JPS61265756A - Photomagnetic recording medium - Google Patents

Abstract

PURPOSE:To improve corrosion resistance without spoiling magnetic characteristics by incorporating >=1 kinds of either Ru or Al into a magnetic film consisting of a specific amorphous are earth-transition metal alloy. CONSTITUTION:The amorphous alloy film of a photomagnetic recording medium having a substrate and the amorphous alloy film which is deposited on the substrate and has the axis of easy magnetization in the direction perpendicular to the film plane is the magnetic rare earth-transition metal alloy film which contains Ru and/or Al as the additive element and is expressed by the formula. Said film is constituted of 10-40at% rare earth metal, 60-70at% Fe, <=20at% Co nd the balance Ru and/or Al. R is selected from Tb, Gd and Dy and A is selected from Ru and/or Al, (x), (y), (z) are the values within a 0.10<=x<=0.40, 0<=y<=0.20 and 0.01<=z<=0.20 range. The spoiling of the magnetical and photomagnetical characteristics is thereby obviated and the improvement of the corrosion resistance is made possible.

Description

[Detailed description of the invention] “1 man! The present invention relates to an erasable and rewritable optical disk, and more particularly to a magneto-optical recording medium carrying a magnetic recording film with excellent corrosion resistance.

BACKGROUND ART Traditionally, Mn has been used as a magnetic recording film for magneto-optical recording media.
Polycrystalline thin films such as Bi, vn cu s; and Gd I
Single crystal magnetic Carnet thin films such as G, Bi Ss Er Ga IG, Gd Co , Gd Fe, Tb
Fe.

DyFe, GdTbFe, TboyFe
, Tb FCCO and other rare earth-transition metals are known.

In these magnetic recording films, there are various issues such as film formation ability to produce IIIQ with uniform characteristics over a large area on a substrate such as plastic or glass at a relatively low temperature, writing efficiency to write signals with small photothermal energy, and There is a need to improve the readout efficiency and the like in order to read out the input signals with a good S/N ratio. Now, vn s; , vn
Polycrystalline films such as CUSU have deterioration in magneto-optical properties due to crystal transformation, and are considered difficult to put into practical use due to large media noise due to fluctuations in magnetic properties on or within the media surface due to crystal grain boundaries. There is.

Gd1G and single crystal magnetic garnet substituted with various elements are transparent to visible light, allowing for a long optical path length and therefore a large optical reproduction output, but their optical absorption coefficient is small and recording is difficult compared to polycrystalline garnets. This requires a considerable amount of laser power, making it difficult to increase the area.

Therefore, recently, among the above-mentioned thin films, amorphous alloy thin films are considered to be excellent as magneto-optical recording films with less media noise. Especially GdTbFe.

Amorphous alloy films such as Tb Fe Co and Gd Tb Fe Co have a relatively large Kerr rotation angle, so they can have a large S/N ratio, and the Curie temperature is around 150°C, which is a suitable temperature, making them suitable for magneto-optical applications. It is said to be suitable as a recording film, and research toward its practical use is being actively conducted.

A disadvantage of putting these amorphous rare earth-transition metal alloy thin films into practical use as magneto-optical recording films is that they have poor corrosion resistance. That is, the alloy film not only corrodes in a high-temperature and humid atmosphere and deteriorates its magnetic and magneto-optical properties, but also has the disadvantage that it eventually becomes completely oxidized and becomes transparent.

Therefore, in order to improve the corrosion resistance of such an amorphous rare earth-transition metal alloy film, Cr s Ni s Ti is added to the alloy.
There are methods of adding additive elements such as
There are methods of providing a protective film such as iO1SiO2, and methods of sealing inert gas in a sealed space in which an amorphous alloy film is placed to suppress deterioration of characteristics as a magnetic recording film due to oxidation, and methods of bonding substrates together. Magneto-optical recording media and the like having a disk structure in which an amorphous alloy film is sandwiched have been proposed.

However, these techniques still have problems. That is, conventional additive elements have a disadvantage in that they have little effect on improving corrosion resistance unless added in large amounts, and adding large amounts leads to deterioration of magnetic properties and magneto-optical properties. Further, if the protective film on the amorphous alloy film is formed thinly, it is difficult to prevent pitting corrosion, and if it is thickly formed, cracks may occur due to stress strain of the protective film during film formation. Furthermore, the methods of filling inert gas and bonding substrates have drawbacks, such as the fact that it is difficult to do so without imposing thermal and physical burden on the magneto-optical recording medium, and it is also difficult to maintain confidentiality. Therefore, a magneto-optical recording medium with sufficient corrosion resistance has not yet been obtained.

Summary of the Invention An object of the present invention is to provide a magneto-optical recording medium in which the corrosion resistance of the magneto-optical recording film itself made of an amorphous alloy 'R film is improved without impairing the magnetic and magneto-optical properties. .

The magneto-optical recording medium of the present invention is a magneto-optical recording medium having a substrate and an amorphous alloy film supported on the substrate and having an axis of easy magnetization in a direction perpendicular to the film surface. The film is a rare earth-transition metal alloy thin film containing RLI and/or All as an additive element, and rare earth metal 10-4Q.
at. % and Fe60-70at. % and GO20at
．． % or less, and the remainder of RU and/or AQ.

Friend-Emperor-1 Embodiments of the present invention will be described below with reference to the accompanying drawings.

匪J Place the next substrate and target at predetermined positions in the chamber of the high frequency sputtering device. substrate:
7.62cm (3 inches) square white plate glass 1st target: Diameter approx. 10.2cm (4 inches) thickness 5#l
00 pieces and Tb pieces, each 51R square and 1 mra in thickness, are uniformly arranged on a lI Fe disk so as to obtain the desired alloy composition.Second target: Approximately 10.2 cm (4 inches) in diameter Al with a thickness of 6 tnm! After evacuating the inside of the disk chamber to 2×10 Torr, high-purity Ar gas is introduced to 3×10 Torr, and the Ar gas pressure is set to 2×10 −2 Torr by operating the main valve of the evacuation system.

A high frequency power source applies a sputtering power of 250 W to the first target while keeping it constant, and applies a different sputtering power to the second target while changing the sputtering power from 10 to 200 W.

By the dual simultaneous high-frequency sputtering method under these conditions, Tb FeC with the following composition (ω, (to and (C))
o l; LTb Fe Co A IJ amorphous alloy 11
51 (constant number of 1,500 people).

” ■bO,20([80,86C00,14)
0.80Cb+(Tb(FeCo)
) /VO,200,86G,14 0.8
0 0,95 0.05+c+ (Tb o, 2o (
Fc, 86600.14) 0.80) 0.90
0.10 Note that the alloy to which 15 at.% or more of All was added was a magnetic film that did not have an axis of easy magnetization in the direction perpendicular to the film surface.

Next, as a weather resistance test, TbFCCO and TbFCCO with the above configuration were tested.
b A magneto-optical recording medium consisting of a substrate supporting Fe Co AQ amorphous alloy 11111 is placed in a constant temperature and humidity chamber at 45° C. and 90% RH to examine changes over time.

The Kerr rotation angle θk is set by @e-Ne laser (
The alloy was measured using an optical microscope (wavelength: 633 nm).
The surface of the thin film is observed, and at the same time, the recording power of the amorphous alloy thin film is also measured.

FIG. 1 shows a magneto-optical recording medium (hereinafter (a), mountain) and (C) using an amorphous alloy H film of a rare earth-transition metal alloy added with All of the above (al, city) and (C), respectively. 2 is a graph showing the results of a weather resistance test of 2000 (hereinafter referred to as "A"), and shows changes in characteristics with respect to the Kerr rotation angle θ with respect to the amount of Al added. In this graph, the vertical axis shows the rate of variation in the Kerr rotation angle θ, the horizontal axis shows the elapsed time, and (ω, (b) and (C) show the characteristic lines of the magneto-optical recording medium of the respective signs.

No AQ addition (the rice becomes transparent after 3 days due to oxidation,
It becomes impossible to measure the Kerr rotation angle θ. On the other hand, A
No significant pitting corrosion was observed even after 30 days in the case of Ichi) and (C) with 11 addition.

Figure 2 shows the Al of (ω, mountain) and (j (C) at room temperature.
This is a graph showing the dependence of added AQIIrl on the Kerr rotation angle θ of the l-added alloy film, where the vertical axis shows the Kerr rotation angle θk and the horizontal axis shows the A (l addition amount. As shown in the figure, the Kerr rotation angle θ
By adding 89 to 5 at. %All addition (mountain)
) up to 10 at. %A
It drops sharply with Q addition (<C>).

FIG. 3 is a graph showing the dependence of the recording power of (al, +tn, and (C)) on the degree of addition of aluminum at room temperature, where the vertical axis shows the recording power and the horizontal axis shows the AQ doping groups. , the recording power increases as the amount of All added increases (ω,
It decreases in the order of +to and (C).

W2 Example R was carried out using the same process as the first example above except for the following conditions.
The LI-added amorphous alloy film shown below (small, (e), +f+
And (9) TbFeC0Ru alloy was prepared in general.

Near the substrate, 621 (3 inch) square white plate glass first target: diameter approximately 10.2 cm (4 inches) thickness 5Ill
00 pieces and Tb pieces, each 5NR square and 1 inch thick, are uniformly arranged on a Fe disk of I so as to obtain the desired alloy composition.Second target: diameter of approximately 10.2 CI (4 inches) Ru disk (d' (Tb0.20 (Foo, 86C00,14
) 0.80) 0.95RUO, 0530ゝ”b
O, 20"80.86"0.14) 0.80)
0.90” 0.10(r) (Tb o, 2o (F
e0186"0.14) 0.80) 0.85" 0
．． 15 Also, the conditions for the weather test, the method for measuring the Kerr rotation angle θ, etc. are carried out in the same manner as in the first embodiment.

In addition, in the above Tb Fe Co Ru alloy film, RLJ
is 25 at. % or more was a magnetic film that did not have an axis of easy magnetization in the direction perpendicular to the film surface.

Figure 4 shows the magneto-optical recording media (hereinafter referred to as (small, small,
3 is a graph showing the results of the weathering test of (e), (f) and <Ql), and shows the change in characteristics of the Ru-added alloy film with respect to the Kerr rotation angle θ with respect to the Ru-added peak. In the graph, the vertical axis shows the rate of variation in the Kerr rotation angle θ, and the horizontal axis shows the elapsed time, and (small, (e), +f+, and (g+) each show the characteristic line of the magneto-optical recording medium of the sign. The Ru-added alloy film is slightly inferior in overall corrosion resistance compared to the All-added alloy film, but the one with 20 at.% RLJ addition (Q) has a corrosion resistance of 3.
No significant pitting corrosion was observed even after 0 days.

Figure 5 shows (small, (e), (f) and (0)) at room temperature.
2 is a graph showing the dependence of the added Ru concentration on the Kerr rotation angle θ of the Ru-added alloy film, where the vertical axis shows the Kerr rotation angle θk, and the horizontal axis shows the amount of RLI added. Kerr rotation angle θ as shown
As the amount of Ru added increases, it gradually increases in the order of (small, (e), and decreases in the order of (1). In this tendency, the Kerr rotation angle θ is 10 at.

%RLI addition ((e+)) reached the maximum.

Figure 6 shows the addition R of the recording power of the Ru-added alloy film at room temperature.
This is a graph showing uII degree dependence, where the vertical axis shows the recording power and the horizontal axis shows the amount of Ru added. As shown in the figure, as the amount of Ru added increases, the recording power gradually decreases (mountain, (e)
, <f), and (9) tend to increase in this order.

Third Example The same process as the first example above was used except for the following conditions.
The uAQ-added amorphous alloy films below (h), (i), +
j+, (k>, (1), (plane, Tb of (n) and (0)
A FeCoRuAl1 alloy film is created.

Near the board, 62C11 (3 inch) square white glass plate 1
Target: Diameter approx. 10.2C11 (4 inches) Thickness 5
A CQ piece and a Tb piece each having a diameter of 5 square meters and a thickness of 1 inch were uniformly arranged on a l''e disk of 1 inch so as to obtain the desired alloy composition.Second target: Diameter of approximately 10.2 CI (4 mm). inch) 511II square on AQ disk of 6aw thickness, R of 1g++ thickness
U pieces arranged uniformly (■bo, 20 (Feo, tbCOo, tf”I
O, 16) o, ri o ("p, zp" a, t
o> a, t.

Mountain (■bo, zo (Fea, 16COo, t) t>a,
gO) a, 9° ("tts'1.to) o, 1° (J)
(T bff,,,(F'36.PIC01,tp
) o,tto) ty,? ρ(“o, so” a
5o ” ”(kl (Tb, pzg< F ea16
COg, tp) o, 26) o-ra0 ("t!'
, 60A' a, H>σ, t.

(I) (■bi2.217(Feg, piCoO, I
g) t), BO) 6. yO(Ruo, ION o, 2
0)l)Iρ(m) (T bo,xo(F e,,s
a CO,,7g)6. y, ) /, pg (Ru 6
．． y/di yao') ip, er(n'("o
, 2g (Fea, BCOp, 15t) 63c) Kite gg
(Ruy6pMypρ>/, 15'(0) (Tb0j
(7(Fe,,16Coa,tlt>/,20)/,
.

FIG. 7 shows a magneto-optical recording medium (hereinafter, respectively (
This is a graph showing the results of weathering tests of RuAl! The characteristic changes in the Kerr rotation angle θ with respect to the total RuA addition value of the additive alloy film are shown. In the graph, the vertical axis shows the fluctuation rate of Kerr rotation angle θ, the horizontal axis shows the elapsed time, and (kl, +
m), (n3 and (0) respectively indicate the characteristic lines of the magneto-optical recording medium with the respective signs. The larger the amount of RuAQ added, the more the Kerr rotation angle θ deteriorates (m+, +k), (n), ( 0) decreases in the order of 15 at.% and 20 at.%.
3 for alloy films ((n) and (0)) with %RuAl1 addition.
No significant pitting corrosion was observed even after 0 days.

FIG. 8 is a graph showing the dependence of added RUAU11 degrees on the Kerr rotation angle θ of a RuAl1-added alloy film at room temperature, where the vertical axis represents the Kerr rotation angle θk, and the horizontal axis represents RLIAR addition and added water. As shown in the figure, RtlAl is applied to the Kerr rotation angle θ.
((2), (k), (n
), and then decreases ((0) >.In this tendency, the Kerr rotation angle θ has a value of 15at.%RuAl1
The maximum value was reached with addition (+n>).

Figure 9 shows RuAl at 1m! This is a graph showing the dependence of the recording power of the additive alloy film on the RuAl11 degree addition, where the vertical axis shows the recording power and the horizontal axis shows the RuAl1 addition level. As shown in the figure, the recording power tends to increase little by little in the order of (k), (n), and (0) as the RuAl1 addition amount increases.
7) (n) (7) Recording pa'7-4.14111W, 2°at. % (0), it rises to nearly 5 mW.

Figure 10 shows the above +h), (j), (k) and (1).
This is a graph showing the results of a weathering test of magneto-optical recording media (hereinafter referred to as "mountain", "mountain", "<j+", "+" and (1), respectively) made of amorphous alloy thin films of Tb Fe Co and Ru.
The atomic ratio of AQ is Tb Fe Co :Ru AQ=9
:RuA when fixed at 1 and changing the atomic ratio of RU and Al
The characteristics change with the Kerr rotation angle θ of the Q-added alloy film is shown. In the graph, the vertical axis shows the rate of variation in the Kerr rotation angle θ, and the horizontal axis shows the elapsed time, and (h), the peak, +j+, + and (1) show the characteristics of the optical recording medium of that sign. Each line is shown.

A (the larger the amount of l added, the more h), +i+, +j+, t
The deterioration in the Kerr rotation angle θ also tends to decrease in the order of k) and (1).

FIG. 11 is a graph showing the dependence of the added Ru/AQ ratio on the Kerr rotation angle θ of a RuAl1-added alloy film at room temperature, where the vertical axis shows the Kerr rotation angle θk and the horizontal axis shows the Ru//l ratio. . The Kerr rotation angle is determined by the Ru addition m as shown in Figure 11.
The more (+), +, out, (j), (h) improves in this order.

Figure 12 shows RtlAl! at room temperature! This is a graph showing the dependence of the recording power of the additive alloy film on the added Ru/AU ratio, where the vertical axis shows the recording power and the horizontal axis shows the amount of RuAQ added. As shown in FIG. 12, the recording power increases as the amount of AQ added increases, but it did not exceed 4 mW even when the ratio of RU to AQ was Ru:Δ1l=2:8.

Here, for comparison in Figures 4 to 12 (all
The characteristics of (C) and (e) are also shown.

Note that the amorphous rare earth-transition metal alloy film of the above example is expressed by x, y, and z as atomic ratios. In this example, R was Tb (may be 3d and Dy, or a combination thereof. A is RLI and/or AQ. x1y%2 is 0.10≦X≦0.40.0 ≦y≦
A similar effect can be obtained if the value is in the range of 0.20 and 0.01≦2≦0.20.

In the above embodiment, only an amorphous alloy film was formed as a magneto-optical recording medium on a white glass substrate by a sputtering method, but the substrate may be made of metal such as Ail,
AQ-Mg alloy, plastic (e.g. PMMA, PC
etc.), and the film forming method may be ion beam sputtering or vacuum evaporation. In addition, when forming the magneto-optical recording medium according to the present invention on a substrate made of glass, metal, plastic, etc. by sputtering, vacuum evaporation, etc., a well-known protective layer or an antireflection layer that also serves as a protective layer or a heat insulating layer may be applied on the recording medium. Providing a layer further improves corrosion resistance.

Furthermore, it goes without saying that the corrosion resistance can be improved by using the conventionally known air sandwich structure in which an inert gas is trapped or by bonding the substrates together.

Furthermore, in order to improve the Kerr rotation angle, a film having a higher refractive index than the substrate is provided between the substrate and the recording medium to provide an enhancement effect, thereby further improving the S/N ratio.

As described above, in the magneto-optical recording medium according to the present invention, an amorphous rare earth-transition metal alloy magnetic film, for example, Tb Fe
A suitable amount of one or more of Ru and AU is added to the Co alloy.
By incorporating it at once, it is possible to obtain a magnetic film with improved corrosion resistance and improved magneto-optical effect without impairing magnetic properties.

[Brief explanation of the drawing]

Figure 1 shows the change over time in the Kerr rotation angle θ of Tb Fe Co and Tb Fe Co A (1 alloy films) left in a constant temperature and humidity chamber at 45°C and 90% RH.
Figure 3 shows the change in Kerr rotation angle when Δ9 is added to FCCO, Figure 3 shows the change in recording power when Ail is added to Tb Fe Co, Figures 4, 5 and 6 are Figures 7, 8 and 9 show the same things as in Figures 1, 2 and 3 for the case of RLI addition; Figures 10, 11, and 12 showing the addition of AQ are similar to Figures 1, 2, and 3 when the proportion of RuAQ is changed. Applicant: Pioneer Corporation B% * a * t * 藺 1 So, 3 concave Al◆ (Qff, %) Gin U Yuroba [hours]

Claims (2)

[Claims] (1) A magneto-optical recording medium comprising a substrate and an amorphous alloy film supported on the substrate and having an axis of easy magnetization in a direction perpendicular to the film surface, the amorphous alloy film containing Ru as an additive element.
and/or a rare earth-transition metal alloy thin film containing Al, and containing 10 to 40 at. % and Fe60~7
0 at. % and Co20at. % or less, and the remainder of Ru and/or Al. (2) The amorphous rare earth-transition metal alloy film has the following formula using x, y, and z as atomic ratios: {R_x(Fe_1_-_yCo_y)_1_-_x}
It is a thin film of a multi-component alloy having a composition represented by _1_-_zA_z, where R is one or more rare earth metals selected from Gd, Tb and Dy, and A is one or more added rare earth metals selected from Ru and Al. metal, x is 0.10
A value in the range of ≦x≦0.40, and y is 0≦y≦0
．． 20, and z is 0.01≦z≦
2. The magneto-optical recording medium according to claim 1, wherein the value is in the range of 0.20.