A magnetic recording medium substrate is provided in which a NiP type plating film is formed on a surface of an aluminum alloy substrate that includes Si in a range of 9.5 mass % or more and 11.0 mass % or less, Mn in a rage of 0.45 mass % or more and 0.90 mass % or less, Zn in a range of 0.32 mass % or more and 0.38 mass % or less, Sr in a range of 0.01 mass % or more and 0.05 mass % or less. In the alloy structure of the aluminum alloy substrate, an average particle diameter of Si particles is 2 μm or less, the film thickness of the NiP type plating film is 7 μm or more. An outer diameter of the magnetic recording medium substrate is 53 mm or more, the thickness is 0.9 mm or less, and the Young's modulus is 79 GPa or more.

Provided are a magnetic recording heading having a magnetic film including a write gap, in which in the write gap, a recording surface-side gap width is narrower than a back surface-side gap width, and the write gap has an opening portion formed by ion beam processing at a gap end portion on a recording surface side, a magnetic recording apparatus including the magnetic recording head, a manufacturing method of the magnetic recording head, and a manufacturing method of a magnetic recording medium having a servo pattern, including forming a servo pattern on the magnetic recording medium by the magnetic recording head.

Provided is a magnetic recording medium having a large magnetocrystalline anisotropy constant K.sub.u and a high coercivity H.sub.c as well as a sputtering target used for producing such a magnetic recording medium.

A Pt-oxide-based sputtering target consists of 60 vol % or more and less than 100 vol % of a Pt-base alloy phase and more than 0 vol % and 40 vol % or less of an oxide, where the Pt-base alloy phase contains 50 at % or more and 100 at % or less of Pt.

Provided is a magnetic tape in which a center line average surface roughness Ra measured regarding a surface of a magnetic layer is equal to or smaller than 1.8 nm, logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding the surface of the magnetic layer is equal to or smaller than 0.050, a back coating layer includes one or more components selected from the group consisting of fatty acid and fatty acid amide, and a C—H derived C concentration calculated from a C—H peak area ratio of C1s spectra obtained by X-ray photoelectron spectroscopic analysis performed regarding a surface of the back coating layer at a photoelectron take-off angle of 10 degrees is equal to or greater than 35 atom %.

According to one embodiment, a magnetic recording and reproducing device includes a magnetic recording medium, and a magnetic head including a first reproducing unit. The first reproducing unit includes a first magnetic field generator separated from the magnetic recording medium in a first direction, and a first stacked body. At least a portion of the first stacked body is provided between the magnetic recording medium and the first magnetic field generator in the first direction. The first stacked body includes a first magnetic layer, a second magnetic layer separated from the first magnetic layer in a second direction crossing the first direction, and a first intermediate layer provided between the first magnetic layer and the second magnetic layer. The first stacked body performs an operation of generating a first alternating magnetic field. The first magnetic field generator generates a first magnetic field.

A biaxially orientated polyester film has a P.sub.L/V.sub.L ratio of 0.3 to 1.2, P.sub.L and V.sub.L representing the average diameter of the convex portions and the average diameter of the concave portions, respectively, that are defined on the basis of a slice level with a height of 0 nm (reference plane) in a roughness curve determined for at least one surface using a three dimensional surface roughness meter, and the convex portions accounting for an area ratio of 30% to 51% of the reference plane. The biaxially oriented polyester film is excellent in travelling property, slitting property, and dimensional stability, and serves, when used for magnetic recording medium production, to provide a high density magnetic recording medium having a smooth magnetic layer, suffering little dimensional change due to variations in environmental parameters such as temperature and humidity or due to storage, and having good electromagnetic conversion characteristics with little dropout.

A magnetic recording medium includes: a substrate; and a magnetic layer including a ferrimagnetic particle powder. A product (V×SFD) of a particle volume V and a holding force distribution SFD of the ferrimagnetic particle is equal to or less than 2500 nm3.

A magnetic recording medium includes: a substrate; and a magnetic layer including a ferrimagnetic particle powder. A product (V×SFD) of a particle volume V and a holding force distribution SFD of the ferrimagnetic particle is equal to or less than 2500 nm3.

A three-dimensional magnetic recording media can consist of a single recording layer configured with three or more separate magnetization levels. A first magnetization level can be written to a selected region of said recording layer by applying a first write field to the grains of said region to form a “spin-up” magnetization in the grains of said region. A second magnetization level can be written by applying a second opposite write field to selected grains of said region to form a “spin-down” magnetization. At least a third intermediate magnetization level can be written by applying a weaker or alternating write field to grains of said region to form an intermediate magnetization comprising a mixture of spin-up and spin-down grains. By such method, said region may comprise a data bit capable of storing 3 or more units of information corresponding to the number of separate magnetization levels employed.

A three-dimensional magnetic recording media can consist of a single recording layer configured with three or more separate magnetization levels. A first magnetization level can be written to a selected region of said recording layer by applying a first write field to the grains of said region to form a “spin-up” magnetization in the grains of said region. A second magnetization level can be written by applying a second opposite write field to selected grains of said region to form a “spin-down” magnetization. At least a third intermediate magnetization level can be written by applying a weaker or alternating write field to grains of said region to form an intermediate magnetization comprising a mixture of spin-up and spin-down grains. By such method, said region may comprise a data bit capable of storing 3 or more units of information corresponding to the number of separate magnetization levels employed.