Provided is a perpendicular magnetic recording medium that exhibits improved thermal stability and achieves reduction in switching magnetic field by providing a cap layer having characteristics (characteristics contributing to reducing switching magnetic field of the perpendicular magnetic recording medium as well as to improving thermal stability thereof) superior to existing cap layers.

A perpendicular magnetic recording layer (24) has a granular structure which comprises Co- Pt-alloy magnetic crystal grains (24A) and a non-magnetic grain boundary oxide (24B). A cap layer (26) has a granular structure which comprises Co-Pt-alloy magnetic crystal grains (26A) and a magnetic grain boundary oxide (26B). The Co- Pt -alloy magnetic crystal grains (26A) in the cap layer (26) contain 65-90 at % of Co and 10-35 at % of Pt. The magnetic grain boundary oxide (26B) is included in a volume fraction of 5-40 vol % with respect to the total volume of the cap layer (26).

A biaxially oriented polyester film, which exhibits an excellent winding property in a manufacturing process, and realizes an excellent electromagnetic conversion property and less failure of signals of a magnetic recording tape to be produced thereof, is provided. This biaxially oriented polyester film satisfies the formula y≤−24.9X+3.8, where the protrusion height X is 0.075 μm, 0.100 μm, and 0.125 μm, and y denotes a base-10 logarithm value of the number of protrusions having protrusion heights of X or more in a visual field of a region of 282 μm×211 μm, and a protrusion height that corresponds to a 0.4% area of a bearing curve based on protrusion height distribution is 65-90 nm.

A magnetic recording medium includes a substrate, an underlayer provided above the substrate, and a magnetic layer provided on and in contact with the underlayer. The underlayer includes a compound represented by a general formula MgO.sub.(1-x), where x falls within a range of 0.07 to 0.25. The magnetic layer includes an alloy having a L1.sub.0 structure, and the alloy having the L1.sub.0 structure includes one or more elements selected from a group consisting of Al, Si, Ga, and Ge.

A magnetic recording medium includes a substrate, an underlayer disposed above the substrate, and a first magnetic layer disposed above the underlayer. The first magnetic layer has a granular structure including magnetic grains having a L1.sub.0 structure, and grain boundaries. A content of the grain boundaries is in a range of 25 volume percent to 50 volume percent, and the grain boundaries include a chalcogenide-based layered material.

A multilayer exchange spring recording media consists of a magnetically hard magnetic storage layer strongly exchange coupled to a softer nucleation host. The strong exchange coupling can be through a coupling layer or direct. The hard magnetic storage layer has a strong perpendicular anisotropy. The nucleation host consists of one or more ferromagnetic coupled layers. For a multilayer nucleation host the anisotropy increases from layer to layer. The anisotropy in the softest layer of the nucleation host can be two times smaller than that of the hard magnetic storage layer. The lateral exchange between the grains is small. The nucleation host decreases the coercive field significantly while keeping the energy barrier of the hard layer almost unchanged. The coercive field of the total structure depends on one over number of layers in the nucleation host. The invention proposes a recording media that overcomes the writeability problem of perpendicular recording media.

A multilayer exchange spring recording media consists of a magnetically hard magnetic storage layer strongly exchange coupled to a softer nucleation host. The strong exchange coupling can be through a coupling layer or direct. The hard magnetic storage layer has a strong perpendicular anisotropy. The nucleation host consists of one or more ferromagnetic coupled layers. For a multilayer nucleation host the anisotropy increases from layer to layer. The anisotropy in the softest layer of the nucleation host can be two times smaller than that of the hard magnetic storage layer. The lateral exchange between the grains is small. The nucleation host decreases the coercive field significantly while keeping the energy barrier of the hard layer almost unchanged. The coercive field of the total structure depends on one over number of layers in the nucleation host. The invention proposes a recording media that overcomes the writeability problem of perpendicular recording media.

A magnetic recording tape comprises a tape substrate, a perpendicular magnetic recording layer disposed over the tape substrate, and a soft-magnetic underlayer disposed between the recording layer and the tape substrate. The perpendicular magnetic recording layer comprises magnetic particles suspended in a binder material, and the soft-magnetic underlayer comprises a continuous film of soft-magnetic material. The magnetic particles in the recording layer comprise one of barium ferrite, strontium ferrite, epsilon iron oxide and chromium dioxide. Tape storage apparatus employing such tape is also provided. The apparatus comprises a read/write head having at least one probe write-head for writing data by perpendicular recording on magnetic tape, at least one reel of magnetic tape as defined above, and a tape transport mechanism for transporting the magnetic tape past the read/write head.

To provide a magnetic recording medium that has excellent traveling stability in spite of having a thin total thickness and a thin thickness of an underlayer, and is suitable for use in a recording/reproducing device for adjusting the width of the magnetic recording medium by adjusting a tension of the magnetic recording medium in a longitudinal direction thereof. The present technology provides a tape-shaped magnetic recording medium including: a magnetic layer; an underlayer; a base layer; and a back layer, in which the underlayer has a thickness of 0.5 μm or more and 0.9 μm or less, the magnetic recording medium has an average thickness t.sub.T of 5.6 μm or less, the magnetic recording medium includes a lubricant, the magnetic recording medium has pores, and the pores have an average diameter of 6 nm or more and 11 nm or less when the diameters of the pores are measured in a state where the lubricant has been removed from the magnetic recording medium and the magnetic recording medium has been dried, and the Young's modulus in a longitudinal direction is 7.90 GPa or less.

A magnetic recording medium including: a non-magnetic substrate; an underlayer; a perpendicular magnetic layer; a diffusion preventing layer; and a protective layer, wherein the underlayer, the perpendicular magnetic layer, the diffusion preventing layer, and the protective layer are layered on the non-magnetic substrate in this order, the perpendicular magnetic layer has a multi-layer structure, the perpendicular magnetic layer includes an uppermost layer and at least one layer other than the uppermost layer, the uppermost layer including Co or Fe in magnetic particles, and the at least one layer other than the uppermost layer including an oxide, the diffusion preventing layer is provided between the perpendicular magnetic layer and the protective layer, and the diffusion preventing layer includes at least one component selected from a group consisting of Si, Ti, Cr, B, and Ru, or either a carbide, an oxide, or both, of the at least one component.

A heat-assisted magnetic recording (HAMR) medium has a multilayered underlayer between the heat-sink layer and the recording layer. One embodiment of the underlayer is a multilayer of a thermal barrier layer consisting essentially of MgO and TiO, and a seed layer containing MgO and nitrogen (N) directly on the thermal barrier layer, with the recording layer on and in contact with the seed layer. The interface between the thermal barrier layer and the seed layer contains Ti and N, some of which may be present as TiN to act as a diffusion barrier to prevent diffusion of the Ti into the recording layer. The Ti-containing thermal barrier layer has a higher thermal resistivity than the conventional MgO thermal barrier/seed layer and thus allows for reduced laser power to the recording layer while still achieving a high thermal gradient at the recording layer.