Abstract: The magnetic recording medium includes a non-magnetic support; and a magnetic layer including a ferromagnetic powder, in which the ferromagnetic powder is a ferromagnetic powder selected from the group consisting of a hexagonal strontium ferrite powder and an ?-iron oxide powder, the number of recesses having a depth which is ? or more of a minimum recording bit length existing on a surface of the magnetic layer is less than 10/10,000 ?m2, and a ratio d/tmag of a value d which is ? of the minimum recording bit length to a thickness tmag of the magnetic layer is 0.15 to 0.50.

Abstract: Provided is a hexagonal ferrite magnetic powder for a magnetic recording medium, containing hexagonal ferrite magnetic particles having aluminum hydroxide adhered on the surface thereof, the hexagonal ferrite magnetic powder having an Al/Fe molar ratio of 0.030 to 0.200, a Co/Fe molar ratio of 0.002 to 0.030, and a Nb/Fe molar ratio of 0.005 to 0.050, and having an Fe site valence AFe of 3.015 to 3.040 as calculated by AFe=(3+2×[Co/Fe]+5×[Nb/Fe])/(1+[Co/Fe]+[Nb/Fe]) wherein [Co/Fe] represents the Co/Fe molar ratio and [Nb/Fe] represents the Nb/Fe molar ratio, and preferably having an activation volume Vact of 1400 to 1800 nm3. This magnetic powder simultaneously achieves an increase in magnetic characteristics including SNR of a magnetic recording medium and a further increase in durability thereof.

Abstract: A tape-shaped magnetic recording medium includes a substrate; and a magnetic layer that is provided on the substrate and contains a magnetic powder. An average thickness of the magnetic layer is not more than 90 nm, an average aspect ratio of the magnetic powder is not less than 1.0 and not more than 3.0, the coercive force Hc1 in a vertical direction is not more than 3000 Oe, the coercive force Hc1 in the vertical direction and a coercive force Hc2 in a longitudinal direction satisfy a relationship of Hc2/Hc1?0.8, and a value of ?1.5??0.5 is not more than 0.6 N in a tensile test of the magnetic recording medium in the longitudinal direction, where ?0.5 is a load at an elongation rate of 0.5% in the magnetic recording medium and ?1.5 is a load at an elongation rate of 1.5% in the magnetic recording medium.

Abstract: Provided is a magnetic tape in which a vertical direction squareness ratio and/or a longitudinal direction squareness ratio obtained by measurement performed by sweeping an external magnetic field in the magnetic tape in a predetermined range by a vibrating sample magnetometer is 0.70 to 1.00, and A calculated by Expression 1 is equal to or smaller than 5.0%. In Expression 1, n represents the number of measurement points measured at magnetic field strength of ?40 kA/m to 40 kA/m during the sweeping and is 52, Mr(Hex) represents a magnetization quantity measured at magnetic field strength Hex, and ? represents an arithmetical mean of Mr(Hex) obtained by measurement performed in the range of the magnetic field strength during the sweeping.

Abstract: The magnetic tape device includes: a magnetic tape; and a servo head, in which a magnetic tape transportation speed of the magnetic tape device is equal to or lower than 18 m/sec, the servo head is a magnetic head including a tunnel magnetoresistance effect type element as a servo pattern reading element, the magnetic tape includes a non-magnetic support, and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, the magnetic layer includes a servo pattern, and a coefficient of friction measured regarding a base portion of a surface of the magnetic layer is equal to or smaller than 0.30.

Abstract: The magnetic tape device includes: a magnetic tape; and a servo head, in which a magnetic tape transportation speed of the magnetic tape device is equal to or lower than 18 m/sec, the servo head is a magnetic head including a tunnel magnetoresistance effect type element as a servo pattern reading element, the magnetic tape includes a non-magnetic support, and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, the magnetic layer includes a servo pattern, and a coefficient of friction measured regarding a base portion of a surface of the magnetic layer is equal to or smaller than 0.30.

Abstract: The magnetic tape device includes: a magnetic tape; and a servo head, in which a magnetic tape transportation speed of the magnetic tape device is equal to or lower than 18 m/sec, the servo head is a magnetic head including a tunnel magnetoresistance effect type element as a servo pattern reading element, the magnetic tape includes a non-magnetic support, and a magnetic layer including ferromagnetic powder and a binding agent on the non-magnetic support, the magnetic layer includes a servo pattern, and a coefficient of friction measured regarding a base portion of a surface of the magnetic layer is equal to or smaller than 0.30.

Abstract: A carrier core material is provided that is formed with ferrite particles which can uniformly adhere a coupling agent to the entire surface. A carrier core material is formed with ferrite particles, and the powder pH of the ferrite particles is equal to or more than 9. Here, the ferrite particles are preferably formed of Mn ferrite or Mn—Mg ferrite. The ferrite particles preferably contain 45 wt % or more but 65 wt % or less of Fe, 15 wt % or more but 30 wt % or less of Mn and 5 wt % or less of Mg.

Abstract: The method of manufacturing hexagonal ferrite powder includes preparing a hexagonal ferrite precursor by mixing an iron salt and a divalent metal salt in a water-based solution, and converting the hexagonal ferrite precursor into hexagonal ferrite within a reaction flow passage, within which a fluid flowing therein is subjected to heating and pressurizing, by continuously feeding a water-based solution containing the hexagonal ferrite precursor and gelatin to the reaction flow passage.

Abstract: An aspect of the present invention relates to magnetic powder, which is magnetoplumbite hexagonal strontium ferrite magnetic powder comprising 1 atomic percent to 5 atomic percent of Ba per 100 atomic percent of Fe, the average particle size of which ranges from 10 nm to 25 nm, and which is magnetic powder for magnetic recording.

Abstract: An aspect of the present invention relates to magnetic powder, which is magnetoplumbite hexagonal strontium ferrite magnetic powder comprising 0.05 atomic percent to 3 atomic percent of Ca per 100 atomic percent of Fe, but comprising no rare earth elements or transition metal elements other than Fe, the average particle size of which ranges from 10 nm to 25 nm, and which is magnetic powder for magnetic recording.

Abstract: An aspect of the present invention relates to a method of manufacturing hexagonal ferrite magnetic powder. The method of manufacturing hexagonal ferrite magnetic powder comprises wet processing hexagonal ferrite magnetic particles obtained following acid treatment in a water-based solvent to prepare an aqueous magnetic liquid satisfying relation (1) relative to an isoelectric point of the hexagonal ferrite magnetic particles: pH0?pH*?2.5, wherein, pH0 denotes the isoelectric point of the hexagonal ferrite magnetic particles and pH* denotes a pH of the aqueous magnetic liquid, which is a value of equal to or greater than 2.0, adding a surface-modifying agent comprising an alkyl group and a functional group that becomes an anionic group in the aqueous magnetic liquid to the aqueous magnetic liquid to subject the hexagonal ferrite magnetic particles to a surface-modifying treatment, and removing the water-based solvent following the surface-modifying treatment to obtain hexagonal ferrite magnetic particles.

Abstract: An aspect of the present invention relates to a hexagonal ferrite magnetic powder manufactured by a glass crystallization method as well as having an average plate diameter ranging from 15 to 25 nm, an average plate ratio ranging from 2.0 to 2.8 and a coercive force (Hc) ranging from 159 to 279 kA/m.

Abstract: An aspect of the present invention relates to hexagonal ferrite magnetic powder, which has an activation volume ranging from 900 nm3 to 1,600 nm3, and a ratio of a coefficient of plate thickness variation to a coefficient of particle diameter variation, coefficient of plate thickness variation/coefficient of particle diameter coefficient, ranging from 0.20 to 0.60.

Abstract: An aspect of the present invention relates to a magnetic tape comprising a magnetic layer containing a hexagonal ferrite magnetic powder and a binder on a nonmagnetic support, wherein a standard deviation ?Hk of a magnetic anisotropy constant Hk of the magnetic layer is equal to or less than 30%, and a magnetic interaction ?M as calculated by equation (1) below falls within a range of ?0.20??M??0.03: ?M=(Id(H)+2Ir(H)?Ir(?))/Ir(?) . . . (1) wherein Id(H) denotes a residual magnetization measured with DC demagnetization, Ir(H) denotes a residual magnetization measured with AC demagnetization, and Ir(?) denotes a residual magnetization measured at an applied magnetic field of 796 kA/m.

Abstract: An aspect of the present invention relates to a magnetic recording medium, which comprises a magnetic layer comprising ferromagnetic powder and binder on a nonmagnetic support, wherein the ferromagnetic powder is ferromagnetic hexagonal ferrite powder comprising 3 to 12 weight percent of Al, based on Al2O3 conversion, relative to 100 weight percent of a total weight of the powder, the magnetic layer further comprises abrasive, and a maximum plan view surface area of the abrasive as determined for a 4.3 ?m×6.3 ?m rectangular region of the magnetic layer by a scanning electron microscope is less than 0.06 percent relative to 100 percent of a total surface area of the region.

Abstract: An aspect of the present invention relates to a method of manufacturing a hexagonal ferrite magnetic particle comprising melting an Al-containing starting material mixture to prepare a melt and quenching the melt to obtain an amorphous material; subjecting the amorphous material to heat treatment to cause a hexagonal ferrite magnetic particle to precipitate in a product obtained by the heat treatment; collecting a hexagonal ferrite magnetic particle by subjecting the product to treatment with an acid and washing, wherein the hexagonal ferrite magnetic particle collected has a particle size ranging from 15 to 30 nm, comprises 0.6 to 8.0 weight percent of Al, based on Al2O3 conversion, relative to a total weight of the particle, and Al adheres to a surface of the hexagonal ferrite magnetic particle.

Abstract: An aspect of the present invention relates to a magnetic tape comprising a magnetic layer containing a ferromagnetic powder and a binder on a nonmagnetic support, wherein the ferromagnetic powder is a hexagonal ferrite powder, squareness in a vertical direction without demagnetizing field correction of the magnetic layer ranges from 0.6 to 1.0, and the magnetic layer further comprises a compound in which a substituent selected from the group consisting of a carboxyl group and a hydroxyl group is directly substituted into a ring structure comprising a double bond and having a ClogP falling within a range of 2.3 to 5.5.

Abstract: An aspect of the present invention relates to a method of manufacturing hexagonal ferrite magnetic powder. The method of manufacturing hexagonal ferrite magnetic powder comprises wet processing hexagonal ferrite magnetic particles obtained following acid treatment in a water-based solvent to prepare an aqueous magnetic liquid satisfying relation (1) relative to an isoelectric point of the hexagonal ferrite magnetic particles: pH0?pH*?2.5, wherein, pH0 denotes the isoelectric point of the hexagonal ferrite magnetic particles and pH* denotes a pH of the aqueous magnetic liquid, which is a value of equal to or greater than 2.0, adding a surface-modifying agent comprising an alkyl group and a functional group that becomes an anionic group in the aqueous magnetic liquid to the aqueous magnetic liquid to subject the hexagonal ferrite magnetic particles to a surface-modifying treatment, and removing the water-based solvent following the surface-modifying treatment to obtain hexagonal ferrite magnetic particles.

Abstract: An aspect of the present invention relates to a hexagonal barium ferrite magnetic particle, wherein, relative to 100 atom percent of a Fe content, an Al content ranges from 1.5 to 15 atom percent, a combined content of a divalent element and a pentavalent element ranges from 1.0 to 10 atom percent, an atomic ratio of a content of the divalent element to a content of the pentavalent element is greater than 2.0 but less than 4.0, and an activation volume ranges from 1,300 to 1,800 nm3.

Abstract: The magnetic signal reproduction system comprises a magnetic recording medium comprising a magnetic layer comprising a ferromagnetic powder and a binder on a nonmagnetic support; and a reproduction head, wherein a number of protrusions equal to or greater than 10 nm in height on the magnetic layer surface, as measured by an atomic force microscope, ranges from 50 to 2500/10,000 ?m2, a quantity of lubricant on the magnetic layer surface, denoted as a surface lubricant index, ranges from 0.5 to 5.0, a surface abrasive occupancy of the magnetic layer ranges from 2 to 20 percent, and the reproduction head is a magnetoresistive magnetic head comprising a spin-valve layer.

Abstract: An aspect of the present invention relates to a method of manufacturing a hexagonal ferrite magnetic particle comprising melting an Al-containing starting material mixture to prepare a melt and quenching the melt to obtain an amorphous material; subjecting the amorphous material to heat treatment to cause a hexagonal ferrite magnetic particle to precipitate in a product obtained by the heat treatment; collecting a hexagonal ferrite magnetic particle by subjecting the product to treatment with an acid and washing, wherein the hexagonal ferrite magnetic particle collected has a particle size ranging from 15 to 30 nm, comprises 0.6 to 8.0 weight percent of Al, based on Al2O3 conversion, relative to a total weight of the particle, and Al adheres to a surface of the hexagonal ferrite magnetic particle.

Abstract: A magnetic recording medium is provided that includes a non-magnetic support, a radiation-cured layer cured by exposing a layer containing a radiation curing compound to radiation, and a magnetic layer comprising a ferromagnetic powder dispersed in a binder. The radiation-cured layer and the magnetic layer are provided in that order above the non-magnetic support. The radiation curing compound has a C2 to C18 alkyl group, a C6 to C10 cyclic structure, and two or more radiation curing functional groups per molecule.

Abstract: An aspect of the present invention relates to a method of manufacturing a hexagonal ferrite magnetic powder comprising preparing a melt by melting a starting material mixture, wherein the starting material mixture comprises at least one hexagonal ferrite-forming component and glass-forming component comprising at least one B2O3 component and a content of the B2O3 component in the mixture ranges from 15 to 27 mole percent in terms of B2O3; rapidly cooling the melt to obtain a solid having a saturation magnetization level of equal to or lower than 0.6 A·m2/kg; and heating the solid to a temperature range of 600 to 690° C. and maintaining the solid within the temperature range to precipitate a hexagonal ferrite magnetic powder having an average plate diameter ranging from 15 to 25 nm.

Abstract: The present invention relates to a magnetic recording medium comprising a magnetic layer comprising a hexagonal ferrite powder and a binder on one surface of a nonmagnetic support and a backcoat layer on the other surface of the nonmagnetic support. A power spectrum density at a pitch of 10 micrometers ranges from 800 to 10,000 nm3 on the magnetic layer surface, a power spectrum density at a pitch of 10 micrometers ranges from 20,000 to 80,000 nm3 on the backcoat layer surface, the magnetic layer has a center surface average surface roughness Ra, as measured by an atomic force microscope, ranging from 0.5 to 2.5 nm, and the hexagonal ferrite powder has an average plate diameter ranging from 10 to 40 nm.

Abstract: A recording and reproducing apparatus includes: a recording section for recording an information signal in a magnetic recording medium including a magnetic layer including hexagonal ferrite; a reproducing section for reproducing the information signal recorded in the magnetic recording medium, the reproducing section including: a reproducing head for reading the information signal from the magnetic recording medium; an equalizer for equalizing the information signal read from the magnetic recording medium, wherein a partial response of the information signal after equalization by the equalizer satisfies a condition that 0.4?a<3.0, ?0.6?b<2.0, ?2.0<c??0.2, ?3.0<d??0.4, and ?1.0<e?0.0. A corresponding reproducing method, a corresponding reproducing apparatus, and the magnetic recording medium are also disclosed.

Abstract: Provided is a magnetic recording medium exhibiting good electromagnetic characteristics in high-density recording The magnetic recording medium employed for magnetically recording signals with a track width equal to or less than 2.0 ?m and reproducing the magnetically recorded signals, wherein said magnetic recording medium comprises a magnetic layer comprising a hexagonal ferrite ferromagnetic powder and a binder or comprises a nonmagnetic layer comprise a nonmagnetic powder and a binder and a magnetic layer comprising a hexagonal ferrite ferromagnetic powder and a binder in this order on a nonmagnetic support. Said magnetic layer has a thickness equal to or less than 0.2 ?m, and said hexagonal ferrite ferromagnetic powder has an average plate diameter being 1/30 or less of the magnetically recorded track width as well as ½ or less of the thickness of the magnetic layer.

Abstract: A hexagonal ferrite magnetic powder having an average tabular diameter of from 15 to 28 nm, a coercive force (Hc) of from 2,000 to 5,000 Oe (from 160 to 400 kA/m), a switching field distribution (SFD) of from 0.3 to 0.7 and a D70/D50 of from 1.05 to 1.25. This magnetic powder can be obtained by melting and quenching starting materials to obtain an amorphous product, and thermally treating the product, which comprises increasing a temperature at a rate of 300 to 500° C./hr in a temperature range of 550 to 600° C. in the thermal treatment before the temperature reaches the thermally treating temperature.

Abstract: A magnetic recording medium including: a back coat layer; a nonmagnetic support; and coated layers including: a nonmagnetic layer containing nonmagnetic powder and a binder; and a magnetic layer containing ferromagnetic powder and a binder, so that the back coat layer, the nonmagnetic support, the nonmagnetic layer and the magnetic layer are provided in this order, wherein the ferromagnetic powder is ferromagnetic hexagonal ferrite powder having an average tabular size of less than 30 nm, and a central plane surface roughness Ra of the magnetic layer, a central plane surface roughness Ra of the back coat layer, a glass transition point of the coated layers, a glass transition point of the back coat layer and a ratio of a Young's modulus of the magnetic layer to a Young's modulus of the back coat layer are defined herein.

Abstract: The present invention provides a magnetic recording medium having a magnetic layer formed on at least one surface of a nonmagnetic support, wherein the magnetic layer includes a ferrite ferromagnetic hexagonal powder having an average plate diameter of 5 to 50 nm or a fine ferromagnetic metal powder having an average major axis length of 20 to 100 nm together with a binder, and the nonmagnetic support is a composition of a polyester or copolyester having one or more of polytrimethylene 2,6-naphthalate, polytetramethylene 2,6-naphthalate, polypentamethylene 2,6-naphthalate and polyhexamethylene 2,6-naphthalate, in order to provides an excellent running stability, low error rates under various environment and an excellent electromagnetic transforming properties and reliability.

Abstract: A ferrite magnet obtained by adding a ferrite having a hexagonal W-type magnetoplumbite structure to a ferrite having a hexagonal M-type magnetoplumbite structure, in which a portion of Sr, Ba, Pb or Ca is replaced with at least one element that is selected from the group consisting of the rare-earth elements (including Y) and Bi and that always includes La, during the fine pulverization process thereof. By adding a small amount of the element such as Co, Ni, Mn or Zn to the ferrite already having the hexagonal M-type magnetoplumbite structure during the fine pulverization process thereof, the magnetic properties can be improved.

Abstract: A hexagonal ferrite magnetic powder having an average tabular diameter of from 15 to 30 nm, a coercive force (Hc) of from 2,000 to 5,000 Oe (from 160 to 400 kA/m) and a saturated magnetization (?s) of equal to or more than the average tabular diameter (nm)×0.37+45 A·m2/kg. This magnetic powder is obtained by melting a starting material containing a material which has a composition within the hatched region (1) in the triangular phase diagram shown in FIG. 1 and quenching the molten product to obtain an amorphous product, subjecting the amorphous product to a thermal treatment, acid treatment, and washing. Also, a magnetic recording medium is obtained by adding this magnetic powder to the magnetic layer and coating it on the support.

Abstract: To provide a magnetic recording medium which undergoes little effect of thermal fluctuation and provides a high short wavelength output and C/N ratio when reproduction is conducted using MR head, the magnetic recording medium includes a non-magnetic layer having a non-magnetic powder dispersed in a binder provided on a support and a magnetic layer having a ferromagnetic powder dispersed in a binder provided on the non-magnetic layer, wherein the ferromagnetic powder comprises a hexagonal ferrite magnetic powder having an average diameter of from 10 to 35 nm and a coercive force of from 135 to 400 kA/m; the magnetic layer has a coercive force of from 135 to 440 kA/m; and a product of an anisotropic magnetic field of the magnetic layer and an average particle volume of the hexagonal ferrite magnetic powder is from 1.2×106 to 2.4×106 kA/m·nm3.