A method for producing a magnetic powder includes performing a reduction treatment on the surface of particles including a hard magnetic material to form core-shell particles each having a shell portion including a soft magnetic material.

A method for producing a magnetic powder includes performing a reduction treatment on the surface of particles including a hard magnetic material to form core-shell particles each having a shell portion including a soft magnetic material.

The magnetic tape includes: a non-magnetic support; a magnetic layer that includes ferromagnetic powder on one surface side of the non-magnetic support; and a back coating layer that includes non-magnetic powder on the other surface side of the non-magnetic support, in which the ferromagnetic powder is ferromagnetic powder selected from the group consisting of hexagonal strontium ferrite powder and ε-iron oxide powder, and the number of protrusions having a height of 50 nm or more and less than 75 nm on a surface of the back coating layer is 700 pieces/6400 μm.sup.2 or less.

The magnetic tape includes: a non-magnetic support; a magnetic layer that includes ferromagnetic powder on one surface side of the non-magnetic support; and a back coating layer that includes non-magnetic powder on the other surface side of the non-magnetic support, in which the ferromagnetic powder is ferromagnetic powder selected from the group consisting of hexagonal strontium ferrite powder and ε-iron oxide powder, and the number of protrusions having a height of 50 nm or more and less than 75 nm on a surface of the back coating layer is 700 pieces/6400 μm.sup.2 or less.

The invention provides a core-shell particle which can provide, by being calcinated, epsilon type iron oxide-based compound particles that have a small coefficient of variation of primary particle diameter and show excellent SNR and running durability when employed in a magnetic recording medium as well as applications thereof. The core-shell particle includes: a core including at least one iron oxide selected from Fe.sub.2O.sub.3 or Fe.sub.3O.sub.4, or iron oxyhydroxide; and a shell that coats the core, the shell including a polycondensate of a metal alkoxide and a metal element other than iron, as well as applications thereof.

The invention provides a core-shell particle which can provide, by being calcinated, epsilon type iron oxide-based compound particles that have a small coefficient of variation of primary particle diameter and show excellent SNR and running durability when employed in a magnetic recording medium as well as applications thereof. The core-shell particle includes: a core including at least one iron oxide selected from Fe.sub.2O.sub.3 or Fe.sub.3O.sub.4, or iron oxyhydroxide; and a shell that coats the core, the shell including a polycondensate of a metal alkoxide and a metal element other than iron, as well as applications thereof.

[Object] To provide technologies such as an orientation device capable of increasing strength of a magnetic field in a transport path. [Solving Means] An orientation device according to the present technology includes a transport path, a permanent magnet portion, and a yoke portion. The transport path allows a base on which a magnetic coating film containing magnetic powder has been formed to pass through the transport path along a transport direction. The permanent magnet portion includes a plurality of first permanent magnets, and a plurality of second permanent magnets that is opposed to the plurality of first permanent magnets across the transport path in a vertical direction that is vertical to the transport direction in a manner that opposite poles face each other, the permanent magnet portion vertically orienting particles of the magnetic powder by applying a magnetic field to the magnetic coating film on the base that passes through the transport path. The yoke portion is made of a soft magnetic material, and connects to poles on a side opposite to the transport path side of the plurality of first permanent magnets, and to poles on a side opposite to the transport path side of the plurality of second permanent magnets.

[Object] To provide technologies such as an orientation device capable of increasing strength of a magnetic field in a transport path. [Solving Means] An orientation device according to the present technology includes a transport path, a permanent magnet portion, and a yoke portion. The transport path allows a base on which a magnetic coating film containing magnetic powder has been formed to pass through the transport path along a transport direction. The permanent magnet portion includes a plurality of first permanent magnets, and a plurality of second permanent magnets that is opposed to the plurality of first permanent magnets across the transport path in a vertical direction that is vertical to the transport direction in a manner that opposite poles face each other, the permanent magnet portion vertically orienting particles of the magnetic powder by applying a magnetic field to the magnetic coating film on the base that passes through the transport path. The yoke portion is made of a soft magnetic material, and connects to poles on a side opposite to the transport path side of the plurality of first permanent magnets, and to poles on a side opposite to the transport path side of the plurality of second permanent magnets.

The magnetic tape includes a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which the magnetic layer includes one or more components selected from the group consisting of fatty acid and fatty acid amide, 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 on a surface of the magnetic layer at a photoelectron take-off angle of 10 degrees is equal to or greater than 45 atom %, and an absolute value ΔN of a difference between a refractive index Nxy measured regarding an in-plane direction of the magnetic layer and a refractive index Nz measured regarding a thickness direction of the magnetic layer is 0.25 to 0.40.

The magnetic tape includes a non-magnetic support; and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, in which the magnetic layer includes one or more components selected from the group consisting of fatty acid and fatty acid amide, 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 on a surface of the magnetic layer at a photoelectron take-off angle of 10 degrees is equal to or greater than 45 atom %, and an absolute value ΔN of a difference between a refractive index Nxy measured regarding an in-plane direction of the magnetic layer and a refractive index Nz measured regarding a thickness direction of the magnetic layer is 0.25 to 0.40.