[Solving Means] A method of producing a magnetic powder includes: coating a surface of each of silica-coated precursor particles with at least one type of coating agent of a metal chloride or a sulfate; and firing the precursor particles coated with the coating agent.

A method, according to one approach, includes forming an underlayer of a magnetic recording medium. The underlayer includes encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an aromatic polymer, and a polymeric binder binding the encapsulated nanoparticles. The underlayer is cured by irradiating the underlayer for causing crosslinking of the polymeric binder. In another approach, a method includes forming an underlayer of a magnetic recording medium by spray coating a mixture of a magnetic nanoparticles, aromatic polymer, and polymeric binder onto a structure as a sprayed-on aerosol coating; and curing the underlayer.

Provided are a magnetic tape including: a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which a total thickness of the magnetic tape is equal to or smaller than 5.30 μm, the magnetic layer has a servo pattern, a center line average surface roughness Ra measured on a surface of the magnetic layer is equal to or smaller than 1.8 nm, and an absolute value ΔN of a difference between a refractive index Nxy of the magnetic layer, measured in an in-plane direction and a refractive index Nz of the magnetic layer, measured in a thickness direction is 0.25 to 0.40, a magnetic tape cartridge and a magnetic tape apparatus including this magnetic tape, a magnetic tape cartridge and a magnetic tape apparatus including this magnetic tape.

Provided are a magnetic tape including: a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which a total thickness of the magnetic tape is equal to or smaller than 5.30 μm, the magnetic layer has a servo pattern, a center line average surface roughness Ra measured on a surface of the magnetic layer is equal to or smaller than 1.8 nm, and an absolute value ΔN of a difference between a refractive index Nxy of the magnetic layer, measured in an in-plane direction and a refractive index Nz of the magnetic layer, measured in a thickness direction is 0.25 to 0.40, a magnetic tape cartridge and a magnetic tape apparatus including this magnetic tape, a magnetic tape cartridge and a magnetic tape apparatus including this magnetic tape.

A method, according to one approach, includes forming an underlayer of a magnetic recording medium. The underlayer includes encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an aromatic polymer, and a polymeric binder binding the encapsulated nanoparticles. A method, according to another approach, includes mixing encapsulated nanoparticles with a polymeric binder and a solvent to form a mixture, the encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an aromatic polymer. The mixture is applied onto a structure. The applied mixture is at least partially dried and cured.

Provided is a sputtering target, the sputtering target containing 0.05 at % or more of Bi and having a total content of metal oxides of from 10 vol % to 60 vol %, the balance containing at least Co and Pt.

There is provided an oriented body containing platinum group-substituted-6 iron oxide particles typified by Rh-substituted ε-iron oxide or Ru-substituted ε-iron oxide applicable to MAMR, MIMR, or F-MIMR system, and a technique related thereto, containing platinum group element-substituted ε-iron oxide particles in which a part of ε-iron oxide is substituted with at least one element of platinum group elements, as magnetic particles wherein the degree of orientation of the magnetic particles defined by the degree of orientation=SQ (direction of magnetization easy-axes)/SQ (direction of magnetization hard-axes) exceeds 5.0, and a coercive force exceeds 31 kOe.

Provided are a magnetic tape including: a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which a total thickness of the magnetic tape is equal to or smaller than 5.30 μm, the magnetic layer has a servo pattern, a center line average surface roughness Ra measured on a surface of the magnetic layer is equal to or smaller than 1.8 nm, and an absolute value ΔN of a difference between a refractive index Nxy of the magnetic layer, measured in an in-plane direction and a refractive index Nz of the magnetic layer, measured in a thickness direction is 0.25 to 0.40, a magnetic tape cartridge and a magnetic tape apparatus including this magnetic tape, a magnetic tape cartridge and a magnetic tape apparatus including this magnetic tape.

A magnetic recording medium is used in a recording/reproduction apparatus having a shortest recording wavelength of not more than 75 nm, the magnetic recording medium including a recording layer that contains a powder of particles containing ε-iron oxide, in which a squareness ratio measured in a traveling direction of the magnetic recording medium is not more than 30%, a ratio (D.sub.max/D.sub.min) of an average longest diameter D.sub.max of the particles to an average shortest diameter D.sub.min of the particles satisfies a relationship of 1.0≤(D.sub.max/D.sub.min)≤1.1, an average thickness δ.sub.mag of the recording layer is not more than 100 nm, and a ratio (δ.sub.mag/D.sub.min) of the average thickness δ.sub.mag of the recording layer to the average shortest diameter D.sub.min of the particles satisfies a relationship of δ.sub.mag/D.sub.min≤5.

A method, according to one approach, includes forming an underlayer of a magnetic recording medium. The underlayer includes encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an aromatic polymer, and a polymeric binder binding the encapsulated nanoparticles. A method, according to another approach, includes mixing encapsulated nanoparticles with a polymeric binder and a solvent to form a mixture, the encapsulated nanoparticles each comprising a magnetic nanoparticle encapsulated by an aromatic polymer. The mixture is applied onto a structure. The applied mixture is at least partially dried and cured.