An apparatus is disclosed. The apparatus includes a storage layer, a first write layer, and a second write layer. The first write layer is disposed over the storage layer. The second write layer is disposed over the first write layer. The anisotropy field and magnetization associated with the second write layer at writing temperature is greater than anisotropy field and magnetization associated with the first write layer at the writing temperature.

A magnetic recording medium has a recording surface having an average surface roughness SRa of 3.0 ?m or less, the number of projections having a height of 7.5 nm or more included in a unit region (where the unit region is a square region with each side having a length of 30 ?m) of the recording surface is 256 or more, and the number of projections having a height of 15 nm or more included in the unit region of the recording surface is 0 or more and 104 or less.

The magnetic tape includes a non-magnetic support, and a magnetic layer containing a ferromagnetic powder. A magnetic tape cartridge and a magnetic tape apparatus include the magnetic tape. VIVA 0.1, which is a height that is obtained by measuring a surface of the magnetic layer with an atomic force microscope and at which a cross-sectional area is 0.1% with a measurement region area as 100%, is 5 nm or more and 10 nm or less, and standard deviation of the VIVA 0.1 in a width direction of the surface of the magnetic layer is 1.0 nm or less.

The magnetic tape includes a non-magnetic support, and a magnetic layer containing a ferromagnetic powder. A magnetic tape cartridge and a magnetic tape apparatus include the magnetic tape. CS VIVA 0.1, which is a height that is obtained by measuring a surface of the magnetic layer with an atomic force microscope and at which a cutout length is 0.1% with a length of one side of a measurement region as 100%, is 4 nm or more and 10 nm or less, and standard deviation a of the CS VIVA 0.1 in a width direction of the surface of the magnetic layer is 1.0 nm or less.

The magnetic tape includes a non-magnetic support, and a magnetic layer containing a ferromagnetic powder. A magnetic tape cartridge and a magnetic tape apparatus include the magnetic tape. Svi obtained by measuring a surface of the magnetic layer with an atomic force microscope and by Equation A is 0.080 or more and 0.130 or less, and standard deviation of the Svi in a width direction of the surface of the magnetic layer is 0.010 or less. In Equation A, Sq is a root-mean-square height Sq specified in ISO 25178, Vv(h.sub.0.8) is a void volume in a region where a load area ratio in a bearing curve is 80% or more and 100% or less, and A is a measurement region area.

[00001]$\begin{array}{cc}\mathrm{Svi}=\left(\frac{\mathrm{Vv}\left(h_{0.8}\right)}{A}\right)/\mathrm{Sq}& \mathrm{Equation}A\end{array}$

The magnetic tape includes a non-magnetic support, and a magnetic layer containing a ferromagnetic powder. A magnetic tape cartridge and a magnetic tape apparatus include the magnetic tape. A core void volume Vvc specified in international organization for standardization (ISO) 25178 on a surface of the magnetic layer is 1.200 nm.sup.3 or more and 3.000 nm.sup.3 or less, and standard deviation a of the Vvc in a width direction of the surface of the magnetic layer is 0.120 nm.sup.3 or less.

Disclosed is a perpendicularly magnetized film structure that uses a highly heat resistant underlayer film on which a cubic or tetragonal perpendicularly magnetized film can grow with high quality, the structure comprising any one substrate (5) of a cubic single crystal substrate having a (001) plane, or a substrate having a cubic oriented film that grows to have the (001) plane; an underlayer (6) formed on the substrate (5) from a thin film of a metal having an hcp structure, such as Ru or Re, in which the [0001] direction of the thin metal film forms an angle in the range of 42 to 54 with respect to the <001> direction or the (001) orientation of the substrate (5); and a perpendicularly magnetized layer (7) located on the metal underlayer (6) and formed from a cubic material selected from the group consisting of a Co-based Heusler alloy, a cobalt-iron (CoFe) alloy having a bcc structure, and the like, as a constituent material, and grown to have the (001) plane.

The magnetic tape includes a non-magnetic support, and a magnetic layer containing a ferromagnetic powder. The ferromagnetic powder is a hexagonal ferrite powder, tilt cos of the hexagonal ferrite powder with respect to a surface of the magnetic layer, which is acquired by cross-sectional observation performed using a scanning transmission electron microscope, is 0.85 or more and 1.00 or less, and standard deviation of the cos in a width direction of the surface of the magnetic layer is 0.03 or less.

There is provided a magnetic recording medium including a surface having a longitudinal direction and a lateral direction. An arithmetic average roughness Ra, a ratio PSD.sub.MD,short/PSD.sub.TD,short, and a ratio PSD.sub.MD,long/PSD.sub.TD,long on the surface satisfy Ra3.0 nm, PSD.sub.MD,short/PSD.sub.TD,short0.65, and 1.3PSD.sub.MD,long/PSD.sub.TD,long2.3, in which PSD.sub.MD,short is an average value of PSD values in a range from 0.15 m to 0.4 m in the longitudinal direction of the surface, PSD.sub.TD,short is an average value of PSD values in a range from 0.15 m to 0.4 m in the lateral direction of the surface, PSD.sub.MD,long is an average value of PSD values in a range from 0.4 m to 5.0 m in the longitudinal direction of the surface, and PSD.sub.TD,long is an average value of PSD values in a range from 0.4 m to 5.0 m in the lateral direction of the surface.

The magnetic tape includes a non-magnetic support, and a magnetic layer containing a ferromagnetic powder. A magnetic tape cartridge and a magnetic tape apparatus include the magnetic tape. A core void volume Vvc specified in international organization for standardization (ISO) 25178 on a surface of the magnetic layer is 1.200 nm.sup.3 or more and 3.000 nm.sup.3 or less, and standard deviation of the Vvc in a width direction of the surface of the magnetic layer is 0.120 nm.sup.3 or less.