetic recording medium comprises a magnetic layer comprising ferromagnetic powder and binder on a nonmagnetic support, and further comprises a compound denoted by Formula (1): ##STR00001##
wherein, in Formula (1), X denotes O, S, or NR.sup.1; each of R and R.sup.1 independently denotes a hydrogen atom or a monovalent substituent; L denotes a divalent connecting group; Z denotes a partial structure of valence n comprising at least one group selected from the group consisting of carboxyl groups and carboxylate groups; m denotes an integer of greater than or equal to 2, and n denotes an integer of greater than or equal to 1.

The magnetic recording medium composition contains ferromagnetic powder, binder, and a crosslinkable component selected from the group consisting of a component capable of forming a crosslinking structure by a radical reaction, a component capable of forming a crosslinking structure by an ionic reaction, and a component capable of forming a crosslinking structure by a pericyclic reaction, wherein the crosslinkable component contains at least polyester, and the polyester has a weight average molecular weight ranging from 1,000 to 20,000, as well as contains, per molecule, one or more acidic groups, and one or more reactive groups selected from the group consisting of a radical reactive group, an ionic reactive group, and a pericyclic reactive group.

The magnetic tape includes a magnetic layer containing ferromagnetic hexagonal ferrite powder, abrasive, and binder on a nonmagnetic support, wherein the ferromagnetic hexagonal ferrite powder exhibits an activation volume of less than or equal to 1,800 nm.sup.3, and inclination, cos , of the ferromagnetic hexagonal ferrite powder relative to a surface of the magnetic layer as determined by sectional observation by a scanning electron transmission microscope is greater than or equal to 0.85 but less than or equal to 1.00.

A heat-assisted magnetic recording (HAMR) medium includes a substrate, a bi-layer, a heat-sink layer, and a magnetic-recording layer. The bi-layer includes a seed layer disposed on the substrate, and a thermal-transport-control layer (TTCL) disposed on seed layer. The heat-sink layer is disposed on the TTCL; and the magnetic-recording layer is disposed on the heat-sink layer. The bi-layer is configured to enable use of a 50% thinner heat-sink layer that allows use of a reduced operating current of a laser in HAMR write operations while maintaining about the same write performance parameters as a HAMR medium that includes a thermal-barrier layer (TBL) and twice as thick heat-sink layer. 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.