JPS60152010A - Metal oxide magnetic substance and magnetic film - Google Patents

Abstract

PURPOSE:To obtain a metal oxide magnetic substance and a magnetic film having a lowered Curie temperature Tc and enhanced coercive force Hc by a method wherein a part of the Fe atoms of MeO.n{Fe2O3}, (provided that Me= Ba or Sr, 5<=n<=6) are replaced with Cr or Ti atoms. CONSTITUTION:Sputtering is performed on a quartz substrate, whose surface is treated according to optical polishing, for 2hr in the condition that partial pressure of Ar is 2.0mm.Torr, discharging electric power is 0.35kV and the temperature of the substrate is 520-550 deg.C using a target having the composition of MeO.n{Crx.Ti3/4yFe2-(x+y)O3}, (provided that Me=Ba or Sr, 0<x<=0.5, 0<y<=0.5, 5<=n<=6) to form magnetic films of 0.2mum thickness. The Curie temperature Tc of the magnetic films becomes to 240-350 deg.C, and coercive force Hc becomes to 1,500-4,500 oersted. Accordingly, the magnetic substance having the proper Tc, Hc as the material for photomagnetically recording medium can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a novel metal oxide magnetic material and a magnetic film made of the same.

BACKGROUND OF THE INVENTION In recent years, magneto-optical recording media in which magnetic recording is performed using semiconductor laser light have been researched and developed for high-density recording. Conventionally, magnetic materials used in magneto-optical recording media are often made of amorphous alloys of rare earth metals and transition metals. To make a magneto-optical recording medium using such an amorphous alloy magnetic material, the magnetic material, for example, a Tb-Fe alloy, is generally deposited on a substrate such as a glass plate to a thickness of 0 by vacuum deposition, sputtering, etc. A magnetic film is formed by depositing the magnetic material to a thickness of about .1 to 1 μm. Recording on the magneto-optical recording medium obtained in this way,
Reproduction is performed as follows. That is, recording takes advantage of the characteristics of rapid changes in coercive force corresponding to temperature changes near the Curie temperature or compensation temperature of the magnetic film, and magnetizes the magnetic film by irradiating and heating it with a laser beam modulated with a binary signal. This is done by reversing the direction of the Further, reproduction is performed by reading out the data by utilizing the difference in the magneto-optical effect of the magnetic film after the inverted recording. Magneto-optical recording media using amorphous alloy magnetic materials as mentioned above have high recording sensitivity, so they can be recorded at high speeds (frequency 1M) using semiconductor laser light.
Is there an advantage in being able to record at a high frequency (Hz)? However, since amorphous alloy magnetic materials, especially transition gold (Li) components, are susceptible to acid oxidation, the major drawback is that the magneto-optical properties of the magnetic film deteriorate over time. be.

To prevent this, a layer of Sin is applied on the amorphous magnetic film.

It is also known to provide an N-holding film such as Sin (the formation method is by vacuum evaporation, sputtering, etc., as in the case of the magnetic film), but it remains in the vacuum when the magnetic film or protective film is formed. 2. The magnetic film is oxidized and corroded over time due to O, H, O, etc. adsorbed on the substrate surface and O, H, O, etc. contained in the target of the alloy magnetic material. Heat further accelerates this oxidative corrosion. In addition, amorphous magnetic materials have the disadvantage that they are easily crystallized by heat, which tends to cause deterioration of their magnetic properties. Furthermore, as a reproduction method to improve the reproduction output, the magnetic film is made as thick as possible, a reflective film such as Cu, AQ + Pt + Au is provided on top of it, and after the laser light is irradiated through the magnetic film and transmitted, it is reflected by the reflective film. The reflective Farate method that detects this reflected light is advantageous in that it can obtain a signal with a high S/N ratio, but since conventional amorphous magnetic films lack light transmittance,
It could not be used in this method.

l-An object of the present invention is to provide a novel metal oxide magnetic material which has high recording sensitivity, excellent oxidation corrosion resistance and light transmission properties, and is particularly suitable as a material for magneto-optical recording media, and this metal oxide magnetic material. An object of the present invention is to provide a magnetic film consisting of the following.

Structure The metal oxide magnetic material of the present invention is represented by the general formula (1) (% formula %), and the magnetic film is made of the metal oxide magnetic material of the general formula.

The magnetic material or magnetic film used in magneto-optical recording media has magneto-optical properties (
In particular, the Curie temperature 1'c must be low to obtain high recording sensitivity, and the coercive force Hc must be low to maintain the recorded memory stably. It needs to be moderately high. Generally, the appropriate range for Tc and Hc is 10 for Tc.
0~;550℃, 300~600 for To1c
It is considered to be 0 oersted. This means that Tc is 100'c
Below, the recorded memory becomes unstable due to the laser beam at 14 degrees, causing deterioration of playback characteristics, and recording with semiconductor laser beam is difficult at temperatures above 350°C, while on the other hand, when 1-1c is below 300 oersted This is because there is a possibility that the memory becomes unstable and disappears, and if it exceeds 6000 Oerst 1 -, the laser output and external magnetic field required for magnetization reversal during recording become large, which is not desirable.

On the other hand, metal oxide magnetic materials have been studied as magnetic bubble materials. Among these hexagonal crystal systems, those represented by the general formula (2) (where Mean is the same as in the general formula (1)) are known. The present inventors discovered that this type of magnetic material is itself an oxide.

It was noted that there is no fear of oxidative deterioration and that it has light transmittance even at a film thickness of 107J. However, since the Curie temperature Tc of these materials is as high as 450'C or more, recording with semiconductor laser light is difficult as described above, and they cannot be used as materials for magneto-optical recording media. Therefore, the present invention: Tora conducted various studies and found that when a part of the F c atom in general formula (2) is replaced with Cr or T1 atom,
We found that 1゛c decreased in both cases of C substitution and Ti substitution.At the same time, we found that Hc increased in the case of Cr substitution, but decreased in the case of T1 substitution. T i li!!Transformation B a F
e +2-z MZ O19 (M is Cr or 'I'
,i.

2 represents the number of Cr or Ti substitutions. ) showed a tendency as shown in Fig. 1 for 1゛c, and a tendency as shown in Fig. 2 for llc. Therefore, the present inventors focused on the switching effect of Cr and 1゛, and further improved the Tc and H required for magnetic materials or magnetic films for magneto-optical recording media.
As a result of substituting a part of Fc in general formula (2) with two metals, Cr and Ti, in various proportions in consideration of the appropriate range of c, the metal oxide magnetic material of general formula (1) was obtained. The present invention was achieved based on the discovery that it provides excellent properties as a magneto-optical recording medium.

In this way, the present invention solves the problem of the general formula (2
) By substituting some of the Fe atoms in the total bending compound with Cr and Ti atoms, the Curie temperature can be lowered while maintaining the moderately high coercive force required for memory, making it possible to record using semiconductor laser light. , reproduction is possible, and thus it can be applied as a material for magneto-optical recording media.

As can be seen from the above description, the metal oxide magnetic material of the present invention satisfies the appropriate Curie temperature range and appropriate coercive force range required as a material for magneto-optical recording media.

For example, [3aCrx'Tiy' F[317+ X'
+v' + 0tq (where X' is the number of Cr substitutions and y' is the number of Ti substitutions), Tc is as shown in Figure 3, when the number of substitutions ' is 2.0
0, it is 260°C; .6 Elsteso 1-
It is. Due to these Tc and Hc characteristics, the metal oxide magnetic material or magnetic film of the present invention can be applied as a material for magneto-optical B media that performs recording and reproduction using semiconductor laser light. It has features such as high sensitivity, oxidation corrosion resistance, and translucency.

To make the metal oxide magnetic material of the present invention, a predetermined amount of Ba is required.
CO3 or S r CO, and Fe, O.

1200~14
It is sufficient to sinter at a temperature of 00°C.

The metal oxide magnet of the present invention obtained as described above (/1
The P-body side of the body is 1, S XIL] ' 5.2 (Cra, r T j
,tc r e/,? 03).

13 ao・5.2 (Cr,, Ti,, CFe,,
,O,) 1r(al”'J・5.4 (Cr1.T
i,,J,Fe,,03) IB ao ・5.4
(Cr,,T t,,,F e,,o,]) IB a
o・5.6 (Cr,,A Ti,,,Fe,o,1
) IB ao・5.6 (Cr,, T i,,,,
Fe, jo,”) IB a 0 ・5.8 (Cr,
, T i, , F e, 7 03).

B a 0 ・5-8 (Cr62 T:, x F
et,eO,).

Sr0・5.4 (Cr,j Ti,,Fe,,oa
)ISro・5.6(Cr,,Ti,,,Fe,,oi
).

etc.

In order to further increase the Faraday rotation angle and improve the magneto-optical properties of the metal oxide magnetic material described above, Go
+ B i + V + L a + Y, Y b
+S m, '1' b, D y, G d
Metals such as can be added.

To make a magnetic film using the metal oxide magnetic material of the present invention,
Although it depends on the type of substrate, generally this magnetic material is vacuum-deposited onto the substrate at a substrate temperature of 500 to 600°C.
The film may be deposited to a thickness of about 0.1 to 10 μm using methods such as sputtering and ion blasting. In this way, as shown in FIG. 5, a perpendicularly magnetized magnetic film 2 is placed on the substrate 1.
A magneto-optical recording medium having the following properties is obtained. In some cases, the magnetic film may be formed at a substrate temperature of less than 500°C. However, in this case, after forming the magnetic film, 500~
Heat treatment at 700°C while applying a magnetic field by w-coupling.
It is necessary to perform perpendicular magnetization. Here, the substrate materials are generally heat-resistant metals such as aluminum; quartz glass: GGG; sapphire; lithium tantalate; crystallized transparent glass; Pyrex glass; single-crystal silicon with or without surface oxidation treatment; AQ20.
, AQ, O, ·MgO.

Mg0-LlF, Y, O, ·LiF, Bed.

Zr0t 'Y20. + Transparent ceramic materials such as The2''CaO; inorganic materials such as inorganic silicon materials (e.g., Tosguard manufactured by Toshiba Silicon Co., Ltd., Sumiceram P manufactured by Sumitomo Chemical Co., Ltd.), or organic materials such as acrylic resin, polycarpoy, -71 ~ resin, polyester resin, etc. Can be used.

The magnetic film of the present invention is applicable not only to a single-layer magneto-optical recording medium as shown in FIG. 5, but also to all conventionally known multilayer magneto-optical recording media. Examples of this type of multilayer type include structures shown in FIGS. 6 to 9. In the figure, 1' is a guide track (=J substrate), 3 is a reflective film, 4 is a transparent dielectric layer, 5 is a guide track layer, 6 is a protective film, 7 is a transparent adhesive layer, and 8 is a heat-resistant layer. The guide track and board are made of organic materials such as those described above by molding, extrusion molding,
It is made by adding an etching method to a fluorocarbon film. Note that the guide track on the substrate guides the laser beam during recording and reproduction. Anti-IJ film 3 is C11, ΔQ, Ag
, Au, Pt.

T e Ox + T e CT S eΔs, TeA
s, TiN, TaN, CrN + cyanine dye, phthalocyanine dye, etc., are deposited on the target surface to a thickness of 5.
It is formed by attaching it to about 00 to 10,000 people. Note that this reflective film is provided for the purpose of increasing the Faraday effect by reflecting the laser light that has passed through the magnetic film and transmitting it through the magnetic film again. The transparent dielectric layer 4 is S
i○2+siO.

TiO2, Ti○, CeO, HfO2, Bed.

It is formed by depositing The, ', Si, N, etc. on the target surface in the same manner as described above to a thickness of about 0.05 to 0.5 μm. Note that this transparent dielectric layer is provided for the purpose of increasing the Faraday rotation angle and improving the reproduction output. The guide track WJ5 is formed by applying an ultraviolet curable resin to the target surface, pressing a mold having a guide groove thereon, and then curing the resin by irradiating ultraviolet rays. Ho W! n'; i6 is acrylic resin, polyurethane resin, polycarbonate 1-resin, polyether sulfone resin, polyamide 1-resin, epoxy resin, TiN
, Si, N4. TaN, 5in2. In the case of resin, Si○ etc. is applied by coating method, and in other cases, it is applied to the target surface by methods such as vacuum evaporation, sputtering, ion blasting, etc. to a thickness of approximately 0.
．． It is formed by applying +R to about 1 to 1071 m. Note that this protective film is provided for the purpose of protecting the reflective film 3.

Jl Ming Waka 1i'+ 7 is a kite 1 equipped with a reflective film 3.
~Rack (i with reflective film and magnetic film 2 on J-shaped substrate 1')
-I fever J? '78 (Since this layer is made of the above-mentioned inorganic material, the "heat-resistant layer provided with a magnetic layer" refers to the above-mentioned single-layer type magneto-optical recording material f'l.) with an epoxy resin, Approximately 2 to 100μ of resin such as polyurethane or polyamide
It is formed by adhering to a thickness of approximately m. That is, this transparent adhesive layer is simply a layer for bonding the reflective film 3 on the substrate 1' and the magnetic film 2 of the single-layer magneto-optical recording material. Note that the heat-resistant WJ8 is made of an inorganic material as described in Section 11, and thus corresponds to the substrate 1, but is provided here for the purpose of improving the heat resistance of the magnetic film 2. Appropriate thickness is about 10 to 500 μm.

Recording and reproduction on the above-described magneto-optical recording medium using the magnetic film of the present invention is carried out by irradiating modulated or deflected laser light from the magnetic film or substrate side, as in the prior art.

Effect: Although the metal oxide magnetic material or magnetic film of the present invention has appropriate 1°C and Hc as a material for magneto-optical recording media and has high recording sensitivity, it has oxidation and corrosion resistance that conventional products did not have. Since the material is transparent and magneto-optical, its magneto-optical properties do not deteriorate over time, and transmitted light can also be used during reproduction, making it possible to reproduce using a Faraday rotation angle that provides a high reproduction output.

Examples of the present invention are shown below.

Examples 1 to 10 Each of Targetera 1- having the composition shown in the table below was used to apply a Δr partial pressure of 2. OmmT
o r r, 02 partial pressure 0.3 mm' [o r r
, a 0.2 μ thick magnetic tj was sputtered for 2 hours under the conditions of discharge force o, 35 KV, and substrate temperature of 520 to 550°C.
llf was formed. The Curie temperature of these magnetic films]'c
The results of measuring the coercive force Hc are shown in the table below.

Next, each magneto-optical recording medium obtained in the following manner was magnetized in one direction, and a semiconductor laser with an output of 20 m 11 was applied while applying a magnetic field of 0.5 oersted opposite to the direction of magnetization. When recording was performed by irradiating light with a pulse of intensity 10 mW and frequency IMIIz on the surface of the recording medium to cause magnetic reversal, recording bits with a pitch of 1 to about 1.5 μm were formed in each case.

[Brief explanation of drawings]

1 and 2 show metal oxide magnetic material 138F, respectively.
e lp -Z Mz○3. (M is Cr or F1.2
is the number of substitutions of Cr or Ti), the number of substitutions of Cr or 'I゛1 is 2, the Curie temperature TL] and the coercive force of 1-10. Oxide magnetic material BaCrx'TiV' Fe1. −t x'+y'
The number of substitutions Y' of 'J゛1 in IO+q (χ' is the number of substitutions of Cr, Y' is the number of substitutions of 1゛], and]c and l-
1c and FIGS. 5 to 9 are groove diagrams of an example of a magneto-optical recording medium using the magnetic material or magnetic film of the present invention, respectively. 1 ・Substrate 1' ・・Guide (・Rack 4 base 4 anti-2 ・Magnetic film
3 Reflective film 11・Transparent dielectric layer 5 Guy[・Track H6 protective film
7 Transparent contact:)', + Jj'18 ・Heat resistance Layered rough 1 figure Punishment 3 figure u I 2 Tsuta 2 figure Hanging 4 figure U I 2 Shizu 5 figure Punishment 7 figure Punishment 9 figure Punishment 6 blade also 81 Procedural amendment 1981 Patent Application No. 7596 2 Name of the invention Metal oxide magnetic material and magnetic film 3 Relationship to the person making the amendment case Patent applicant 1-3-6 Nakamagome, Ota-ku, Tokyo (674) Stock Ricoh Company - Representative Hama 1) Hiro 4, Agent 5, Column 6 of "Detailed Description of the Invention" of the specification to be amended, content of the amendment, "Transition" in the first line from the bottom of the second page to "Rare Earth ”. Correct "μ" in line 2 of page 6 to "μm". 1. Change "500~600℃" in line 1 of page 10 to "500~600℃"
Correct to 700℃. +41 Change “500 to 700℃” in line 8 of the same page to “500 to
Correct to 800℃. (51 Page 10, line 1 from the bottom to page 11, line 2, “Inorganic materials......(omitted)...Can be used.”) 1 Inorganic materials are used (6) Correct “Teral.” on page 13, line 16 to “1.” (7) Correct “Kv” on page 10, line 1 to “key”. 550"
is corrected to 17oJ. '°゛ Correct "Fμ" in line 16 of the same page to [μm]. Correct [o, s J on page 15, line 3 to [s o oJ. that's all

Claims (1)

[Claims] [, general formula %formula%] ) A metal oxide magnetic material represented by . 2. General formula %formula%] ) A magnetic film made of a metal oxide magnetic material.