Tdk Corporation

Shinji Miyazaki

Jiro Yoshinari

Hiroyasu Inoue

Koji Kobayashi

Mitsuru Takai

Kunihiro Ueda

Hiroshi Shingai

Masanori Kosuda

Tsunehiko Ikarashi

Hiromichi Kanazawa

Masahide Kohno

The magneto-optical recording medium of the present invention has a triple-layer magnetic laminate on the surface side of the substrate, and the magnetic laminate comprises an amplification layer A.sub.1, an exchange coupling control layer C.sub.12 and a recording layer R.sub.2 formed in this order. In the recording of the medium, magnetic domain is formed in the recording layer R.sub.2 and, and in the reproduction of the medium, the magnetic domain in R.sub.2 is copied to A.sub.1 to form a copied magnetic domain simultaneously with the enlarging of the thus formed copied magnetic domain in A.sub.1 by irradiation of a laser beam and application of a reproduction magnetic field. In the present invention, the amplification layer A.sub.1 does not have a compensation temperature higher than room temperature. Curie temperature Tc.sub.A1 of the amplification layer A.sub.1, Curie temperature Tc.sub.C12 of the exchange coupling control layer C.sub.12, and Curie temperature Tc.sub.S12 of the switching layer S.sub.12 are either Tc.sub.A1 &lt;Tc.sub.C12 ; or Tc.sub.S12 is higher than room temperature and Tc.sub.S12 &lt;Tc.sub.A1. Intensity of the reproduced signals are thereby sufficiently increased.

Magneto-optical recording medium

A magneto-optical recording medium capable of direct overwriting in a light intensity modulation mode comprises a magnetic multilayer structure comprising, in order form an surface side thereof, a readout layer R.sub.01, a memory layer M.sub.1, an exchange force control layer C.sub.12 and a recording layer W.sub.2, four layers in all. The magnetic multilayer structure satisfies TC.sub.W2 &gt;Tc.sub.M1, t.sub.R01 /(t.sub.R01 +t.sub.M1)=0.3 to 0.6, and t.sub.R01 +t.sub.M1 =20 to 40 nm where Tc.sub.M1 is a Curie temperature of M.sub.1, Tc.sub.W2 is a Curie temperature of W.sub.2, t.sub.R01 is a thickness of R.sub.01, and t.sub.M1 is a thickness of M.sub.1. R.sub.01 contains Gd, Fe, and Co as main components with the proviso that Gd is contained in an amount of 23 to 27 at %, M.sub.1 contains Tb, Fe, and Co as main components with the proviso that Tb is contained in an amount of 21 to 25 at %, and C.sub.12 contains Gd, Fe, and Co as main components with the proviso that Gd is contained in an amount of 23 to 32 at %, and has a thickness of 30 nm or below.

A magnetic recording medium includes a non-magnetic supporting substrate, and a magnetic layer on one surface thereof and a back coat layer on the other surface thereof, said back coat layer having a non-magnetic powder dispersed in a binder. The back coat layer contains carbon black and an inorganic powder as said non-magnetic powder. The carbon black contains a carbon black species having an average primary particle diameter of 40 to 70 nm, and the inorganic powder has an average primary particle diameter of 40 to 150 nm and a Mohs hardness of at least 3, with a weight ratio between said carbon black and said inorganic powder being 100:0.5 to 100:10. The binder comprises a phenoxy resin, a thermoplastic polyurethane resin having an amino group in a molecule thereof, and a polyisocyanate compound.

Magnetic recording medium

A magneto-optical recording medium comprises a substrate, and a magnetic multilayer 4 on a surface side thereof. The magnetic multilayer comprises an amplifying layer A.sub.1 and a recording layer R.sub.2 which are laminated together and are each a magnetic layer. A nonmagnetic intermediate layer I.sub.12 is interleaved between the amplifying layer A.sub.1 and the recording layer R.sub.2 to couple them magnetostatically. The nonmagnetic intermediate layer I.sub.12 is made up of a metal oxide and has a thickness of 2 to 30 nm. The magnetic field intensity needed for magnetic field modulation reading or light modulation reading can be lowered.

Magneto-optical recording medium having an enlarged magnetic domain in

The invention provides a phase charge type optical recording medium comprising on both sides of a recording layer dielectric layers, each containing zinc sulfide and silicon oxide as main components. The medium comprises on a substrate 2 a first dielectric layer 31, a recording layer 4, a second dielectric layer 32 and a reflective layer 5 made up of a metal. The first dielectric layer 32 comprises a dielectric lamina 1a on a substrate 2 side thereof and a dielectric lamina 1b on a recording layer 4 side thereof. The dielectric lamina 1a has a silicon oxide content of 2 to less than 40 mol %, the dielectric lamina 1b has a silicon oxide content of 40 to 100 mol %, and the second dielectric layer 32 has a silicon oxide content of 2 to 50 mol % and a thickness of 10 to 35 nm. The number of overwritable cycles can be increased.

Optical recording medium and read/write method therefor

In reading a magneto-optical recording medium comprising a substrate and a magnetic multilayer on a surface of the substrate, which multilayer comprises, in order from the surface of the substrate, an amplifying layer A.sub.1, a control layer C.sub.2, and a recording layer R.sub.3 with a magnetic domain formed therein, the medium is first irradiated with a laser beam while a reading magnetic field is applied thereto in one direction. With the resulting temperature increase, the magnetic domain in R.sub.3 is successively copied from C.sub.2 to A.sub.1 to form copied magnetic domains, which are in turn enlarged by a reading magnetic field. Then, the enlarged, copied magnetic domain in A.sub.1 is read out. Thereupon, laser beam irradiation is interrupted or the power of the laser beam is decreased to thereby vanish the copied magnetic domains in A.sub.1 and C.sub.2. To carry out reading by light intensity modulation, an interface wall exchange force magnetic field between the respective magnetic layer, etc. is controlled, so that reading can take place with no application of a modulated magnetic field.

Magneto-optical recording medium with a layer to enlarge magnetic domains

The invention is directed at a magneto-optical recording medium which is directly overwritable by light intensity modulation, does not require an initializing magnet, and has on the surface side of a substrate four magnetic layers, a memory layer M.sub.1, a writing layer W.sub.2, a switching layer S.sub.3, and an initializing layer I.sub.4. The magnetic layers each contain a rare earth element and a transition element, have perpendicular magnetic anisotropy at room temperature, and satisfy the relationships:

The invention provides a method which can be performed on the same device with application of a modulated magnetic field to read a magneto-optical recording disk through a series of processes involving 'copy of recorded magnetic domains.fwdarw.enlargement of copied magnetic domains.fwdarw.reproduction of copied magnetic domains.fwdarw.size reduction and disappearance of copied magnetic domains', and to read an ordinary magneto-optical recording medium. For reading information recorded on the first magneto-optical recording disk, the first magneto-optical recording disk is irradiated with a laser beam having a first reading power, and the alternating magnetic field is then applied thereto after synchronization by which the alternating magnetic field is applied thereto at a recorded mark position. For reading information recorded on the second magneto-optical recording disk, the second magneto-optical recording disk is irradiated with a second laser beam.

Reading method for magneto-optical recording disc, magneto-optical

Method for forming film by plasma polymerization and apparatus for

In the present invention, data transmission rate is increased in the recording of the magneto-optical recording media in which the reproduction is accomplished by applying a modulated magnetic field in a scheme of 'copying of the recorded magnetic domain.fwdarw.enlargement of the copied magnetic domain.fwdarw.reproduction of the copied magnetic domain .fwdarw.size reduction and disappearance of the copied magnetic domain'. The recording/reproducing method of the present invention is adapted for use with a magneto-optical recording medium having a magnetic lamination comprising a recording layer and an amplification layer wherein recording is accomplished by applying a modulated recording magnetic field, and reproduction is accomplished by applying 1 cycle of the modulated magnetic field (reproduction magnetic field+erase magnetic field) per 1 record mark (1 bit). In the recording/reproducing method of the present invention, the recording and the reproduction are conducted such that:

Recording/reproducing method of magneto-optical recording medium and

A magnetic recording medium having excellent electromagnetic characteristics, still characteristics and cupping resistance, reduced rust generation and increased durability, comprises a non-magnetic substrate and a magnetic layer formed thereon by oblique deposition, the magnetic layer being composed of at least two ferromagnetic metal thin films containing Co and Ni as main components, in which the Co content of the thin film closest to the substrate is less than 70 atomic per cent and the Co content of the film farthest from the substrate is 75 atomic per cent or more.

A magnetic recording medium having excellent electromagnetic characteristics, still characteristics and cupping, decreased rust generation and high durability, includes a non-magnetic substrate and a magnetic layer formed thereon by oblique deposition, the magnetic layer being composed of at least two ferromagnetic thin films, in which the ferromagnetic thin film of the lowest layer has a saturation magnetization of 300 emu/cc or less, a coercive force of 1000 Oe or less and a thickness of 300 to 1500 .ANG., the ferromagnetic thin layer of the uppermost layer has a saturation magnetization of 300 emu/cc or more, a coercive force of 1000 Oe or more and a thickness of 400 to 1500 .ANG., an average value (.theta.) of angles between growing directions of columnar crystalline particles constituting the ferromagnetic thin film of the lowest layer and a principal plane of the substrate ranges from 50 to 70 degrees, and an average value (.theta.) of angles between growing directions of columnar crystalline particles constituting the ferromagnetic thin film of the uppermost layer and the principal plane of the substrate ranges from 30 to 50 degrees.

A magnetic recording medium comprising a nonmagnetic base, an SiO.sub.x (x=1.2-1.95) undercoat, an under-layer ferromagnetic metal film consisting of a Co--Ni alloy, an SiO.sub.x (x=1.2-1.95) intermediate layer, an upper-layer ferromagnetic metal protective film consisting of a Co--Ni alloy, a diamond-like carbon protective film, and a lubricant layer, formed in the order of mention, the angles of vapor deposition as measured from lines normal to the upper- and under-layer ferromagnetic metal films being all decreasing toward the upper surfaces. The magnetic recording medium is made by forming an SiO.sub.x (x=1.2-1.95) undercoat by vapor deposition on a flexible nonmagnetic base being fed, forming an under-layer ferromagnetic metal film by vapor deposition of a Co--Ni alloy at a large deposition angle on the supply side and at a small deposition angle on the take up side, rewinding the semi-finished product thus obtained, repeating the foregoing process steps, forming a diamond-like carbon protective film, and further forming a lubricant layer over the diamond-like carbon protective film, all within a vacuum chamber.

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Nagano, Japan

Shinji Miyazaki