JPS63282943A - magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To obtain the title recording medium having satisfactory recording, reproducing, and erasing characteristics and capable of using any heat-resistant substrate by separating the magnetic layer of the magneto-optical recording medium into a magnetic layer exclusively used for reproducing and a magnetic layer exclusively used for recording. CONSTITUTION:At least one kind of Bi-contg. garnet such as 12Bi2O3.0.3Y2O3.0.6 Ga2O3.1.9Fe2O3 and Co-contg. ferrite such as Co.0.4Al2O3.0.6Fe2O3 is vapor- deposited on a soda-glass sheet 1 through an Ni-Zn ferrite substrate film 2 to form the reproducing magnetic layer 2. The recording magnetic layer 4 consisting of magnetic substance of magnetoplumbite hexagonal ferrite such as SrO.Al2O3.0.5Sc2O3.4[Fe2O3] with about Hc=0.5-5 kOe and Ms=5-50emu/ g and contg. a m.p. lowering material such as Sn, In2Te2, PbO, and Na2CO2 is then laminated, and a reflecting layer 5 of Cr, etc., is laminated to complete the medium. Since the magnetic layer is thus separated, the characteristics of the recording medium are improved, a heat-resistant substrate can be used, and the medium can be mass-produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magneto-optical recording medium in which a magnetic layer is separated into two different functions, one for reproduction and one for recording.

Prior Art The present inventor previously disclosed Japanese Patent Application Laid-open No. 59-45644 and No. 60-
No. 164302 proposed the use of magnetoplumbite hexagonal ferrite magnetic material in magneto-optical recording media. The magnetic material used here is one in which part of the Fe in the crystal is replaced with another metal in order to improve the recording, reproducing, or erasing characteristics of the magneto-optical recording medium. However, in order to improve the recording characteristics (recording sensitivity), some of the Fe was
.

If the Curie temperature is lowered by substituting Sc, Zn, etc., the coercive force Hc, which contributes to recording retention, will be significantly lowered, and in order to improve the erasing characteristics, some of the Fe may be replaced with A, Ga, Rh, etc.
, Cr, etc. to reduce the saturation magnetization Ms to an appropriate value, the magneto-optic effect (in this case, the Faraday rotation angle θF) that contributes to the reproduction characteristics is significantly reduced.

Therefore, it is difficult for the proposed magneto-optical recording medium to satisfy all of the recording, reproducing and erasing characteristics. Moreover, when producing the magnetic film of these recording media, the substrate temperature is kept at 550°C.
It is necessary to raise the temperature to a high temperature of .degree. C. or higher, and therefore only special heat-resistant substrates can be used.It is difficult to maintain the substrate at a high temperature and heat it uniformly, and mass production is also difficult.

Object The object of the present invention is to provide a magneto-optical recording medium that satisfies all recording, reproducing and erasing characteristics, expands the range of use of the substrate, and can be mass-produced.

Structure The magneto-optical recording medium of the present invention is a magneto-optical recording medium having a magnetic layer on a heat-resistant substrate, in which the magnetic layer is divided into two layers with different functions, one for reproduction and one for recording, and the magnetic layer for reproduction is made of Bi-containing iron. The recording magnetic layer is composed of at least one type of magnetic material such as garnet and Co-containing ferrite, and has a magnetoplumbite hexagonal ferrite magnetic material having a large He content and an appropriate Ms, and a melting point lowering effect on this magnetic material. It is characterized by containing a metal, a metal alloy, or a compound.

In this way, the magneto-optical recording medium of the present invention replaces the conventional magnetic layer with
A magnetic layer with a large θ for reproduction only, and a large He and appropriate Ms for recording (record retention and erasing) only.
The magnetic layer is separated into two layers with different functions. Note that either of these two layers may be located above or below the substrate.

The reproducing magnetic layer of the present invention is composed of at least one kind of magnetic material: Bi-containing garnet and Co-containing ferrite. Specific examples of these magnetic materials are shown below along with θ and values.

[Tsu-Cai Hoden Flea Liu Fu (A-1)
1.2Bi203-0.3Y20. -0.6Ga20
3-1.9F82032.0 (λ=633nm) (A-
2) Bi2O3・0.5Gd203-0.6A&03
・1.9Fe2031.5 (λ=6330m) (A-3
) Bi, 03・0.5DY203-COO-GeO□
-1,5Fe20. 1.0 (λ=633 nm) (A
-4) Bi2O3・0.5DY203-0.4In2
03・2.3Fe2031.5(λ=633nm)(A
-5) Co0/0.4A horse 03/0.6Fe2032.
0 (127800m) (A-6) CoO・O-6Mn
0 ・O-2GeO□+ o, 5Fe, o31.5 (
λ=7800m) (A-7) Co0・0.6Zn0・
0-2T102 ・O-5Fe2o31 , O(127
800m) (F8) Coo・O-6Rh203 ・0
．． 4Fe203 2.5 (127800m
) (A-9) CoO・0.6Cr203・0.4Fe2
032.0 (127800 m) Note that the reproducing magnetic layer is formed by depositing a target or sintered material having these compositions on the surface of a substrate or the like by sputtering or vapor deposition.

The thickness is usually about 0.1 to 1 μm.

On the other hand, the recording magnetic layer of the present invention includes a magnetoplumbite hexagonal ferrite magnetic material having a large Hc and an appropriate Ms, and a metal, metal alloy or oxide, carbonate, etc. that has a melting point lowering effect on this magnetic material. It consists of a system containing the following compounds. Here, He of the feratomagnetic material is 0.
5 to 5 KOe is preferable, and Ms is 5 to 50 emu/
g is preferred. Specific examples of magnetoplumbite hexagonal ferrite compositions having such characteristics are shown below along with Hc values and Ms values.

Replacement Composition □Ms (esu/g) (1) S■・A
Horse 03.0. Key 03.4 (F also 03) 2
15(2) BaO-A horse・0.5In203・4
[Fe2O3]215(3)BaO・1.5A horse 03・
SnO2・ZnO・4[Fe2O3]415(4) S
rO・1.5Ga20.・0.5Sc20.・3.5 [
Fe2O,) 2 25(5) BaO-1
,5Cr203・0.5In203・3.5[Fe2O
,) 1.0 30Hα peek → melt (esu/g) (6) SrO・1.5A horse 03・0.5Tmo 0・0.5
Zn20・3.5[Fe2O3]4.020(7)Ba
O・1.5Rh203・0.5Sb203-4.0[F
e2O,] 4.0 25(8) Ba
O・ALO,・0.5Ti02・0.5Zn03.5(
Fe20. ) 2.0 20 Specific examples of metals, metal alloys, or compounds that have a melting point lowering effect on these ferrite magnetic materials include Sn, Pb, Si,
In2Te2. Sb2Te3゜Bi2Te3. Ga
Sb, InSb, PbO, PbF2゜Na2CO3,B
Examples include i2O3, P2O, H3BO3, NaCO3, and mixtures thereof. Further, specific examples of the sintered material and target used for the recording magnetic layer include the following.

Harvesting composition (B-1) SrO・ALO3-0,5SC203-4(
Fe20. )-PbO(B-2)BaO-A%03.0
．． 5In203・4(Fe20.)・PbO・PbF2
(B-3) Ba04.5A403・SnO□・Zn0・
4(Fe203:l ・Na2Co3(B-4)Srf
)1.5Ga203・0.5Sc203・3.5(Fe
203)・Bi203(B-5) Ba0・1.5Cr
203-0.5In203-3.5 (Fe203) -
p2o, -H3BO3(B-6)SrO-1,51,
03-0,5Te20-0.5Zn20-3.5(Fe
203)・Bi203(B-7)BaO-1,5Rh2
03・0.5Sb203-4.0(Fe203:l-B
i203 (B-8) BaO・A bird 03・0.5Ti20
3・0.5Sc203・3.5[Fe2O3]・P2O
5.NaCO3 The recording magnetic layer is formed by depositing a sintered product or a target having these compositions on a substrate by sputtering, vapor deposition, or other methods. Thickness is usually 0.1~
It is about 1 μm.

As the substrate, ordinary glass such as soda glass, lead glass, borosilicate glass, quartz glass, aluminosilicate glass, crystallized glass (product name: Milacron PH-3, Milacron PC-1, Milacron PP-1, Milacron P) can be used.
H-1); Ceramic, e.g. alumina, MgO, Ba
O.

AQN, PLZT; single crystal, such as silicon, GGG,
Lithium tantalate, sapphire, MgO; metal plate (
Examples include alumite, aluminum, stainless steel, and duralumin; plastic plates such as polyamideimide, polyimide, aramid, polyketoneimide, polybiphenylimide, and polypyromellitic acid imide.

In the magneto-optical recording medium of the present invention, in order to improve the crystal orientation of each magnetic layer for reproduction and recording, an underlayer is provided between the substrate and the magnetic layer, and a magnetic layer is provided to protect the surface of the recording medium. A protective layer is provided on the magnetic layer, or a reflective layer is provided on the magnetic layer to perform reproduction using the Faraday effect of the magnetic layer (
However, in this case, use a translucent substrate)
A dielectric layer may be provided between the magnetic layer and the reflective layer to increase the Faraday rotation angle and improve reproduction output, or a dielectric layer may be provided between the substrate and the magnetic layer to reduce loss of laser output due to heat conduction during recording and erasing. A heat insulating layer can be provided between the layers or the reflective layer. In addition, to ensure error-free recording, reproduction, and erasing of the magneto-optical recording medium, a separate guide is provided on the substrate, underlayer, magnetic layer, reflective layer, heat insulating layer, induction layer, or protective layer itself, or on the substrate or the above layer. A track can be provided.

Examples of the structure of the magneto-optical recording medium as described above are shown in FIGS. 1 to 3. That is, the magneto-optical recording medium shown in FIG. 1 has an underlayer 2, a magnetic layer for reproducing 3, a magnetic layer for recording 4, and a reflective layer 5 provided in this order on a substrate 1. The magneto-optical recording medium shown in FIG. 2 includes a substrate 1, an underlayer 2, a recording magnetic layer 4, a reproducing magnetic layer 3, and a strip-shaped guide track 6.
and a protective layer 7 are sequentially provided. The recording medium shown in FIG. 3 has a base M2, a reproducing magnetic layer 3, a recording magnetic layer 4 with groove-shaped guide tracks 6', a reflective layer 5, and a protective layer 7 provided on the substrate 1 in this order.

Here, the material of the underlayer is a soft magnetic material, such as Ni-Z.
n ferrite, Co-Zn ferrite, M n -Z
n ferrite, M g -Z n ferrite; dielectric, e.g. S i O, S j02 + S 13
N4 +MgO, Tie2. ZnO, Af1203. T
Examples include he2. Appropriate thickness is about 0.1 to 1 μm.

Materials for the protective layer include the aforementioned derivatives; resins used for substrates such as imide resins, acrylic resins, styrene resins, epoxy resins, phenol resins, polyurethane resins, polycarbonate resins, polyamide resins, and polyethersulfone resins. etc. Thickness is 0.
Approximately 1 to 10 μm is appropriate.

The material for the reflective layer is metal, such as Cr or Ni.

Au, AQ, Ag, Rh, Pt, Cu, Pd.

Nd, Cot Fe; metal nitride, e.g. T a N
.

Examples include TsN and CrN. Thickness is 0.1-0.5
Approximately μm is appropriate.

Examples of the material for the heat insulating layer include the above-mentioned derivatives. Appropriate thickness is about 0.1 to 1 μm.

As a method for forming each layer as described above, in the case of an inorganic material, a method such as vapor deposition or sputtering is usually adopted, and in the case of an organic material, a coating method (spin code method) is usually adopted.

The present invention will be explained below by way of examples.

Example 1 Ni-Zn ferrite was sputtered on a soda glass substrate at a substrate temperature of 200°C to form a base layer with a thickness of 0.2 μm, and the sintered body of A-1 and the B- The sintered body of No. 1 was sequentially sputtered at a substrate temperature of 450°C to form a magnetic layer with a thickness of 0.5 μm and a magnetic layer with a thickness of 0.2 μm.
After forming a thick recording magnetic layer, a 0.1 μm thick reflective layer was formed thereon by sputtering PT at a substrate temperature of 400° C., thereby producing a magneto-optical disk of the type shown in FIG.

Example 2 Zn○ was sputtered on a Pyrex (borosilicate) glass substrate at a substrate temperature of 300°C to form a 0.1 μm thick base layer, and the sintered body of B-2 and the A
The sintered body No.-2 was sequentially sputtered at a substrate temperature of 450° C. to form a magnetic layer for recording with a thickness of 0.2 μm and a magnetic layer for reproduction with a thickness of 0.5 μm, respectively. Next, a Cr film with a thickness of 0.1 μm was formed on this magnetic layer for reproduction by a vapor deposition method, and an ultraviolet curable resin film was further formed on it by a spin code method. A mask having a band-shaped (groove-shaped guide) Cr pattern with a track pitch of 1.8 μm and a track pitch of 1.8 μm was closely attached, the entire surface was exposed from above, the resin film was partially removed with a solvent, and the exposed Cr film was sputter etched. A magneto-optical disk of the type shown in Fig. 2 was created by forming a guide track consisting of a band-shaped Cr pattern on the reproducing magnetic layer, and then spin-coding silicone resin to form a 5 μm thick protective layer. Had made.

Example 3 After forming a base layer by depositing Co-Zn ferrite on a polybiphenylimide substrate at a substrate temperature of 300°C, the sintered body of A-6 and the sintered body of B-3 were placed on the substrate. A magnetic layer for reproduction and a magnetic layer for recording, each having a thickness of 0.5 μm and 0.2 μm, were formed by successive deposition at a temperature of 400° C. Next, a resin film was formed by spin-coding an ultraviolet curable resin on this recording magnetic layer, and this was covered with the strip-shaped Cr film used in Example 2.
After applying a patterned mask and exposing the entire surface to light, the resin film is partially removed with a solvent, and the exposed recording magnetic layer is etched to form groove-shaped guide tracks in the magnetic layer itself. , Au and SiO on it
A magneto-optical disk of the type shown in FIG. 3 was fabricated by sequentially depositing 2 and 3 layers at a substrate temperature of 400 DEG C. to form a reflective layer of 0.1 .mu.m thick and a protective layer of 1 .mu.m thick, respectively.

Example 4 A-3 is used instead of A-1, and B-1 is used instead of B-1.
A magneto-optical disk of the type shown in FIG. 1 was manufactured in the same manner as in Example 1, except that 4 was used.

Example 5 B-5 is used instead of B-2, and A-2 is used instead of A-2.
A magneto-optical disk of the type shown in FIG. 2 was manufactured in the same manner as in Example 2, except that 4 was used.

Example 6 A-5 is used instead of A-6, and B-3 is used instead of B-3.
A magneto-optical disk of the type shown in FIG. 3 was manufactured in the same manner as in Example 3 except that 6 was used.

Example 7 A-7 is used instead of A-1, and B-1 is used instead of B-1.
A magneto-optical disk of the type shown in FIG. 1 was manufactured in the same manner as in Example 1, except that Example 7 was used.

Example 8 A-8 is used instead of A-1, and 13B is used instead of B-1.
A magneto-optical disk of the type shown in FIG. 1 was produced in the same manner as in Example 1 except that -8 was used.

Example 9 B-1 was used instead of B-2, A-9 was used instead of A-2, and the base layer was made of Ni-Zn ferrite with a thickness of 0.2 μm.
A magneto-optical disk of the type shown in FIG. 2 was manufactured in the same manner as in Example 2, except that it was formed thicker.

Next, recording, reproduction, and erasing were performed on the above nine types of magneto-optical disks under the following conditions.

Recording conditions Light source: Semiconductor laser with dual wavelengths of 780 nm and output of 15 mW on the disk surface Light speed: 5 m/s Duty: 50% Recording magnetic field: 2000e Reproduction conditions Light source: Semiconductor laser with a wavelength of 780 and an output of 4 mW on the disk surface Light speed: Recording conditions Same erasing conditions Light source: Same linear velocity as recording conditions: Same duty as recording conditions: Same erasing magnetic field as recording conditions: 10000e (however, the direction of the magnetic field is opposite to that during recording) As a result, when recording, the bits are recorded at approximately 2 μm. , C/N
A signal of =40 to 45 dB was obtained. Also, when erasing, the records are completely erased.

Effects As described above, the magneto-optical recording medium of the present invention separates the conventional magnetic layer into a read-only magnetic layer and a recording-only magnetic layer.
In addition to satisfying all the recording, reproducing and erasing characteristics, it has the advantage of being able to use any heat-resistant substrate and being easy to mass produce.

[Brief explanation of the drawing]

FIGS. 1 to 3 are block diagrams of an example of the magneto-optical recording medium of the present invention. 1...Heat-resistant substrate 2...Underlayer 3...Magnetic layer for reproduction 4...Magnetic layer for recording 5...Reflection layer 6
...Band-shaped guide track 6'...Groove-shaped guide track 7...Protective layer

Claims (1)

[Claims] 1. In a magneto-optical recording medium having a magnetic layer on a substrate,
The magnetic layer is divided into two layers with different functions, one for reproduction and one for recording.The magnetic layer for reproduction is composed of at least one kind of magnetic material such as Bi-containing iron garnet and Co-containing ferrite, and the recording magnetic layer is composed of a A magneto-optical device characterized by containing a magnetoplumbite hexagonal ferrite magnetic material having a large magnetic force and appropriate saturation magnetization, and a metal, metal alloy, or compound that has a melting point lowering effect on the magnetic material. recoding media.