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 invention provides a magnetic recording medium including a magnetic layer or a magnetic recording layer having a granular structure in which magnetic crystal grains are well separated from each other. The magnetic recording medium includes a substrate, a seed layer, and a magnetic recording layer, wherein the magnetic recording layer includes a first magnetic layer which is a continuous film consisting of an ordered alloy, and a second magnetic layer having a granular structure consisting of magnetic crystal grains consisting of an ordered alloy and a non-magnetic crystal grain boundary, and the seed layer consists of a material selected from the group consisting of an NaCl-type compound, a spinel-type compound, and a perovskite-type compound.

The present invention relates to a magnetic recording medium, and this magnetic recording medium includes at least a non-magnetic substrate and a magnetic recording layer. In the magnetic recording medium of the present invention, the magnetic recording layer includes an ordered alloy having an L1.sub.0-ordered structure, includes Fe, Pt, and V, and has a composition of Pt>Fe. The magnetic recording layer preferably has a granular structure composed of magnetic crystal grains including the ordered alloy and a non-magnetic crystal grain boundary, and the non-magnetic crystal grain boundary includes

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 recording medium includes: a non-magnetic support; a magnetic layer containing a ferromagnetic powder; and a non-magnetic layer containing a non-magnetic powder between the non-magnetic support and the magnetic layer, in which a total chlorine content of the magnetic layer and the non-magnetic layer is 30.0 mg/m.sup.2 or less as a value per unit area, and a total iron content of the magnetic layer and the non-magnetic layer is 300.0 mg/m.sup.2 or less as a value per unit area.

Provided is a magnetic tape, in which, in an environment of a temperature of 32 C. and a relative humidity of 80%, a frictional force F.sub.45 on a magnetic layer surface with respect to an LTO8 head measured at a head tilt angle of 45 is 4 gf or more and 15 gf or less, and standard deviation of a frictional force F on the magnetic layer surface with respect to the LTO8 head measured at each of head tilt angles of 0, 15, 30, and 45 is 10 gf or less. A magnetic tape cartridge and a magnetic tape apparatus include the magnetic tape.