JPS60218807A - Ferrimagnet material oxide and photomagnetic recording medium using it - Google Patents

Abstract

PURPOSE:To provide ferrimagnetic material oxide which allows recording and reproduction with laser beam by using such material as a magnetic recording medium which has a low curie temperature, resulting in no oxidation or corrosion and does not show deterioration of magnetic characteristics. CONSTITUTION:A photomagnetic recording medium, a ferrimagnetic material oxide indicated by the general expression, is formed by providing, on a transparent substrate, a vertical magnetic anisotropic magnetic thin film layer consisting of ferrimagnetic material oxide expressed by general expression and also providing a reflection layer on the magnetic thin film layer. It is also possible, as required, to provide a transparent dielectric layer between the magnetic thin film layer and reflection layer. The ferrimagnetic oxide forming such magnetic thin film layer has a low curie temperature and can be adapted to photomagnetic recording medium. Namely, a part of Fe is replaced with at least one M1 element in the general expression which has a small ion radius and can be easily replaced, in order to lower the curie temperature.

Description

[Detailed Description of the Invention] [Technical Field] The present invention provides an oxide seven-layer magnetic material with a low Curie temperature, no oxidation or corrosion, and no deterioration of magnetic properties, a transparent substrate, and perpendicular magnetic anisotropy. A magneto-optical recording medium comprising a magnetic thin film layer and a reflective layer, in which the perpendicular magnetic anisotropic magnetic thin film layer is made of the above-mentioned oxide ferrimagnetic material, and in which information can be recorded and reproduced using laser light. .

[Prior art]

Conventionally, it has been known to perform magneto-optical recording using a recording medium having an amorphous magnetic layer.

However, since amorphous magnetic layers are easily oxidized and the magneto-optical properties deteriorate when oxidized, it is necessary to provide a protective layer on top of the magnetic layer immediately after forming the magnetic layer. There are manufacturing difficulties because it is difficult to completely eliminate pinholes. Furthermore, since a large amount of oxygen remaining in vacuum during magnetic film fabrication is taken into the magnetic film layer, oxidation is promoted by light heat during recording, causing deterioration of magneto-optical characteristics. In addition, hexagonal M-type ferrite, which is a magnetic material that does not deteriorate due to oxidation, has been considered as a bubble material, but because this material has a high Curie temperature of over 450°C, it is not suitable for magneto-optical recording materials that can be recorded with laser light. Not applied.

〔the purpose〕

The present invention has been made in view of the above problems, and its purpose is to have a low Curie temperature, no oxidation or corrosion, no deterioration of magnetic properties, and to be able to be used as a recording medium at any time. An object of the present invention is to provide an oxide ferrimagnetic material that can be recorded and reproduced by light. Another object of the present invention is to provide a magneto-optical recording medium which has a low Curie temperature and is recordable by a semiconductor laser, using such an oxide Fe IJ ffl material.

〔composition〕

In order to achieve the above object, the oxide ferrimagnetic material of the present invention has the general formula % (%) (where Me is at least one element selected from the group consisting of Ba, Sr, and Pb). , Ml is at least one element selected from the group consisting of Ga and a, and h'
), Mn is Bi, 4, Th, Dy, Ho, Ia, Y
, co, Zn, T1, se.

■n, Sn, Oa, C! r, at least one element selected from the group consisting of Ni and Ge, 1<
x≦8, o<y≦6 and 1<X+7≦8, m is Ml
The magneto-optical recording medium according to the present invention is an oxide ferrimagnetic material having an ionic valence of MlH, and n is an ion valence of MlH. The magnetic thin film layer is composed of a perpendicularly magnetically anisotropic magnetic thin film layer made of an oxide Fe IJ ffl material, and a reflective layer provided on the magnetic thin film layer.

If necessary, a transparent dielectric layer may be provided between the magnetic thin film layer and the reflective layer.

Oxide Fe IJ constituting the magnetic thin film layer in the present invention
As for the magnetic material, we focused on the fact that the conventional general formula MeFe + 2019 type magnetic oxide (for example, Me is Ba, Sr, or PB) has a Curie temperature of 400°C or higher, which is too high to be applied to magneto-optical memory. This is an improved version with a much lower temperature so that it can be applied to magneto-optical recording media. That is, in the present invention, it is intended to lower the Curie temperature by substituting a part of Fe with at least one element of Ml in the above general formula, which has a small ionic radius and is easy to replace, that is, a or Ga, or both. has been done.

When Fe in MeFe, 20, q-type magnetic oxide is replaced with Ga or At, or both, its Curie temperature certainly decreases, but its coercive force (Hc) increases, making recording with laser light difficult. becomes. In order to eliminate this drawback, a part of the Fe of the magnetic oxide is further replaced with at least one element of Mn, namely Bi, Tb, .G+i,
Dy, Ho, La, Y, co, Zn, Ti, Sc,
Sn, Ca, In.

The purpose is to lower the coercive force (Hc) by substituting with Or, Ni, or Ge, and to improve the li&magnetic properties including the Faraday rotation angle and the magneto-optical properties of the magnetic oxide.

Here, the following 9 are representative examples of the oxide magnetic material of the present invention.

BaA#a, Fe, 019, SrA/j) a4.5
Fe5Cz g, BaA$a 2 Ge 5 Fe 6
01q, BaAbes, 7sFe60+v%PbA/
j) e 4.5Fe 5o 1 g, Ba At2G
a 5 Fe 70 + g, SrA/! f) e3.7
5Fe60+t, 5rLaGas, ysFe6ch
q %E3aGa5TbFe60 Ig, BaGa
3DyFe601 g, 5rGaTb5FeBO1 g,
BaGa3DyFe601, BaYGa4Fe70+
? , BaGa3BiFeaO,g,5rGa4Bi
2Fe6019, BaGa4Bi2Fll160+9,
BaGaj550oFe70. g, 5rGa4In2
Fe6019~BaGa3EfCJ8601g,B
aGa3ZnFe601 g, M, BaAυe3Fe
701g, PbAA) e sFe yo + r, E3rl'J
f) e5 Fe 701g, BaGa'3G (14F8
6.301g, BaGa3Bi2Fe701p, Ba
Ga4ZnFe 701g, SrG, a5Sn 1.
5Fe501g, SSrGa4Ti2F8601° Next, the present invention will be explained with reference to the drawings.

An example of the layer structure of the magneto-optical recording medium of the present invention is shown in FIG. 1, in which a magnetic thin film layer 2 is provided on a transparent substrate 1, and a reflective layer 3 is sequentially provided thereon. As the transparent substrate, quartz glass, Pyrex glass, etc. can be used. The magnetic thin film layer 2 is formed by depositing the above-mentioned oxidized Q'li+H substance of the present invention on the transparent substrate 1 by sputtering, vapor deposition, ion beam method, etc. to a film thickness of x, oooX to 1oo,
oooK -c[lReru.

As the reflective film layer 3, a metal film such as cu, g, ΔgX Au, 'pt, etc. or a nitride such as TiN, TaN, etc. is used, and is preferably formed to a thickness of about 200x to 5,000K.

Further, as shown in FIG. 2, a transparent dielectric layer 4 can be provided on the magnetic thin film 2 for the purpose of improving the magneto-optical characteristics, that is, increasing the Faraday rotation angle by an enhancement effect.

This transparent dielectric layer is made of 5i02, SiO, TiO2.
, Ti01Ce02, etc. are used.

In addition, as shown in FIG. 3, in order to protect the reflective film layer 3, plastic, TiN, 5i5N4, TaN
A protective film 6 made of SiO2, SiO, etc. can also be provided.

Furthermore, as shown in FIG. 3, the magneto-optical recording medium of the present invention may be provided with a guide layer 5 having guide grooves to guide laser light during recording and reproduction. This guide layer 5 is formed by sputtering a reflective film layer 3 on the uneven plastic plate obtained by applying TJ and V polymers on the magnetic thin film layer 2, pressing an uneven mold, and removing the mold after curing. Alternatively, it can be produced by laminating layers using a vapor deposition method.

〔Example〕

EXAMPLES The present invention will be explained in more detail below using Examples together with Comparative Examples, but the present invention is not limited to these Examples.

Example 1 510 particles were preliminarily deposited on a quartz glass substrate by sputtering.
2 to film thickness 1. oooX and BaA/J on top of it.
ll) Using a Luther Kerato with a composition of a4Fe70+ 9, the substrate temperature was 550°C, 0.3. mmTOrr
2 with an oxygen partial pressure of and a total gas pressure of 60 mm Torr.
Magnetic thin films with a thickness of 10,000× were deposited at a film formation rate of 5×/min. Next, further U is applied on top of this magnetic thin film.
The thickness of the reflective film is 1. oooX was laminated to produce a magneto-optical recording medium/I61 according to the present invention.

The Curie temperature of this magneto-optical recording medium was 210° C., the MS was 80 emu/cc, and the XHc was 4.5 KOe, which had good characteristics as a magneto-optical recording medium.

A magnetic field of l Q KOe perpendicular to the surface of this magneto-optical recording medium/I61 according to the present invention is applied to keep the direction of magnetization of the recording medium constant, and then While applying a magnetic field of 0.5 KOe, a semiconductor laser beam with an output of 10 mW and a wavelength of soo nm was emitted from the direction of the transparent substrate at a power of about 5 mW on the medium surface and a frequency of I MH.
When recording was performed on the recording medium by irradiating with a pulse of z and reversing the direction of the magnetic field of the recording medium, recorded bits with a bit diameter of about 1 s and an o o o 7y were obtained.

Example 2 Magneto-optical A according to the present invention was prepared in the same manner as in Example 1 except that SrAυa4Fe70+9 was used as the oxide magnetic material.
2 was produced. Curie temperature is 220℃, MS is 1t
) Oerou/cc', Hc is 4.0xoe, &,
It had excellent characteristics as a magneto-optical recording medium.

Example 3 A magneto-optical recording medium/I63 according to the present invention was produced in the same manner as in Example 1 except that 601 g of Baa2Ga3Fe was used as the oxide magnetic material. The temperature of cucumber is 220℃
, Ms is 10'Oemu/cc.

Hc was 4.0 KOe, which was an excellent property as a magneto-optical recording medium.

Example 4 A magneto-optical recording medium A4 according to the present invention was produced in the same manner as in Example 1 except that 601 g of BaGa4Bi2Fe was used as the oxide magnetic material. The temperature of cucumber is 200℃,
Ms is 50 emu/cc, Hc is 3. ,QKOe
It had excellent characteristics as a magneto-optical recording medium.

Example 5 A magneto-optical recording medium/16.5 according to the present invention was produced in the same manner as in Example I except that 5rGaaTbFe70+9 was used as the oxide magnetic material. The temperature of cucumber is 21
0℃, MS 7 Q emu/cc, Hc is 10.5
KOe, and had excellent characteristics as a magneto-optical recording medium.

Example 6 BaGa 4 DyFe 7019 as oxide magnetic material
A magneto-optical recording medium 46 according to the present invention was produced in the same manner as in Example 1 except that . The temperature of cucumber is 180
℃, Ms is 50 emu/cc, Hc is lKOe
It had excellent characteristics as a magneto-optical recording medium.

Example 7 A magneto-optical recording medium/I67 according to the present invention was produced in the same manner as in Example 1 except that BaGa3YFe BOI 9 was used as the oxide magnetic material. The temperature of cucumber is 210
℃, Me is 100 emu/cc, He is 3 KO
e, and had excellent characteristics as a magneto-optical recording medium.

Comparative Example An amorphous magnetic film having an atomic composition ratio of Tb/Fe-22/78 was formed on a glass substrate to a thickness of 3 by sputtering.
,00OL and then 510OL as a protective film on top of this.
A comparative magneto-optical recording medium was prepared by laminating the following materials with a film thickness of 2,000 mm.

Next, the magneto-optical recording media produced in Examples 1 to 7 and Comparative Example were heated at 70°C, 90% (RH) and 2
The presence or absence of oxidative deterioration after an accelerated storage test of 400 hours at 00° C. and normal humidity was determined for magnetic properties. The results are listed in the table below.

(Left below) Initial magneto-optical characteristics Accelerated storage test m (any6c) ) b (KOa) 道 (em4c)
Hc(KOs) Ms(e噌c) )b(KDe) Sir 1
11 80 4.5 80' 5.0 85 45/)
0 久0 /l)o ￥0 //)J' 41.0〃2
3 100 4.0 100 4.0 110 4.
5#4 50 3.0 50 3.0 65 4.0〃
5 70.10.5 80 9.5 8511.0//
6 50 1.0 55 0.9. 45 1.217
100 3.0 90 2.5 100 4.0 Comparative example 150 2.0 200 0.5 250 0.7
For the recording media of Examples 1 to 7, almost no deterioration of magnetic properties occurred even after the accelerated storage test, but for the comparative example, there was pinhole β staining on the 5i02 protective layer, which could prevent future oxidation and magnetic properties. Ha was significantly reduced due to promotion of oxidation by oxygen in the film layer.

Example 8 A ZnO C-axis alignment film with a thickness of 500 cm was formed by sputtering on a quartz glass with a diameter of 120 cm to be used as a transparent substrate, and then BaA7! Ga5FeA
The ZnOc
A magnetic film having a thickness of 20 and oooX was laminated on the -axis alignment film by Rf and magnetron sputtering. next,
Trunk pitch 30,000AXmF) R 1,0OO
X, a mold with a track width of 10,000'h and the magnetic thin film layer were coated with U, V, and polymers and pressed together, and the mold was removed after being cured by U, V and irradiation from the quartz glass substrate side. . This U, V, [Ag film thickness x, o as a reflective film on the uneven surface
OOX was laminated by sputtering, and a 100 μm thick methyl methacrylate polymer was further applied as a protective film using a spin cord on top of this to produce a disk-shaped magneto-optical recording medium A6.8 according to the present invention.

The Curie temperature of this magneto-optical recording medium was 205° C., Ms was 70 emVcc, and Ha was 5.5 KOe, which had good characteristics as a magneto-optical recording medium.

A magnetic field of 1QKOe perpendicular to the surface of the magneto-optical recording medium 46.8 of the present invention is applied to keep the direction of magnetization of the recording medium constant. While applying a magnetic field of .5KOe, a semiconductor laser beam with an output of 1QmW and a wavelength of 800 nm was irradiated from the direction of the transparent substrate with a pulse of about 5 mW and a frequency of IMH2 on the medium surface, and the direction of the magnetic field of the recording medium was reversed. When recording was performed on the recording medium, the bit diameter was approximately x5. o
Recorded bits of ooK were obtained.

Example 9 A magnetic thin film layer was formed in the same manner as in Example 8 except that BaGa3YFeBO1 was used as the oxide magnetic material. On top of this, a 2,000× thick 5i02 layer and a 3,000× thick a reflective film are sequentially formed as a transparent dielectric layer by sputtering to form a recording medium according to the present invention.
169 was produced. The magnetic properties of this light (-air recording medium) are as follows: Curie temperature is 210°C, Ms is 80 emu7c
c.

It had an Hc of 4.5 KOe and was excellent as a magneto-optical recording medium.

〔effect〕

The magneto-optical recording medium of the present invention constructed as described above has significant advantages over conventional recording media having an amorphous magnetic layer in that it has superior oxidation stability and magneto-optical properties.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the basic structure of the magneto-optical recording medium of the present invention, and FIGS. 2 and 3 are cross-sectional views showing other structures of the magneto-optical recording medium of the present invention. DESCRIPTION OF SYMBOLS 1...Transparent substrate, 2...Magnetic thin film layer, 3...Reflection layer, 4...Transparent dielectric layer, 5...Guide layer, 6...Shin protection layer. Patent Applicant: Ricoh Co., Ltd. - Figure 1 Figure 2 Figure 3 Figure Procedure Amendment (Foothill) August 30, 1980 1. Indication of the case 1980 Patent Application No. 74558 2. Name of the invention Oxide Ferrimagnetism and magneto-optical recording medium using the same 3,
Relationship with the case of the person making the amendment Patent applicant address 3-6 Nakamagome-chome, Ota-ku, Tokyo 143 Name (674) Ricoh Co., Ltd. 4 Date of amendment order (shipment date) July 31, 1980 5. Column 6, "Title of the invention" of the specification to be amended, Contents of the amendment (1) Description 1. Column "Oxide ferrimagnetic material and magneto-optical recording medium used therefor" for the title of the invention. "Oxide ferrimagnetic material and magneto-optical recording medium using the same".

Claims (2)

[Claims] (1) General formula “MIxM]IyFe I 2- (B
-X”?) 0195 (wherein, Me is at least one element selected from the group consisting of Ba, Sr and pb, and Mi is at least one element selected from the group consisting of Ga and a) MH is Bi, Gd. Tb, Dy, Ho, La, Y, Co, ZnXTi
, Sc. ■nX Eln, Ca, C! r, at least one element selected from the group consisting of Ni and Ge, 1≦X
An oxide ferrimagnetic material in which ≦8.0 forget≦6 and 1 forget x+y≦8, where m is the ion valence of M, and n is the ion valence of MlH. (2) In a magneto-optical recording medium consisting of a transparent substrate, a perpendicular magnetic anisotropic magnetic thin film layer, and a reflective layer, the perpendicular magnetic anisotropic magnetic thin film layer has the general formula % (%) (where Me is Ba, Sr and pb, M'i is at least one element selected from the group consisting of Ga and a, Ml is B1, GJTb, Dy, Ho, La,
Y, Co, Zn, Ti, Sc. In, Sn, C! At least 131 elements selected from the group consisting of a, Or, Ni and Ge, and 1≦X≦
8. Magneto-optical recording medium, characterized in that it is made of an oxide ferrimagnetic material represented by o4y≦6 and 14x+y≦8, where m is the number of Ml ions and n is the ion valence of MH. .