Abstract: A perpendicular magnetic recording medium has a magnetic recording layer consisting of two layers. The first magnetic layer, which is a lower layer, comprises crystal grains of a ferromagnetic Co—Cr alloy system and nonmagnetic grain boundaries mainly composed of oxide or nitride, and a thickness a of the first magnetic layer is from 10 nm to 30 nm. The second magnetic layer, which is an upper layer, comprises an amorphous alloy film composed of rare earth element—transition metal alloy, and a thickness b of the second magnetic layer is from 2 nm to 15 nm. The ratio a/b of the thickness a of the first magnetic layer and the thickness b of the second magnetic layer is at least two.

Abstract: A magnetic recording medium exhibits a high coercive force and suppresses noises caused therefrom at a low level. The magnetic recording medium includes a nonmagnetic substrate, a nonmagnetic undercoating layer on the substrate where the undercoating layer has a hexagonal close packing structure or a combination of the hexagonal close packing structure and a body center cubic structure. The magnetic recording medium includes a nonmagnetic intermediate layer on the undercoating layer, where the intermediate layer has a hexagonal close packing structure or a combination of the hexagonal close packing structure and a body center cubic structure, and a magnetic layer on the intermediate layer. The magnetic layer has a granular structure formed of ferromagnetic crystal grains and oxide grain boundaries or nitride grain boundaries surrounding the ferromagnetic crystal grains.

Abstract: A magnetic recording medium has a non-magnetic under-layer, a magnetic layer, a protective film and a liquid lubricant layer sequentially laminated on a non-magnetic substrate. The magnetic layer has a multi-layer structure laminated with two or more magnetic layer components, each of the magnetic layer components having ferromagnetic grains and non-magnetic grain boundaries surrounding the grain. The resulting magnetic recording medium has a granular magnetic layer exhibiting very high Hc accompanying high density of magnetic recording, while decreasing the amount of platinum needed for attaining the high Hc, and reducing media noise accompanying the high recording density.

Abstract: A magnetic recording medium has at least a non-magnetic under-layer, a magnetic layer, a protective layer and a liquid lubricant layer sequentially laminated on a non-magnetic substrate. The magnetic layer includes ferromagnetic grains and non-magnetic grain boundaries formed of metallic oxide or carbide surrounding the ferromagnetic grains. A non-magnetic intermediate layer, having grains of non-magnetic substance and non-magnetic grain boundaries, formed of metallic oxide or carbide, surrounding the grains of non-magnetic substance, is provided between the non-magnetic under-layer and the magnetic layer. The resulting magnetic recording medium exhibits a high coercive force, Hc, and low noise. Furthermore, the resulting magnetic recording medium prevents the deterioration of the media characteristics in an initial growth region in the granular magnetic layer.

Abstract: In a magnetic recording medium, a plurality of non-magnetic metallic intermediate layers is laminated between an under-layer and a magnetic layer. One of the intermediate layers is composed of at least an element selected from the group consisting of Ru, Re and Os and contains oxygen, and another is composed of a CoCr alloy containing at least an element selected from the group consisting of Nb, Mo, Ru, Rh, Pd, Ta, W, Re Os, Ir and Pt. The resulting magnetic recording medium provides reduced costs and improved recording characteristics.

Abstract: A magnetic recording medium achieves excellent noise reduction by controlling the crystal orientation of a magnetic layer without thermal processing. The magnetic recording medium includes multiple layers laminated to a substrate. These layers include at least the magnetic layer and a non-magnetic under layer. The magnetic layer has a granular structure consisting of ferromagnetic grains with a hexagonal close-packed structure and non-magnetic grain boundaries composed mainly oxide or a nitride. The non-magnetic under-layer is a material having a body centered cubic crystal structure with a preferential orientation along a (200) plane parallel to a film surface of the under-layer.

Abstract: A manufacturing method achieves excellent magnetic recording characteristics by sequentially sputtering a non-magnetic under-layer, a non-magnetic intermediate layer, and a magnetic layer on a non-magnetic substrate in an atmosphere of H2O partial pressure of 2×10−10 Torr or lower. This process allows beneficial deposition of the magnetic layer and reduces raw materials costs. The magnetic layer includes ferromagnetic grains and non-magnetic grain boundaries. The intermediate layer has a hexagonal close-packed crystal structure. The manufacturing method allows manufacture of a high quality magnetic recording medium without a heating step thereby allowing use of lower cost materials, reduces manufacturing time, and increases savings.

Abstract: The present invention provides a sputtering target for production of a magnetic recording medium including at least a nonmagnetic undercoat layer, a magnetic layer, and a protective layer laminated sequentially on a nonmagnetic substrate, the sputtering target being used for film formation of the magnetic layer, the sputtering target comprising a mixture of a metal and an oxide, and the particle diameter of the oxide in the sputtering target being 10 &mgr;m or less. The sputtering target suppresses abnormal discharge occurring during film formation of a granular magnetic layer of the magnetic recording medium, and suppresses occurrence of foreign objects on the magnetic recording medium.

Abstract: The present invention provides a magnetic recording medium including at least a nonmagnetic undercoat layer, a nonmagnetic metallic intermediate layer, a magnetic layer, a protective film, and a liquid lubricant layer sequentially laminated on a nonmagnetic substrate, wherein the magnetic layer contains crystal grains having ferromagnetism and nonmagnetic grain boundaries surrounding the crystal grains, and the nonmagnetic metallic intermediate layer contains at least one layer, and the crystal structure of each layer being a hexagonal close-packed structure; and a method for producing the magnetic recording medium. The magnetic recording medium shows high coercive force Hc and a low medium noise, and its manufacturing cost is also low.

Abstract: A magnetic recording medium according to the invention includes a plastic substrate, a non-magnetic under-layer on the substrate, a magnetic layer including cobalt on the under-layer, a protective film on the magnetic layer, and a liquid lubricant layer on the protective film. The under-layer is composed of a chromium alloy having a body centered cubic lattice structure, and containing at least one element selected from the group consisting of Zr, Nb, Mo, Ru and Pd in a total amount of at least 15 at %, or containing at least one element selected from the group consisting of Hf, Ta, W, Re, Pt and Au in a total amount of at least 10 at %. The amount of cobalt dissolved out of the magnetic layer is limited by performing sputtering deposition of at least the magnetic layer at low pressures of argon.