Provided is a powder of a -iron oxyhydroxide-based compound that is a group of particles of a 3-iron oxyhydroxide-based compound represented by Formula (1) below; in which a surface of the particles of the -iron oxyhydroxide-based compound is modified with a surface modifier; in which, in a case where the powder is dispersed in water to be made into a sol, a zeta potential of the powder is equal to or higher than +5 mV at pH 10; and

-A.sub.aFe.sub.1-aOOH(1) in which, in Formula (1), A represents at least one metallic element other than Fe, and a represents a number that satisfies a relationship of 0a<1.

Provided is a powder of a -iron oxyhydroxide-based compound that is a group of particles of a 3-iron oxyhydroxide-based compound represented by Formula (1) below; in which a surface of the particles of the -iron oxyhydroxide-based compound is modified with a surface modifier; in which, in a case where the powder is dispersed in water to be made into a sol, a zeta potential of the powder is equal to or higher than +5 mV at pH 10; and

-A.sub.aFe.sub.1-aOOH(1) in which, in Formula (1), A represents at least one metallic element other than Fe, and a represents a number that satisfies a relationship of 0a<1.

A method of encoding information in an object that may allow for enhanced tailorability of the encoding during the processing and/or also enhance the amount of information encoded in the object. More particularly, the method of encoding the object enables the magnetic characteristics at different spatial locations of the object to be modified to form a spatial array of the different magnetic characteristics for representing the encoded information. The method can be used to permanently embed a magnetic signature in a non-magnetic object, for example. More specifically, the method allows different portions of the object to exhibit different magnetic characteristics at each spatial location of the object in three dimensions, and more particularly configuring the magnetic vectors of those portions in many possible orientations with a 4n steradian solid angle and/or with different intensities.

A method of encoding information in an object that may allow for enhanced tailorability of the encoding during the processing and/or also enhance the amount of information encoded in the object. More particularly, the method of encoding the object enables the magnetic characteristics at different spatial locations of the object to be modified to form a spatial array of the different magnetic characteristics for representing the encoded information. The method can be used to permanently embed a magnetic signature in a non-magnetic object, for example. More specifically, the method allows different portions of the object to exhibit different magnetic characteristics at each spatial location of the object in three dimensions, and more particularly configuring the magnetic vectors of those portions in many possible orientations with a 4n steradian solid angle and/or with different intensities.

In a perpendicular magnetic recording medium and a method of manufacturing the same, a first magnetic recording layer includes first magnetic crystal grains and a first non-magnetic portion containing carbon, a second magnetic recording layer includes second magnetic crystal grains and a second non-magnetic portion containing ZnO, a third magnetic recording layer includes third magnetic crystal grains and a third non-magnetic portion containing carbon, a film thickness t2 of the second magnetic recording layer is 0.1 nm to 7.0 nm, a volume fraction x2 of the second non-magnetic portion in the second magnetic recording layer at completion of formation is 0.20 to 0.90, a film thickness t3 of the third magnetic recording layer is 0.5 nm to 4.0 nm, a volume fraction x3 of the third non-magnetic portion in the third magnetic recording layer is 0.20 to 0.70, and (t2/t3)?(x2/x3) is 0.30 to 1.20.

In a perpendicular magnetic recording medium and a method of manufacturing the same, a first magnetic recording layer includes first magnetic crystal grains and a first non-magnetic portion containing carbon, a second magnetic recording layer includes second magnetic crystal grains and a second non-magnetic portion containing ZnO, a third magnetic recording layer includes third magnetic crystal grains and a third non-magnetic portion containing carbon, a film thickness t2 of the second magnetic recording layer is 0.1 nm to 7.0 nm, a volume fraction x2 of the second non-magnetic portion in the second magnetic recording layer at completion of formation is 0.20 to 0.90, a film thickness t3 of the third magnetic recording layer is 0.5 nm to 4.0 nm, a volume fraction x3 of the third non-magnetic portion in the third magnetic recording layer is 0.20 to 0.70, and (t2/t3)?(x2/x3) is 0.30 to 1.20.

Provided are: a magnetic recording medium including a non-magnetic support and a magnetic layer containing a ferromagnetic powder, in which the ferromagnetic powder is an ?-iron oxide powder, a vertical squareness ratio SQ of the magnetic recording medium is 0.50 or more and 0.95 or less at a measurement temperature of 25? C., and an inclination of SQ obtained from SQ at a measurement temperature of 10? C., SQ at a measurement temperature of 25? C., and SQ at a measurement temperature of 40? C. is ?0.0050? C..sup.?1 or more and ?0.0003? C..sup.?1 or less; a magnetic tape cartridge including the magnetic recording medium which is a magnetic tape; and a magnetic recording and reproducing device including the magnetic recording medium.

There is provided an oriented body containing platinum group-substituted-6 iron oxide particles typified by Rh-substituted -iron oxide or Ru-substituted -iron oxide applicable to MAMR, MIMR, or F-MIMR system, and a technique related thereto, containing platinum group element-substituted -iron oxide particles in which a part of -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.

There is provided an oriented body containing platinum group-substituted-6 iron oxide particles typified by Rh-substituted -iron oxide or Ru-substituted -iron oxide applicable to MAMR, MIMR, or F-MIMR system, and a technique related thereto, containing platinum group element-substituted -iron oxide particles in which a part of -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.

An apparatus is disclosed. The apparatus includes a storage layer, a first write layer, and a second write layer. The first write layer is disposed over the storage layer. The second write layer is disposed over the first write layer. The anisotropy field and magnetization associated with the second write layer at writing temperature is greater than anisotropy field and magnetization associated with the first write layer at the writing temperature.