Governor of Akita Prefecture

Japan Science and Technology Agency

Akita Prefecture

Governor of Akita Perfecture

Naoki Honda

Kazuhiro Ouchi

Toshio Suzuki

Atsushi Kikawada

A method of designing a patterned magnetic recording medium including a magnetic film with perpendicular magnetic anisotropy which is patterned into dots form includes steps of setting values to dot pattern periods Pand P, a thickness 't', a thermal stability factor K, a minimum inter-dot spacing S, and a maximum recording field H, setting an initial value of a saturation magnetization M, finding a nucleation field for magnetization reversal Hand estimating a coercivity Hand a saturation field H, and repeating the steps given above so as to make the saturation field Hlower than the maximum recording field H, thereby determining the magnetic properties M, Hand Hsatisfying a desired condition.

Method of designing patterned magnetic recording medium and patterned magnetic recording medium

To present an information recording medium for achieving high density information recording, in particular, a high signal output and a high resolution in magnetic recording, for example, an information recording medium sequentially forming a layer made of soft magnetic material, a layer made of nonmagnetic material, and an information recording layer of ordered alloy with L crystal structure selected from group A is manufactured in a specified manufacturing method. Herein the group A is defined to include FePt ordered alloy, CoPt ordered alloy, FePd ordered alloy, and their alloy.

High density information recording medium, and manufacturing method of the same medium

An information recording layer consisting of a composite of an ordered alloy of L1 crystal structure selected from a group A, and MgO is used for a perpendicular magnetic recording medium. The group A includes an FePt ordered alloy, a CoPt ordered alloy, an FePd ordered alloy and an alloy thereof. This information recording layer has a very small magnetic domain structure and allows high density recording as seen from a signal output spectrum showing a result of a recording and reproducing evaluation of a magnetic recording medium in one example. The information recording layer can be formed at lower film formation temperature than a temperature of a composite thin film of an ordered alloy of L1 crystal structure according to a conventional technique.

Magnetic recording medium

A data recording device such as a hard disk apparatus has an orthogonal coding circuit and a modulation circuit. The orthogonal coding circuit encodes recording data to be recorded to adjacent two tracks as two orthogonal code streams which are included in an Hadamard matrix. The modulation circuit outputs recording signals, which are obtained by modulating the code streams using the NRZI system, to a magnetic head. Reproduction signals read out from a magnetic disk by the magnetic head are decoded as recording data based upon given decoding rules according to the two code streams.

Data recording and reproducing apparatus using two orthogonal code

A method of manufacturing a data recording medium for recording and reproducing data by use of a magnetic field or light and formed of an ordered alloy thin film comprising the steps of forming at least one underlayer principally containing an element or a compound selected from the group consisting of Cr, Pt, Pd, Au, Fe, Ni, MgO, NiO and controlled in such a way that a crystal plane having a crystal lattice face of a Miller index (100) is in parallel to a substrate, and forming an ordered alloy layer with L1.sub.0 crystal structure by sputter deposition within the range satisfying Equation 1: P.times.D&gt;3000, where P is Ar sputter-gas pressure (Pa) and D is a target-substrate distance (mm), is disclosed. When a recording medium is formed of an ordered alloy thin film by using a glass substrate for a hard disk for industrial use, according to the method of the present invention, formation of an ordered phase required for exhibiting large magnetocrystalline anisotropy is accelerated at a low temperature allowing usage of the glass substrate, so that the recording medium is improved in thermal stability.

Method of manufacturing data recording medium made of ordered alloy thin

A thin film magnetic recording medium comprising, a substrate, a crystal orientation enhancement underlayer of hcp structure formed on the substrate, a perpendicular orientation dispersion angle of c-axis thereof being not more than 10 degrees, and a cobalt-chromium-based magnetic layer formed on the underlayer, the magnetic layer having a thickness of 100 nm or less and containing 1 to 8 at % of niobium.

Growing community of inventors

Akita, Japan

Naoki Honda