JPH0673200B2 - Magneto-optical recording medium - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a recording medium used in a magneto-optical memory, and more specifically, a magnetic layer having a magnetic easy axis in a direction perpendicular to the film surface of the recording layer. Further, the present invention relates to a magneto-optical recording medium capable of recording information by forming a reversed magnetic domain in a region irradiated with a light beam such as a laser and capable of reading by utilizing a magneto-optical effect.

(Prior Art) An optical memory attracts attention as one of large-capacity file memories. Among them, the magneto-optical memory has the advantage that the recorded information can be rewritten, and is therefore actively studied in various places. The recording medium is Tb, Gd, D
Amorphous magnetic thin films prepared by combining rare earth metals such as y and Ho and transition metals such as Fe, Co and Ni are magnetically anisotropic in the perpendicular direction to the film surface with high recording sensitivity and no grain boundary noise. Since it has the advantage that a film with properties can be easily made,
Most promising.

Conventionally, recording / erasing of information on such a recording medium is performed as follows. Recording is performed by irradiating a recording medium magnetized in one direction with a laser light beam to change the medium temperature to the Curie temperature Tc.
Alternatively, it is performed by increasing the temperature above the compensation temperature Tcomp and forming an inverted magnetic domain by an externally applied magnetic field and a demagnetizing field of the recording medium. For the disappearance, an external magnetic field is applied in the opposite pole to that at the time of recording, and the laser light beam is uniformly irradiated on the recording medium with the same intensity as that at the time of recording. This is done by so-called batch erase. As a result, the magnetization state of the recording medium returns to the initial state before recording.

(Problems to be Solved by the Invention) As described above, when recording is performed on the conventional magneto-optical recording medium, the external magnetic field applying means is indispensable in addition to the optical system for generating the laser light beam. Therefore, the structure of the magneto-optical recording / reproducing apparatus tends to be complicated. Further, conventionally, an air-core coil, an electromagnet, a permanent magnet, or the like has been used as the external magnetic field applying means, but it is difficult to switch a magnetic field of several hundred Oersted order at high speed using these. Therefore, the above-mentioned collective erasing method is used for erasing, and the method of modulating the laser power at high speed in a constant magnetic field is used for recording.

It is an object of the present invention to provide a magneto-optical recording medium capable of recording without the conventional external magnetic field applying means.

(Means for Solving the Problems) The magneto-optical recording medium of the present invention is an optical card recording medium, in which a high magnetic permeability magnetic layer and an insulating layer are formed in this order on a card-shaped substrate. A zigzag pattern formed of conductors is formed over almost the entire surface at regular intervals and has a zigzag pattern that descends in the width direction of the substrate, and then has magnetic anisotropy in the direction perpendicular to the film surface and is amorphous. It is characterized in that a recording layer made of a magnetic alloy film and a protective layer made of a dielectric are formed in this order.

(Operation) A zigzag pattern made of a conductor, which is formed on the substrate via a high-permeability magnetic layer and an insulator layer, is formed between the patterns by passing a current in a zigsag pattern. A bias magnetic field is applied to the recording layer portion in the vertical direction. The high magnetic susceptibility magnetic layer functions to efficiently guide the bias magnetic field to the recording layer portion. The bias magnetic field application direction can be easily switched by switching the current direction. Therefore, desired recording can be performed by switching the bias magnetic field while irradiating a constant laser power.

(Example) Next, the Example of this invention is described in detail using drawing. FIG. 1 shows an embodiment of a magneto-optical recording medium according to the present invention. FIG. 2 is a sectional configuration diagram. A 1000 Å-thick high-permeability magnetic layer 2 made of a NiFe alloy such as permalloy and a 500 Å-thick insulator layer 3 made of a SiN film are formed on a card-shaped glass substrate 1, and almost all over the layer. The zigsag pattern 4 made of conductor such as Au or Al folded back in the width direction has a height of about 3000Å, a width of about 4000Å and a pitch of about 1 μm.
And further has a magnetic anisotropy in the direction perpendicular to the film surface, and as a recording layer 5 made of an amorphous magnetic alloy film,
3000 Å thick TbFeCo alloy film (Tb _0.22 (Fe _0.9 C
o _0.1 ) _0.78 ), and as a protective layer 6, a refractive index 2.0 thickness 8
It is formed in the order of 00Å SiN film.

Each layer is formed by magnetron sputtering. First, the zigzag pattern made of a conductor such as Au is formed as follows. On a card-shaped glass substrate, a thickness of 10
00Å NiFe alloy film, 500Å thickness SiN film, 3000Å thickness Au
After forming the film in order, as shown in FIG.
A resist pattern 7 having a width of 00 Å and a width of 5000 Å is formed at a pitch of 1 μm, and ion milling is performed using Ar for a gas pressure of 2.6 × 10 ⁻² Pa for 4 minutes. Further, by peeling off the resist remaining by the oxygen plasma, the folded pattern 4 of Au has a height of 3000 Å and a width of 40 mm as shown in FIG. 3 (b).
It is formed with a pitch of about 1 μm. TbFeCo forming the recording layer
The alloy film is produced by using a composite target in which Tb pieces are arranged on a FeCo target in an Ar gas atmosphere with a power density of 4 W / cm ² and a sputtering gas pressure of 3.5 × 10 ^-1 Pa.

Next, a recording operation using the magneto-optical recording medium according to the present invention will be described with reference to FIGS. Conductor terminals A, B
By passing a current between them, a magnetic field 8 shown by a broken line is generated around the zigzag pattern, and a bias magnetic field can be applied in the vertical direction to the recording layer portion formed between these patterns. The direction and magnitude of the bias magnetic field can be easily selected depending on the direction and magnitude of the current flowing between the conductor terminals A and B. Therefore, the fourth
As shown in the figure, the laser beam 10 is moved relative to the card-shaped magneto-optical recording medium, and the desired recording layer portion between the folded patterns is irradiated, and the temperature of the recording layer is equal to or higher than the Curie temperature ( The desired recording magnetization 9 can be realized during the cooling process of the recording layer by switching the current flowing between the conductor terminals A and B in synchronization with the magnetization timing while increasing the temperature to 220 ° C.). . The current value is appropriately selected within the range of several tens to several hundreds of milliamperes depending on the film composition of the recording layer.

Here, the shape such as the height and pitch of the conductor pattern, the number of turns, and the thickness of the high-permeability magnetic layer are not limited to those described above, but the recording sensitivity and the bias magnetic field of a desired recording medium are not limited. It is appropriately selected according to the size of. The height of the pattern is preferably several thousand angstroms, and the pitch is preferably around 1 μm. As the protective layer and the insulating layer made of a dielectric material, a layer in which AlN, SiO ₂ , SiO or the like is formed in a thickness of several hundred to several thousand liters in addition to SiN is used.

(Effects of the Invention) As described above, according to the present invention, it is possible to provide a novel card-shaped magneto-optical recording medium in which the bias magnetic field can be controlled by the current flowing in the folded pattern built in the medium.
Further, the high magnetic permeability magnetic layer provided between the substrate and the conductor pattern via the insulating layer has a function of efficiently guiding the bias magnetic field to the recording region.

[Brief description of drawings]

1 and 2 are diagrams showing an embodiment of the present invention, FIG. 3 is a diagram showing a manufacturing method of the present invention, and FIG. 4 is a diagram explaining an operation of the present invention. In the figure, 1 ... Substrate, 2 ... High-permeability magnetic layer, 3 ...
... Insulating layer, 4 ... Folded pattern made of conductor,
5 ... recording layer, 6 ... protective layer, 7 ... resist pattern, 8 ... magnetic field, 9 ... magnetization, 10 ... laser beam.

Claims (1)

[Claims] 1. An optical card recording medium, wherein a high magnetic permeability magnetic layer and an insulating layer are formed in this order on a card-shaped substrate,
A zigsag-like pattern formed of a conductor and having a constant interval and folded back in the width direction of the substrate is formed over almost the entire surface, and then has a magnetic anisotropy in the direction perpendicular to the film surface.
A magneto-optical recording medium comprising a recording layer made of an amorphous magnetic alloy film and a protective layer made of a dielectric material in this order.