Sony Corporation

Koichi Aso

Masatoshi Hayakawa

Satoru Uedaira

Yoshitaka Ochiai

Kazuhiko Hayashi

Yoshimi Makino

Kazuhide Hotai

Hideki Matsuda

Shigeyasu Ito

Kenji Katori

Wataru Ishikawa

You Iwasaki

Shunichi Hashimoto

Hidemasa Tamura

Koichi Tatsuki

Hiroshi Yamanoi

Yasunari Sugiyama

Kazutaka Habu

Tsutomu Okamoto

Kazuo Kajiwara

Akihiko Okabe

Takehiro Nagaki

A magneto-optical recording medium is disclosed in which a magneto-optical recording layer is formed by alternately stacking Co layers and Pt and/or Pd layers, and having a total thickness between 50 and 800 .ANG..

Magneto-optical recording medium with stacked layer structure

A magnetic recording and reproducing head records a signal from and reproduces a signal from a magnetic recording medium having a perpendicularly magnetizable film. The magnetic recording and reproducing head includes a magnetic sensing section comprising a slender needle of a soft magnetic material, and an exciting coil wound around the slender needle for magnetizing the slender needle to record a signal on the magnetic recording medium. To reproduced the recorded signal, high-frequency electric energy is applied to the magnetic sensing section to produce a reflected wave, and a change in the reflected wave caused by a leakage magnetic field produced by a signal recorded on the magnetic recording medium is detected as representing the recorded signal.

High-density magnetic recording and reproducing head

A method is provided for producing a KTiOPO.sub.4 which is grown at a temperature higher than its Curie temperature using a TSSG method. The grown KTiOPO.sub.4 single crystal is maintained in contact with a melt while the crystal is maintained at a temperature higher than the Curie temperature. A d.c. current is applied in this state across a seed crystal and the melt, while the single crystal is cooled to a temperature lower than the Curie temperature. The value of current density D, defined by the formula D=Ip/(a+b), where Ip is the impressed current and a, b are crystal sizes along a and b axes, respectively, is selected to be 0.01 mA/cm.sup.2 .ltoreq.D.ltoreq.1.0 mA/cm.sup.2. In this manner, the produced KTiOPO.sub.4 is processed into a single domain crystal.

Method for producing KTIOPO4 single crystal

A magnetic recording medium having a magnetic thin film of a composition expressed as (Co.sub.a Pt.sub.b M.sub.c.sup.I M.sub.d.sup.II) Ox (where a, b, c, d are atomic percent; and x is weight percent). In this composition, a+b+c+d=100, 0&lt;a, 0&lt;b.ltoreq.50, 0&lt;c.ltoreq.20, 0&lt;d.ltoreq.20, 0&lt;x.ltoreq.10. M.sup.I is at least one element selected from P, Si and Ge; and M.sup.II is at least one element selected from B, Ga, Al, In, Sn and Sb. Such magnetic thin film is capable of retaining a large coercive force regardless of its thickness and can be formed without the necessity of raising the base temperature during deposition of a magnetic layer.

Magnetic recording medium

Additive elements are added to Fe-N soft magnetic thin films along with oxygen, so that the thermal stability is remarkably improved. After annealing treatment at approximately 550.degree. C., it is possible to provide an Fe-N soft magnetic thin film with a low coercive force. Similarly, it is also possible to provide a soft magnetic thin film having a low coercive force by introducing a combination of specific types of additive elements to Fe-N soft magnetic thin films. When oxygen is further added to the film, it is also possible to provide a soft magnetic thin film which has very excellent soft magnetic characteristics and good thermal stability. The soft magnetic thin films of the invention have good soft magnetic characteristics, a high saturation magnetic flux density and good thermal stability. A magnetic head of a metal-in-gap type using the soft magnetic thin film is also described.

Fe-N-based soft magnetic thin films and magnetic heads using such films

Disclosed is a soft magnetic thin film having a basic composition of FecoNi or FeCoDy which is specified for use as a single layer film for increasing the saturation magnetic flux density and the coercive force. The soft magnetic properties are achieved by laminating the above defined soft magnetic thin film as the first soft magnetic thin film layer with a second magnetic thin film layer. In this case, crystal structures of the first and the second soft magnetic thin films should appropriately be selected and combined.

Soft magnetic thin films of alloys of FeCoNi or FeCoDy and laminates

A device for producing a high frequency modulating magnetic field is disclosed. The device is especially useful to achieve real-time overwriting in magneto-optical recording. The device produces magnetic field modulated according to a signal to be recorded on a magneto-optical recording medium in which the signal is recorded in the form of magnetization direction on the magneto-optical recording medium under irradiation of a laser beam to raise the temperature of the medium. The device comprises a main magnetic pole formed of a low-loss soft magnetic material and having one end facing to the magnetic-optical recording medium and a sheathed conductor wound around the main magnetic pole and consisting of a parallel connection of a plurality of insulated elementary wires.

Device for producing a high frequency modulation magnetic field used in

A magnetic alloy thin film consisting essentially of a first Fe-Al-Si or Fe-Ni alloy thin film of high permeability and a second Fe-Si alloy thin film directly formed on the first thin film and having high saturation magnetic flux density. The ratio in thickness of the first and second films is preferably in the range of from 1:0.1 to 2.

Magnetic composite film

A magnetic structure having improved permeability characteristics at very high frequencies and comprising a plurality of magnetic metal layers, together with electrically insulating layers which are interposed between successive magnetic metal layers to form a laminate therewith, and at least one conductive strip electrically connecting together at least two of the magnetic metal layers, the conductive strip being of lesser width than the surface on which it is located, and serving to reduce eddy current losses.

Magnetic material having high permeability in the high frequency range

A method of manufacturing an amorphous alloy involves thermally treating or annealing the amorphous alloy material at a temperature lower than the crystallization temperature thereof through rotation of the alloy material relative to a magnetic field at a velocity so as to meet the following relationship:

Method of manufacturing an amorphous magnetic alloy

Annealing method for an amorphous magnetic alloy including the steps of preparing an amorphous magnetic alloy film, and annealing the amorphous magnetic alloy film at an elevated temperature lower than Curie temperature and crystallization temperature of the amorphous magnetic alloy film under an application of a repetition of alternately applied a first magnetic field and a second magnetic field, in which the first magnetic field is applied along one direction in a major surface of the amorphous magnetic alloy film for a predetermined period, and the second magnetic field is applied along a second direction perpendicular to the one direction in the major surface of the amorphous magnetic alloy film for the predetermined period.

Annealing method for amorphous magnetic alloy

A method of manufacturing an amorphous magnetic alloy having high permeability comprises the steps of:

The amorphous magnetic alloy ribbon for magnetostriction delay lines are prepared by annealing the ribbon having a negative magnetostriction constant at a temperature lower than the crystallization temperature of the alloy under a tension sufficiently enough to support the ribbon substantially straight between the both ends thereof. The ribbon thus prepared permits a decrease in a deviation in a distribution of internal stresses and the propagation speeds of magnetostriction vibration through the ribbon.

Method of manufacturing amorphous magnetic alloy ribbon and use for

A method of manufacturing a high permeability amorphous magnetic alloy is disclosed. In the method amorphous magnetic alloy ribbon prepared by quenching a melt of raw material is annealed at an elevated temperature lower than a crystallization temperature of the alloy, in a magnetic field. During the annealing, the alloy ribbon and the direction of the magnetic field are relatively rotated with each other. The method is especially useful to an amorphous magnetic alloy having high saturation magnetic induction where the magnetic Curie temperature of the alloy usually exceeds the crystallization temperature of the alloy.

A method of manufacturing an high permeability amorphous magnetic alloy is disclosed. In the method, an amorphous alloy ribbon is annealed at an elevated temperature T(.degree.K.) satisfying the relation 0.95.times.Tc (.degree.K.).ltoreq.T(.degree.K.)&lt;Tcry(.degree.K.) where Tc is a magnetic Curie temperature and Tcry is a crystallization temperature of the alloy. Then the ribbon is quenched to a room temperature from the elevated temperature. The quenched amorphous alloy ribbon is again annealed at a temperature between 100.degree. C. and 250.degree. C. By the method, the amorphous magnetic alloy shows a high permeability over a wide frequency range and flat frequency response characteristics of permeability over a wide frequency range.

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Kanagawa, Japan

Koichi Aso