JPH0719400B2 - Magneto-optical recording medium - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magneto-optical recording medium used in hard disks, floppy disks, magneto-optical memories and the like.

2. Description of the Related Art Conventionally, a magnetic recording medium using a hexagonal oxide is known as a magnetic material. Magnetic recording media using these hexagonal oxide magnetic materials include, for example, hexagonal plate-like powder particles of Ba ferrite dispersed in a binder and applied on a support, and magnetic field orientation is performed to form a perpendicular magnetization orientation film. Was being created. The recording density of the recording medium obtained in this case is about 76 KBI, and it is necessary to make the particle size of the Ba ferrite hexagonal plate-like powder smaller in order to perform higher density recording. However, when the particle size becomes small, the axial ratio between the plane direction and the layer direction becomes small, and it becomes difficult to orient the magnetic field. In addition, since there is a non-magnetic binder in the oriented hexagonal plate-shaped gap, the recording density is reduced by this area. According to the present invention, a hexagonal W-type oxide magnetic thin film is directly formed on a substrate by a sputtering method, a vapor deposition method, or an ion plating method without using a binder to obtain a high-density magneto-optical recording medium having no nonmagnetic region. To do. The hexagonal W-type oxide magnetic material has a high Curie temperature and cannot be recorded by a semiconductor laser. Therefore, a part of Fe was replaced with another metal to lower the Curie temperature and applied to a magneto-optical recording medium.

An object of the present invention is to provide a magnetic recording medium capable of high-density recording, and a magneto-optical recording medium having a constitution which solves the above problems when the conventional hexagonal oxide magnetic material is used. It is what

Structure The present invention has the general formula ▲ A Me ²⁺ ₂ ▼ [MxFe _16- x] O ₂₇ (where A is B
a, Sr, Pb, Ca 1 type, Me ²⁺ is Fe, Zn, Ni, Mg, Co, Cu 1 or 2 types, M is Al, Ga, Cr, In, Ti 1 or 2 types , O <X ≦
5) A magneto-optical recording medium having a perpendicular magnetization film of a hexagonal W-type oxide magnetic material. The hexagonal W-type oxide magnetic material of the present invention has a structure similar to the magnetoplumbite type, O ²⁻
The hexagonal type cations are densely packed with cations, and the cations intervene in the O ² − interstices. It is a perpendicular magnetized magnetic material suitable for magneto-optical recording media because it has a saturation magnetization 10% larger than that of the McNett Plumbite type and has magnetic anisotropy perpendicular to the film surface.

Specific examples include the following.

▲ SrFe ²⁺ ₂ ▼ 〔▲ Al ³⁺ ₄ ▼ Fe ₁₂ 〕 O ₂₇ , SrCo ²⁺ Fe ²⁺ 〔▲ Al ³⁺
₂ ▼ ▲ Fe ³⁺ ₁₄ ▼] O ₂₇ , SrZn ²⁺ Fe ²⁺ 〔▲ Al ³⁺ ₃ ▼ ▲ Fe
³⁺ ₁₃ ▼] O ₂₇ , ▲ BaZn ²⁺ ₂ ▼ 〔▲ Al ³⁺ ₂ ▼ ▲ Fe ³⁺ ₁₄ ▼〕 O ₂₇ , ▲ SrZn ²⁺ ₂ ▼
(▲ Al ³⁺ ₄ ▼ ▲ Fe ³⁺ ₁₂ ▼) O ₂₇ , ▲ PbZn ²⁺ ₂ ▼ (Sc ³⁺ ▲ Fe ³⁺ ₁₅ ▼) O ₂₇ , ▲ BaZn ²⁺ ₂ ▼ (▲ Ga
³⁺ ₃ ▼ ▲ Fe ³⁺ ₁₃ ▼] O ₂₇ , ▲ BaZn ²⁺ ₂ ▼ 〔In ³⁺ ▲ Fe ³⁺ ₁₅ ▼〕 O ₂₇ , ▲ SrZn ²⁺ ₂ ▼ 〔▲ Ga
³⁺ ₃ ▼ ▲ Fe ³⁺ ₁₃ ▼] O ₂₇ , ▲ BaCu ²⁺ ₂ ▼ 〔▲ Al ³⁺ ₃ ▼ ▲ Fe ³⁺ ₁₃ ▼〕 O ₂₇ , BaNi ²⁺ Cu ²⁺ 〔▲ Ga ³⁺ ₃ ▼ ▲ Fe ³⁺ ₁₃ ▼] O ₂₇ , ▲ SrCu ²⁺ ₂ ▼ 〔▲ Al ³⁺ ₃ ▼ In ³⁺ ▲ Fe ³⁺ ₁₃ ▼〕 O ₂₇ , ▲ BaFe ²⁺ ₂ ▼ 〔▲ Al ³⁺ ₃ ▼ ▲ Fe ³⁺ ₁₃ ▼] O ₂₇ , BaZn ²⁺ Fe ²⁺ 〔▲ Ga ³⁺ ₂ ▼ In ³⁺ ▲ Fe ³⁺ ₁₃ ▼〕 O ₂₇ , ▲ SrFe ²⁺ ₂ ▼ 〔▲ Ga ³⁺ ₃ ▼ ▲ Fe ³⁺ ₁₂ ▼] O ₂₇ , ▲ PbFe ²⁺ ₂ ▼ 〔▲ Ga ³⁺ ₃ ▼ In ³⁺ ▲ Fe ³⁺ ₁₂ ▼〕 O ₂₇ , ▲ SrCo ²⁺ ₂ ▼ 〔▲ Co ²⁺ ₃ ▼ Ti _{3 / 2} ▲ Fe ³⁺ ₁₂ ▼] O ₂₇ , ▲ PbFe ²⁺ ₂ ▼ 〔▲ Al ³⁺ ₂ ▼ ▲ Fe ³⁺ ₁₄ ▼〕 O ₂₇ , ▲ BaCo ²⁺ ₂ ▼ 〔Co ²⁺ Ti ⁴⁺ ▲ Fe ^{3 +} ₁₃ ▼] O ₂₇ , ▲ BaMg ²⁺ ₂ ▼ 〔▲ Al ³⁺ ₄ ▼ ▲ Fe ³⁺ ₁₂ ▼〕 O ₂₇ , ▲ SrZn ²⁺ ₂ ▼ 〔▲ Zn ²⁺ ₂ ▼ Sn ⁴⁺ ▲ Fe ³⁺ ₁₃ ▼] O ₂₇ , BiNi ²⁺ Fe ²⁺ (▲ Al ³⁺ ₃ ▼ ▲ Fe ³⁺ ₁₃ ▼) O ₂₇ , ▲ BaFe ²⁺ ₂ ▼
_{^{[▲ Cr 3+ 4 ▼ ▲ Fe 3+}} 12 ▼ ] O _27, ▲ BaZn ²⁺ ₂ ▼ _{^{[▲ Zn 2+ 2 ▼ Ta 4+ ▲}} Fe 3+ 13 ▼ ] O _27, ▲ BaFe ²⁺
₂ ▼ (▲ Bi ³⁺ ₃ ▼ ▲ Fe ³⁺ ₁₃ ▼) O ₂₇ , BaCo ²⁺ Fe ³⁺ (▲ Ga ²⁺ ₂ ▼ ▲ Fe ³⁺ ₁₄ ▼) O ₂₇ Hexagonal according to the present invention as described above The crystalline W-type oxide magnetic material is preliminarily used as a target, and the target is used to achieve a film thickness of 1000 by maintaining the temperature of the support at 200 to 650 ° C by means such as sputtering, ion plating, or ionization cluster beam method. Obtain a perpendicular magnetization film of ~ 30000Å.

The following is an example of the method for producing the target.
That is, powders of ACO ₃ and Fe ₂ O ₃ and MeO, MO were mixed in a pole mill for 50 hours, pressed into a mold, and O ₂ partial pressure was applied to this.
Baking is performed at 1200 to 1400 ° C. for 5 hours in a N ₂ gas flow of 10 ⁻⁶ to 10 ⁻¹² , 11 minutes. Next, this is crushed and crushed with a ball mill for 100 hours, and then this is acid-treated with a 5% HCl aqueous solution to remove impurities. This is dried, put in a mold, pressed, and fired at 1200 to 1400 ° C. in the atmosphere to obtain a desired hexagonal W-type oxide magnetic substance target.

As the support applicable to the present invention, heat-resistant glass, quartz glass, crystallized glass, GGG, lithium tantalate, single crystal Si, amorphous inorganic SiO ₂ , organic SiO ₂ , ceramic (ZnO, MgO, Al ₂ O ₃ , SiC, Si ₃ N ₄ , TiN, TaN, CrN, AlN), metal (Ni, Ni-P, stainless steel, copper, Al), heat-resistant plastic (polyimide, polyamide), etc. are preferable.

A perpendicular magnetization film of a hexagonal W-type oxide magnetic material is formed on these supports by a method such as the sputtering method described above. It should be noted that in order to form these magnetic substances epitaxially on the perpendicularly magnetized film, ZnO, AlN, Ti, BaFe ₂ O ₄ , M having a small misfit ratio at the interface with the hexagonal C-plane of the crystal of the W-type oxide magnetic substance.
It is preferable to provide an underlayer of nZnFe ₂ O ₄ , αFe ₂ O ₃ , MgO, MnFe ₂ O ₄ or the like.

The support may be provided with Al, Ag, Au, Pt, Cu or the like as a reflective layer, and such a reflective layer is suitable for use as a magneto-optical recording medium. In addition, if desired, an appropriate protective layer or protective plate may be provided on the upper surface of the magnetic layer. A soft magnetic layer such as Permalloy may be provided below the magnetic layer.

Examples will be shown below.

Example 1 ZnO having a film thickness of 500 Å was deposited as an underlayer 2 on a single crystal silicon (Hitachi Metals) support 1 and ▲ BaZn ²⁺ ₂ ▼ was deposited thereon.
[▲ Ga ³⁺ ₃ ▼ ▲ Fe ³⁺ ₁₃ ▼] 3000 Å the magnetic layer 3 made of O ₂₇
A polycarbonate plate having a thickness of 1 mm was bonded as a protective plate 4 via an epoxy adhesive layer 5 to obtain a magneto-optical recording medium as shown in FIG.

Example 2 On a Vycor glass 303 (made by Corning) support 1, Ag was deposited as a reflective layer 6 in a film thickness of 500Å, and then AlN was deposited as an underlayer 2 in a film thickness of 500Å, and a magnetic layer was formed on the underlayer 2. As SrZn ²⁺ Fe ²⁺ [▲ Al ³⁺ ₃ ▼ ▲ Fe ³⁺ ₁₃ ▼] O ₂₇ , a film thickness of 5000Å is adhered, and then a pregroove is formed on the magnetic layer 3 through an epoxy adhesive layer 5. A protective plate 4 made of a coated methyl methacrylate resin was joined to obtain a magneto-optical recording medium as shown in FIG.

Example 3 Zn was used as a base layer on the support 1 of Ni electroformed plate with pregroove.
O was deposited to a film thickness of 1000Å, and then BaZn ²⁺ F was used as the magnetic layer 3.
e ²⁺ [▲ Ga ³⁺ ₂ ▼ In ³⁺ ▲ Fe ³⁺ ₁₃ ▼] O ₂₇ is adhered to a film thickness of 3000Å, and a polymethylmethacryl resin is used as a protective plate 4 with an epoxy adhesive layer 5 on it. Bonding was performed to obtain a magneto-optical recording medium as shown in FIG.

Examples 4 and 5 In the magneto-optical recording medium shown in FIG. 1 obtained in Example 1, the optical recording was performed in the same manner except that the hexagonal W-type oxide magnetic material shown in the following table was used for the magnetic layer 3. A magnetic recording medium was obtained.

Examples 8 to 15 In the magneto-optical recording medium shown in FIG. 1 obtained in Example 1, the light was recorded in exactly the same manner as the magnetic layer 3 except that the hexagonal W-type oxide magnetic material shown in the following table was used. A magnetic recording medium was obtained.

Of the recording medium of each of the above examples, Examples 1, 2, 3, 8, 9, 10, 1
Curie temperatures of 1,12,13,14,15 are 350 ° C or lower, and recording / reproduction is performed by an optical laser.

Using the recording medium of Example 9 above, a laser beam of 830 nm was used.
A bit diameter of about 2μ was recorded as a result of recording at a frequency of 0.5 MHz while applying an external magnetic field of 300 aerial, which is the opposite of the magnetic field of the medium, to the intensity of mW. Then the same laser
When played back with a strength of 2 mW, the Faraday rotation angle was about 0.8.
The angle was ° / μm. Further, when the recording media of the respective examples shown in Table 1 and Table 2 were similarly tested, the obtained bit diameter was about 1 to 2 μm and the Faraday rotation angle was 0.2 to 0.9 ° / μm. .

Effects According to the present invention as described above, a hexagonal W-type oxide magnetic material is used as a target without using a binder, and this target is formed on a suitable support by sputtering, ion plating, ionization craft beam method, or the like. Since the epitaxial growth is performed, the perpendicular magnetic orientation is excellent and the recording density can be dramatically increased as compared with the conventional one.

[Brief description of drawings]

1 to 3 are schematic explanatory views showing the structure of a recording medium in an embodiment of the present invention. 1 ... Support, 2 ... Underlayer 3 ... Magnetic layer 4 ... Protective layer, protective plate, 5 ... Bonding layer 6 ... Reflective layer

Claims (1)

[Claims] 1. A general formula ▲ AMe ²⁺ ₂ ▼ [MxFe _16- x] O ₂₇ (where A is one of Ba, Sr, Pb and Ca, and Me ²⁺ is Fe, Zn, Ni, Mg, C).
1 or 2 of o, Cu, M is 1 or 2 of Al, Ga, Cr, In, Ti
A magneto-optical recording medium having a perpendicularly magnetized film of a hexagonal W-type oxide magnetic material represented by O <X ≦ 5).