JPH0673198B2 - Magneto-optical recording medium - Google Patents

Description

TECHNICAL FIELD The present invention relates to a recording medium used in a magneto-optical memory, and more specifically, a magnetic film having an easy axis of magnetization in a direction perpendicular to the film surface as a recording layer. The present invention relates to a magneto-optical recording medium in which information can be recorded by forming a reversed magnetic domain in a region irradiated with a light beam such as a laser and which can be read 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 direction perpendicular to the film surface with high recording sensitivity and no grain boundary noise. It is the most promising because it has advantages such as easy production of a film having properties.

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. The erasing is performed by so-called batch erasing, in which an external magnetic field is applied with a polarity opposite to that used during recording, and a laser light beam is uniformly irradiated onto the recording medium at the same intensity as during recording.
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 unit is essential in addition to the optical system for generating the laser light beam. The structure of the magneto-optical recording / reproducing device tends to be complicated. Further, air core coils, electromagnets, permanent magnets and the like have been conventionally used as the external magnetic field applying means, but it is difficult to use these to switch a magnetic field of several hundred Oersted order at high speed. Therefore, the above-mentioned batch erasing method is used for erasing, and recording is
A method of modulating the laser power at high speed in a constant magnetic field has been used.

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, which is made of a conductor and has a constant interval over almost the entire surface of a card-shaped substrate. Zigzag pattern is formed by folding back in the width direction of, and then in the direction perpendicular to the film surface,
A recording layer having magnetic anisotropy and made of an amorphous magnetic alloy film,
It is characterized in that a protective layer made of a dielectric material is formed in this order.

(Function) A bias magnetic field is applied in a vertical direction to the recording layer portion formed between the patterns by applying a current to a zigzag pattern formed of a conductor formed on a substrate and having a constant interval. It The bias magnetic field application direction can be easily switched by switching the direction of current flow. 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. Over almost the entire surface of the card-shaped glass substrate 1, Au folded in the width direction and
The zigzag pattern 2 made of a conductor such as Al has a height of about
It is formed with 3000 Å, width of about 4000, Å pitch of about 1 μm, and has a magnetic anisotropy in the direction perpendicular to the film surface, and a recording layer 3 made of an amorphous magnetic synthetic film with a thickness of 3000 Å Tb. , Fe, Co
An alloy film (Tb _0.22 (Fe _0.9 Co _0.01 ) _0.78 ) and a Si ₃ N ₄ film having a refractive index of 2.0 and a thickness of 800 Å are formed in this order as the protective layer 4.

Each layer is formed by magnetron sputtering. First,
The folded pattern 2 made of a conductor such as Au is formed as follows. 30 Au film on card-shaped glass substrate 1
After spattering to a thickness of 00Å, as shown in Fig. 3 (a), a resist pattern 5 having a thickness of 2000Å and a width of 5000Å is set to 1 µm.
Formed at m pitch, and using Ar, gas pressure 2.6 × 10 ^-2 Pa 4
Ion mill for minutes. Further, by removing the remaining resist by oxygen plasma, FIG.
As shown in, the Au folded pattern 2 has a height of 3000
Å, width 4000 Å, pitch about 1 μm.

The TbFeCo alloy film forming the recording layer 3 is formed on the FeCo target,
Using a composite target with Tb pieces arranged, in an Ar gas atmosphere,
It is manufactured with a power density of 4 w / cm ² and a sputtering gas pressure of 3.5 × 10 ^-1 Pa.

The Si ₃ N ₄ film forming the protective layer 4 uses a Si target and Ar and N
_The power density was 8 w / cm ² and the sputtering gas pressure was 2.5 by reactive sputtering using a mixed gas of ₂ (45.5% N ₂ ) as the sputtering gas.
Manufactured at × 10 ^-1 Pa.

Next, the recording operation using the magneto-optical recording medium according to the present invention will be described.
This will be described with reference to FIGS. 1 and 4. By passing a current between the conductor terminals A and B, a magnetic field 6 shown by a broken line is generated around the folded pattern 2, and a vertical bias magnetic field is applied to the recording layer portion formed between these patterns. be able to. The application direction and magnitude of this 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, as shown in FIG. 4, the laser beam 8 is moved relative to the card-shaped magneto-optical recording medium to irradiate a desired recording layer portion between the folded patterns 2 and the temperature of the recording layer 3 is changed. The desired recording magnetization 7 is realized in the cooling process of the recording layer 3 by switching the current flowing between the conductor terminals A and B in synchronization with the magnetization timing while increasing the temperature above the Curie temperature (220 ° C). can do. 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 like are not limited to those described above, and are appropriately selected according to the desired recording density of the recording medium and the magnitude of the bias magnetic field. . The height of the pattern is preferably tens of millions of angstroms, and the pitch is preferably around 1 μm. As a protective layer made of a dielectric material, in addition to Si ₃ N ₄ , AI
N, which was formed SiO _2, SiO or the like to a thickness of several hundred to several thousand Å 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 conductor pattern built in the medium.

[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 ... Folded pattern made of conductor, 3 ... Recording layer, 4 ... Protective layer, 5 ... Resist pattern, 6 ... Magnetic field, 7 ... Magnetization, 8 ... It is a laser beam.

Claims (1)

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