JPS6140011A - Material for photomagnetic recording - Google Patents

Abstract

PURPOSE:To obtain the material for photomagnetic recording having excellent corrosion resisting property by a method wherein an alloy of the prescribed composition, consisting of one or two kinds R of Gd, Tb and Dy, M of Al and Co and Fe, is used. CONSTITUTION:In an Fe-R-M alloy, R has 20-35atm% of the total quantity, and Al and Co have 3-20atm% of the total quantity of Fe+M. When the alloy 2 of the above-mentioned composition is used, the corrosion resistance of the titled material is remarkably improved mainly due to the action of Al, the stability of recording is improved, and the repeatability of writing-in and eration can also be increased remarkably. Also, the material alloy of this constitution has the property which is suited for a high density recording, Kerr rotational angle is increased by containing Co, and the reproduction SN ratio is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to optical recording materials, particularly magneto-optical recording materials.

(Traditional Art) In the field of information processing technology, with the rapid increase and diversification of information, there has been a recent demand for an increase in the recording capacity of magnetic memory, the number of writes, etc. It is increasing. Therefore, as an alternative to the conventional recording method,
The optical recording method using a recording medium is, for example, 1. Magazine (Electronic Outlook, November issue (11183) Seibundo Shinkosha, p. 63
~74).

The conventional example disclosed herein will be explained.

First, there are those using metal thin films or metal-containing polymer materials. In this method, the recording part of the recording medium is melted and vaporized using a laser beam, and a hole is punched and written.
Yes, rewriting is not possible.

On the other hand, examples of rewritable optical recording media include those that utilize the photodarkening phenomenon of amorphous chalcogenide materials, but such amorphous chalcogenide materials generally have low recording sensitivity and a light absorption edge. It is on the short wavelength side, and since the absorption is small at wavelengths near the absorption edge 7, the recording sensitivity with long wavelength light is very low.By the way, laser light generally has good directionality and can be focused on an extremely small spot. It is suitable for use as a light source for optical recording media. Further, since semiconductor lasers can be extremely miniaturized, they are attracting particular attention as light sources. However, at present, the oscillation wavelength range of semiconductor lasers is 750 to 800 nm.
m or more, and perhaps in the future? It has a relatively long wavelength of approximately flOn+w. Also, even with He-Me lasers, which are generally small and have good stability, their wavelength range is 832.8.
Although the lasers are short-wavelength lasers such as Ar and R, they are somewhat unstable, have increased power, and the device itself is large. For this reason, with the amorphous chalcogenide mentioned above, when a semiconductor laser or Ha-Me laser is used as a light source, the recording sensitivity becomes low, whereas when a laser such as Ar or Kr is used, the memory device becomes significantly large. It becomes.

Another optical recording medium is a medium that combines a thermoplastic and a photoconductor, and this recording medium has the advantage that the wavelength range used can be changed by freely selecting the photoconductor.

The number of times that it can be rewritten is at most 100 times,
In addition, there is a drawback that individual recorded bits cannot be selectively erased, and the entire area within a certain area is erased, and processing corresponding to the recent increase in the amount and diversity of information cannot be performed satisfactorily.

By the way, there is another recording medium using a magneto-optical recording material. This type of recording medium has no restrictions on the light source used, and is viewed as promising because it can be rewritten many times. Among these, alloys of rare earth elements such as cci, 'rb, and Dy and iron elements such as Fti and Go are particularly promising as materials for magneto-optical recording.

(Problems to be Solved by the Invention) However, these magneto-optical recording materials are Co-based and Fe-based.
Co-based systems have large changes in magnetic properties due to differences in alloy composition, and are therefore disadvantageous compared to Fe-based systems in terms of increasing their size, while Fe-based systems are highly susceptible to oxidation, which is a practical problem. It has serious drawbacks.

Furthermore, the reality is that many of the conventional optical recording media described above do not necessarily provide satisfactory rewritability and various properties during rewriting as described above.

Accordingly, an object of the present invention is to provide a magneto-optical recording material that has excellent corrosion resistance, good recording stability, and significantly increases the repeatability of writing and erasing. ' Another object of the present invention is to provide a magneto-optical recording material that can be used for high-density recording and has good recording sensitivity.

(Means for solving the problem) In order to achieve this object, the magneto-optical recording material according to the present invention is made of a Fe" RM system alloy, where Fe is iron and R is a rare at least one or two or more elements selected from the group element-based Gd, Tb, and ay, M is a □ metal-based other than the iron and rare earth element-based, and the M includes a layer and Co, The amount of H is 26 to 35 at% of the total amount of the alloy, and the amount of Al is 3 to 35% of the total amount of Fe+M.
The amount of 203-20 atoms Go is 3 out of the total amount of Fe + M
It is characterized in that the content is 20 atomic %.

(Function) The compositional alloy of the present invention contains 1M and Co, and corrosion resistance is significantly improved mainly due to the action of N. This improvement in corrosion resistance also increases recording stability.
The repeatability of writing and erasing will also increase significantly.

Furthermore, due to the poor properties of the compositional alloy itself, the material of this invention is suitable for high-density recording, and the Kerr rotation angle is further increased than that of Co-containing materials, resulting in a higher reproduction S/N ratio. It has the following characteristics.

(Embodiments) Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing an embodiment of an optical/magnetic recording medium using the magneto-optical recording material of the present invention to the extent that its structure can be understood. In the same figure, l is the substrate,
As this substrate 1, a sufficiently smooth and transparent glass substrate or resin substrate is used.

2 is a recording layer extending above the substrate. This recording layer 2 is formed as an alloy layer using the above-mentioned magnetic recording material of the present invention.

For the magneto-optical recording medium formed in this way, 1
Approximately IJL using He-N'e laser light of 0 RAW or less
Perform record writing with writing time of S, approximately IILm
It was confirmed that microrecordings smaller than the diameter were obtained and that it could withstand more than 100,000 erasing and rewriting cycles.

In addition, Fe-R (R+=
A comparative test of corrosion resistance was conducted on a recording medium made of a Tb, Gd, or Dy)-based material and a recording medium formed using the magneto-optical recording material of the present invention. It was confirmed that the recording medium had extremely excellent corrosion resistance. This corrosion resistance will be described below.

in general,? The magneto-optical recording material of this type undergoes pitting corrosion in a high humidity atmosphere, and this pitting corrosion penetrates the thin film. Therefore, as the amount of pitting corrosion increases, the transmittance increases. Therefore,
Corrosion resistance' can be evaluated based on the magnitude of the change in transmittance.

FIG. 2 shows Tb4o among the magneto-optical recording materials of the present invention.
(Al15Co5feqo)7o, Tb3o
(AQ/, Go,, Feg+7)717 or Tb
A magneto-optical recording medium in which the recording layer 2 shown in FIG.
The transmittance of each magneto-optical recording medium is when the magneto-optical recording medium in which the recording layer 2 is formed using 7B or D y30 Fa 70 is maintained in an atmosphere at a temperature of 85° C. and a relative humidity of 85%. FIG. 3 is a characteristic curve diagram showing changes in . Note that 1. is shown in the figure for comparison purposes. T without AQ added
b3. The results of (Go,, Feq, ), are also shown.

In Fig. 2, the retention time of each magneto-optical recording medium in the atmosphere is plotted on the horizontal axis, and the transmittance T after each retention time and the transmittance before being placed in this atmosphere are plotted on the horizontal axis. Transmittance ratio T/T expressed as a ratio to the ratio (referred to as initial value) To
o is plotted on the vertical axis. When the recording layer 2 is not corroded, this transmittance ratio is l, and the greater the amount of corrosion, the larger this ratio becomes.

As can be understood from the experimental results shown in Figure 2, Tb...
(Al15-C0J-Fay, ),,,
↑b,,”(AQ,, Co16 F e7
17) F6 and T bJO (I'l12.Colo
Recording layer 2 using F e'fi6') 70, respectively.
The transmittance ratio of ↑b, , Fs, , Gd, ,
The ratio between Fe, , and 0136 Fe70 is about 1/10 to 4/1000' under the same conditions, and compared to 〒b, , (Go, , Fep, >7.) without M addition, the number is It is less than one-third of that.

Therefore, it can be seen that the magneto-optical recording medium of the present invention has significantly better corrosion resistance than conventional recording media. In addition, ls
Although only the Tb alloy system is shown in Figure 2, the Gd alloy system,
In the Dy alloy system, the effect of adding Al was similar to that in the Tb alloy system.

Next, the Kerr rotation angle of the magneto-optical recording medium of the present invention will be described. It is known that when the Kerr rotation angle is large, the S/N ratio becomes large and the read characteristics are good. While the corrosion resistance increases significantly by adding Al, the Kerr rotation angle decreases, but when the amount of N is 3 to 2
In the range of 0 atomic %, the amount of decrease in the Kerr rotation angle is small, and by adding Go, the decrease in the Kerr rotation angle can be suppressed. Alternatively, this small Kerr rotation angle can be compensated for by applying a dielectric film to the protective layer 2 and utilizing its enhancement effect, so there is no practical problem. The addition does not give the layer any corrosion resistance.

As described above, it has been found that the corrosion resistance of the magneto-optical recording medium of the present invention is significantly improved mainly due to the addition of M, but the cause of this is currently unclear. /IIQ is more chemically active than Fe, and the layer becomes passive in an environment where there is an ionizable metal. Therefore, when the alloy is actively dissolved, the main metal element (Fe
) The more active M becomes a reaction product and is concentrated in a large amount in the corrosion product to form a corrosion product film. The subsequent corrosion progresses by the diffusion of metal ions through this corrosion product film, which acts as a barrier to the progress of corrosion, and therefore, the corrosion resistance of the first alloy is improved.

On the other hand, although Go also has a certain degree of corrosion resistance, this Co
The anticorrosion effect of Go is due to the inactivity of Go, and at the level of content in this invention, its effect is significantly smaller than that of the layer.

Alloys of the above composition range according to the invention, namely: '
F, e -R-M4r gold, Fe is iron, R is Gd
, Tb.

p7, the amount of R is 20 to 35 at% of the entire alloy, M must include M and Go, and the amount of Al is the same as the total amount of F@+M. Among them, 3 to 20 at%, and the amount of Go is Fe+
For magneto-optical recording media using materials with a total M content of 3 to 20j%, conventional Fe-R system (R=Gd,
In addition to having the same characteristics as the optical m% recording medium using at least one of Tb or ay),
It was confirmed that the corrosion resistance was significantly improved, the recording stability was improved, and the repeatability of writing and erasing was significantly increased compared to the conventional case. In addition, the amount of Co is 3 to 20 at%
The reason for this is to prevent the addition of Co, since although the Kerr rotation angle can be increased, the Curie point increases rapidly, and excessive addition reduces the magneto-optical recording sensitivity. If it is within this range, it will be an appropriate Curie point value, and
It is possible to suppress the decrease in the Kerr rotation angle due to the addition of M.

In addition, the amount of R is set to 20 to 35 atomic% of the entire alloy.
However, this is done in consideration of the fact that a perpendicularly magnetized film is easily obtained. Such a magneto-optical recording material according to the present invention is not only applied to the above-mentioned transparent glass, but also can be applied in any desired shape, whether transparent or opaque, in the form of a plate, sheet, tape, or the like. It can be deposited as an alloy layer on a substrate made of the material.

(Effects of the Invention) As is clear from the above, since the magneto-optical recording material according to the present invention contains AQ and Go,
It has better corrosion resistance than conventional recording materials of this type.
It has the advantage of good recording stability and can significantly increase the repeatability of writing and erasing, and also has the advantage of enabling high-density recording due to the characteristics of the material itself and having good recording sensitivity.

Further, the magneto-optical recording material of the present invention can be written and erased using a laser beam, and has the advantage that various conventional restrictions regarding the light source used are significantly alleviated.

The magneto-optical recording material of the present invention is particularly suitable for use in recording media.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing a magneto-optical recording medium formed by applying the magneto-optical recording material of the present invention, and FIG. 2 is a light transmission diagram showing the characteristics and explanation of the magneto-optical recording material of the present invention. It is a curve diagram showing experimental results of gravity ratio. l...Substrate, 2...Recording layer.

Claims (1)

[Claims] Fe-R-M alloy, Fe is iron, R is at least one or more elements selected from rare earth elements Gd, Tb, and Dy, and M is an element other than iron and rare earth elements. The alloy is metal-based, the M includes Al and Co, the amount of R is 20 to 35 at% of the total amount of the alloy, and the amount of Al is 3 to 20 at% of the total amount of Fe + M, The amount of Co is 3 to 20 of the total amount of Fe+M.
A magneto-optical recording material characterized in that it is expressed as atomic %.