1124results about "Magnetic materials for record carriers" patented technology

A magnetic disk including a substrate, a recording track section which is made of a magnetic member for recording and reproducing information magnetically and is provided on the substrate, and a guard band member which is provided between the recording track sections adjacent to each other so that they are substantially continued in a track direction and is harder than the magnetic member and is made of a non-magnetic material. Moreover, the magnetic member is not provided or magnetic members with a different thickness from the magnetic member forming the recording track section is provided on a lower area of the guard band member.

A perpendicular magnetic recording medium comprising a substrate, a soft underlayer, a seed layer, a non-magnetic FCC NiW alloy underlayer, a non-magnetic HCP underlayer, and a magnetic layer. We have discovered that the combination of a seed layer comprising Ta and a NiW alloy underlayer uniquely improves media recording performance and thermal stability by achieving excellent coercivity of the thin bottom magnetic recording layer and narrow C axis orientation distribution.

A STT-RAM MTJ is disclosed with a MgO tunnel barrier formed by natural oxidation and containing an oxygen surfactant layer to form a more uniform MgO layer and lower breakdown distribution percent. A CoFeB/NCC/CoFeB composite free layer with a middle nanocurrent channel layer minimizes Jc₀ while enabling thermal stability, write voltage, read voltage, and Hc values that satisfy 64 Mb design requirements. The NCC layer has RM grains in an insulator matrix where R is Co, Fe, or Ni, and M is a metal such as Si or Al. NCC thickness is maintained around the minimum RM grain size to avoid RM granules not having sufficient diameter to bridge the distance between upper and lower CoFeB layers. A second NCC layer and third CoFeB layer may be included in the free layer or a second NCC layer may be inserted below the Ru capping layer.

An aspect of the present invention relates to a magnetic tape comprising, on one surface of a nonmagnetic support, a nonmagnetic layer containing a nonmagnetic powder and a binder, and thereon, a magnetic layer containing a ferromagnetic powder and a binder, wherein

• • the magnetic layer contains a nonmagnetic filler the average particle diameter φ of which satisfies relation (I) below with a thickness t of the magnetic layer:

1.0≦φ/t≦2.0  (I);

• • the thickness t of the magnetic layer ranges from 30 to 200 nm;
  • the nonmagnetic layer has a thickness ranging from 30 to 200 nm;
  • a composite elastic modulus as measured on a surface of the magnetic layer ranges from 6.0 to 8.0 GPa; and
  • a centerline average surface roughness Ra of the surface of the magnetic layer, as measured by an optical three-dimensional profilometer, ranges from 0.2 to 1.5 nm.

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.

Provided are a magnetic recording medium, in which a magnetic layer includes ferromagnetic hexagonal ferrite powder, a binding agent, and an oxide abrasive, an intensity ratio Int(110)/Int(114) obtained by an X-ray diffraction analysis of the magnetic layer by using an In-Plane method is 0.5 to 4.0, a vertical squareness ratio of the magnetic recording medium is 0.65 to 1.00, a logarithmic decrement acquired by a pendulum viscoelasticity test performed regarding a surface of the magnetic layer is equal to or smaller than 0.050, and an average particle diameter of the oxide abrasive obtained from a secondary ion image obtained by irradiating the surface of the magnetic layer with a focused ion beam is 0.04 μm to 0.08 μm, and a magnetic recording and reproducing device including this magnetic recording medium.

Disclosed is a method for producing core-shell type metallic nanoparticles involving (i) providing a dispersion of a first metal as nanoparticles in an appropriate organic solvent; (ii) providing a solution of a metallic precursor containing a second metal in an appropriate organic solvent, in which the second metal has a reduction potential higher than that of the first metal; and (iii) combining the dispersion from (i) and the solution from (ii) together to carry out the transmetalation reaction of the first and second metals, thereby forming core-shell type metallic nanoparticles.

The magnetic tape has a magnetic layer and a backcoat layer, wherein, each of the magnetic layer and backcoat layer contains a fatty acid ester, the Ra measured on the magnetic layer side surface is less than or equal to 2.8 nm, the difference between the spacing measured by optical interferometry on the magnetic layer side surface after and before vacuum heating is greater than 0 nm but less than or equal to 8.0 nm, the FWHM_before on the backcoat layer side surface is greater than 0 nm but less than or equal to 10.0 nm, the FWHM_after on the backcoat layer side surface is greater than 0 nm but less than or equal to 10.0 nm; and the difference between the spacing measured on the backcoat layer side surface after and before vacuum heating is greater than 0 nm but less than or equal to 8.0 nm.

A magnetic recording medium with excellent high density recording performances and good durability comprising a non-magnetic substrate, a non-magnetic layer containing a non-magnetic powder and a binder formed on the non-magnetic substrate, and a magnetic layer having a thickness of less than 100 nm and containing a substantially particulate non-magnetic powder, a substantially particulate magnetic powder having an average particle size of less than 25 nm, and a binder, wherein an average particle size R of the non-magnetic powder contained in the magnetic layer and a thickness D of the magnetic powder satisfy the following relationship: 0.88≦R/D≦2.5.

A magnetoresistive element includes a first underlying layer having an NaCl structure and containing a nitride orienting in a (001) plane, a first magnetic layer provided on the first underlying layer, having magnetic anisotropy perpendicular to a film surface, having an L1₀ structure, and containing a ferromagnetic alloy orienting in a (001) plane, a first nonmagnetic layer provided on the first magnetic layer, and a second magnetic layer provided on the first nonmagnetic layer and having magnetic anisotropy perpendicular to a film surface.

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.

A magnetoresistive element includes a first reference layer having magnetic anisotropy perpendicular to a film surface, and an invariable magnetization, a recording layer having a stacked structure formed by alternately stacking magnetic layers and nonmagnetic layers, magnetic anisotropy perpendicular to a film surface, and a variable magnetization, and an intermediate layer provided between the first reference layer and the recording layer, and containing a nonmagnetic material. The magnetic layers include a first magnetic layer being in contact with the intermediate layer and a second magnetic layer being not in contact with the intermediate layer. The first magnetic layer contains an alloy containing cobalt (Co) and iron (Fe), and has a film thickness larger than that of the second magnetic layer.

An aspect of the present invention relates to a magnetic recording medium comprising a magnetic layer containing a ferromagnetic powder and a binder on a nonmagnetic support, wherein the ferromagnetic powder has a hexagonal ferrite structure, the magnetic layer comprises a coefficient of friction-lowering component in the form of nonmagnetic inorganic particles, and a compound in which a substituent selected from the group consisting of a hydroxyl group and a carboxyl group is directly substituted on an aromatic ring.

An aspect of the present invention relates to a magnetic tape comprising a magnetic layer comprising ferromagnetic powder and binder on a nonmagnetic support, wherein ΔSFD in a longitudinal direction of the magnetic tape as calculated with Equation 1 ranges from 0.35 to 1.50:

ΔSFD=SFD_{25° C.}−SFD_{−190° C.}  Equation 1

wherein, in Equation 1, SFD_{25° C.} denotes a switching field distribution SFD as measured in the longitudinal direction of the magnetic tape in an environment with a temperature of 25° C., and SFD_{−190° C.} denotes a switching field distribution SFD as measured in the longitudinal direction of the magnetic tape in an environment with a temperature of −190° C.

Provided is a magnetic tape in which the total thickness of the non-magnetic layer and the magnetic layer is equal to or smaller than 0.60 μm, the magnetic layer includes ferromagnetic hexagonal ferrite powder and an abrasive, a percentage of a plan view maximum area of the abrasive confirmed in a region having a size of 4.3 μm×6.3 μm of the surface of the magnetic layer by plane observation using a scanning electron microscope, with respect to the total area of the region is equal to or greater than 0.02% and less than 0.06%, and a tilt cos 0 of the ferromagnetic hexagonal ferrite powder with respect to a surface of the magnetic layer acquired by cross section observation performed by using a scanning transmission electron microscope is 0.85 to 1.00.