A master information carrier comprises a substrate whose surface has an embossed pattern corresponding to an information signal. At least a surface of the protruding portion of the embossed pattern is made of a ferromagnetic material. A method for writing an information signal into a sheet or disk magnetic record medium with a ferromagnetic thin film or coating is performed by putting the surface of the magnetic record medium into contact with the master information carrier so as to write a magnetized pattern corresponding to the embossed pattern of the master information carrier into the magnetic record medium.

Master information carrier, process for producing the carrier, and method and apparatus for recording master information signal on magnetic recording medium by using the carrier

A magnetic sensor element 1 includes a substrate 10, a conductive layer 12 of a conductive material, and a magnetic layer 11 of a magnetic material, which encloses the conductive layer 12. AC is applied to the element from a drive power source 50, and a detector 60 detects an impedance change due to an external magnetic field. The magnetic layer 11 is bestowed with magnetic anisotropy in a direction orthogonal to the direction of energization of the element 1. With the provision of the conductive layer 12 of conductive material and also with magnetic anisotropy imparted to the magnetic layer 1, the element 1 may be made a low resistivity element. A reactance change and a resistance change of the element due to an external magnetic field change, thus can be effectively detected in drive frequencies two orders of magnitude lower than in the case of a prior art magnetic sensor element. The magnetic anisotropy of the magnetic layer 11 is controlled to prevent magnetic field detection dynamic range variations with drive frequency.

Multilayered magnetic sensor having conductive layer within megnetic layer

A spin torque oscillation magnetoresistive sensor for measuring a magnetic field. The sensor uses a change in precessional oscillation frequency of a magnetization of a magnetic layer to determine the magnitude of a magnetic field. The sensor can include a magnetic free layer, a magnetic pinned layer and a non-magnetic layer sandwiched therebetween. Circuitry is connected with these layers to induce an electrical current through the layers. Spin polarization of electrons traveling through the device causes a spin torque induced precession of the magnetization of one or more of the layers. The frequency of this oscillation modulates in response to a magnetic field. The modulation of the oscillation frequency can be measured to detect the presence of the magnetic field, and determine its magnitude.

Spin Torque Oscillator Sensor

An apparatus for storing and reading a magneto-optical disk has a slit shaped aperture located in an air-bearing slider which flies above the disk. Domains of the disk are selected for storing or reading by a light beam. The domains are reduced in size without losing inter-domain resolution by illuminating the disk with the portion of a focused laser beam incident on the disk through the slit, the slit width being less than the full beam width. The slider preferably terminates a wedge-shaped cavity suspended above the medium a distance substantially less than the wavelength of the illuminating light; the thickness of the edges of the slit being substantially less than the wavelength of the illuminating light.

Method for increasing linear bit density in magneto-optical storage media

In a magnetic detecting element utilizing a magnetic impedance effect, a high-permeability magnetic film is formed on a non-magnetic substrate and has magnetic anisotropy in a predetermined direction in the plane of the magnetic film. A high-frequency current is applied across two points in a direction perpendicular to the direction of the magnetic anisotropy, and a change in impedance generated between the two points is converted into an electric signal to obtain an output.

Magnetic detecting element utilizing magnetic impedance effect

An optical recording device for forming recording tracks of an indented pattern on a magnetic recording tape comprises a rotary drum which has at least two windows, the magnetic recording tape being driven obliquely on the windows along an outer surface of the drum, and an optical system, disposed inside the rotary drum, for converting a modulated laser beam incident on the optical system into two slit beams, major axes of sections of which form a predetermined angle and for emitting the slit beams on the magnetic recording tape through the windows, whereby the recording tracks of the indented pattern in correspondence with the signal are formed obliquely on the magnetic recording tape with respect to a longitudinal direction of the magnetic recording tape by the slit beams so as to form different azimuths between adjacent recording tracks.

Optical magnetic recording device

A magnetic material (1b-2) whose high frequency characteristics vary in response to a signal field recorded on a magnetic recording medium (1) is provided as a magnetic layer in a high frequency coupling circuit including the magnetic recording medium (1) and a reproduction head (5). The coupling degree of the high frequency coupling circuit noticeably varies with the change of the high frequency characteristics of the magnetic material (1b-2), thereby enabling the reproduction of the recorded signal by utilizing the change of the high frequency characteristics.

Magnetic reproducing system

A magnetic playback apparatus using ferromagnetic resonance of a magnetic material provided with a magnetic anisotropy to develop an anisotropic magnetic field. The magnetic material is disposed at a position influenced by a magnetic field resulting from a signal recorded on the magnetic recording medium. The magnetic material is coupled with a high frequency circuit to be supplied with a high frequency magnetic field. The high frequency characteristics of the magnetic material greatly vary depending on a ferromagnetic resonance. A ferromagnetic resonance magnetic field is set up, allowing for the magnitude of an anisotropic magnetic field and the frequency of the high frequency magnetic field, so that a great variation in the high frequency characteristics due to the ferromagnetic resonance may be obtained according to the signal magnetic field.

Magnetic resonance-type playback apparatus including a magnetic material having magnetic anisotropy

A capacitance element includes as an interelectrode substance a magnetic body for detecting a magnetic field formed by a magnetic recording medium A tuned circuit includes the capacitance element as a tuning element and receives a signal from a high-frequency oscillator The magnetic characteristics of the magnetic body change with changes in the magnetic field formed by the magnetic recording medium The high-frequency signal output from the tuned circuit changes with changes in the magnetic characteristics of the magnetic body A detecting circuit detects the changes in the high-frequency signal output so as to reproduce signals recorded on the magnetic recording medium

Magnetic reproduction system utilizing magnetic body as capacitor

A capacitance element (10) includes as an interelectrode substance a magnetic body (11) for detecting a magnetic field formed by a magnetic recording medium (21). A tuned circuit (10, 14) includes the capacitance element as a tuning element and receives a signal from a high-frequency oscillator (16). The magnetic characteristics of the magnetic body change with changes in the magnetic field formed by the magnetic recording medium. The high-frequency signal output from the tuned circuit changes with changes in the magnetic characteristics of the magnetic body. A detecting circuit (20) detects the changes in the high-frequency signal output so as to reproduce signals recorded on the magnetic recording medium.

Norikazu Sawazaki

Papers

Optical magnetic recording device

Magnetic reproducing system

Magnetic resonance-type playback apparatus including a magnetic material having magnetic anisotropy

Magnetic reproduction system utilizing magnetic body as capacitor

Magnetic reproduction system