JPS6331048A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To provide the higher performance than the performance of the conventional recording media to a recording medium to be used for a magneto-optical recording system by incorporating light rare earth metals and >=2 kinds among Zr, B, Si, Al, Cr, Sn, Pb, and Bi inclusive always of Zr in addition to heavy rare earth metals and transition metals into said medium. CONSTITUTION:An amorphous alloy which is constituted of >=1 kinds among the light rare earth metals Sn, Nd, Pr, Ce, and Eu, >=1 kinds among the heavy rare earth metals Tb, Gd, and Dy, >=1 kinds among the transition metals Fe, Co, and Ni and 2 >= kinds of the elements among Zr, B, Si, Al, Cr, Sn, Pb, and Bi inclusive always of Zr and contains these elements within the ranges of 0.1<=x<=0.4, 0.1<=y<=0.5, 0<=z<=0.2 when the compsn. formula is (LRxHR1-x) yTM1-y-zAz is used for the recording medium which is formed on a substrate and can record, reproduced and erase information by light. The light rare earth metals and Zr in addition to the heavy rare earth metals and the transition metals are thereby incorporated into the recording medium; therefore, the manufacutre of an alloy target by melting and casting is possible and further, the magneto-optical characteristics are improved by the addition of the other elements.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magneto-optical S6 recording medium that can be recorded, reproduced, and erased by, for example, irradiation with laser light or the like.

[Conventional technology]

While heating the recording layer with a laser beam spot, recording is performed by applying an external magnetic field to form reversed magnetic domains.The laser beam spot, which is linearly polarized and has a lower power than during recording, is incident on the recording layer to generate the Kerr effect or Faraday effect. A recording system used in the so-called magneto-optical recording method, in which reproduction is carried out using the magnetic field, must satisfy at least the following properties.

1. The Curie temperature is low enough to allow recording and erasing with a semiconductor laser, and the Curie temperature is sufficiently high compared to the normal usage environment temperature.

2 To avoid grain boundary noise that occurs when the recording medium is polycrystalline, and manufacturing difficulties that occur when the recording medium is single crystal,
The recording medium must be amorphous. In this case, it is necessary that the crystallization temperature is sufficiently higher than the Curie temperature.

5. Since regeneration utilizes the Kerr effect and Faraday effect, the Kerr rotation angle and Faraday rotation angle caused by the above effects must be large.

4. It is a perpendicular magnetization film. Therefore, conventionally TbFe, TbFeCo, GdTb
Materials such as FsCo have been used as magneto-optical recording media as they satisfy the above properties.

Furthermore, heavy rare earth metals Tb, Gd, D7. By adding a light rare earth metal Sm to a transition metal F, optical reproduction characteristics have been improved without impairing recording characteristics. [Problems to be developed by the invention] Magneto-optical recording media are Since it is necessary to be amorphous, a vapor phase rapid cooling method such as sputtering or vapor deposition is used as a manufacturing method.

However, it is difficult to produce by melting and casting an alloy having approximately the same composition as the heavy rare earth-transition metal amorphous alloy used as a magneto-optical recording medium because these alloys are easily cracked. Therefore, when producing a recording medium by sputtering, it is not possible to produce a recording medium from a single target. 200762, JP-A-59-208815
An embedded composite target such as a force (force) must be used.

Rare earth metal Nupanta targets are usually produced by melting and casting, but with this method it is difficult to suppress the oxygen contained in the target to less than 1 liter 1 weight percent. Therefore, there is a drawback that oxygen contained in the sputtering target or the evaporation source mixes into the recording medium and dissolves its magnetic properties.

The present invention solves these problems, and in addition to heavy rare earth metals and transition metals, light rare earth metals, Zr, B,
By including two or more of Sj, At, Cr, Sn, Pb, and Bi, which always contain Zr, it is possible to provide a magneto-optical recording medium with higher performance than conventional ones.

[Means for solving problems]

The magneto-optical recording medium of the present invention is formed on a substrate.

Light rare earth metals JI4 Sn, Nd, Pr, Cm,
One or more types of In, heavy rare earth metals Tb, cd, D
one or more of y, one or more of transition metals Fe, Co, and Ni, and Zr, B, 81. A.L., C.
r, So.

It is composed of two or more elements, including Pb and Bi, which always include Zr.

When the compositional formula is (LRxHRs-x)yTM+-y-zAz, (LR is one or more of the above-mentioned light rare earth metals, HR is one or more of the above-mentioned heavy rare earth metals, TM is the above-mentioned transition One or more metals, A is Zr, B,
31. In the present invention, X satisfies α1≦X≦α4. α1≦y≦[L5. O≦2≦12.

X is more preferably 111≦X≦α3. y is more preferably α15≦y≦(15, z is more preferably CLfl
l≦2≦α1. Also, I is most preferably α2≦X
≦IIS.

y is preferably CL18≦y≦αS, Z is more preferably (L3≦2≦α08), and as a person, preferably Zr and B, more preferably Zr and person t. Also, most preferred are Zr and Bi.

[Example 1] The effects of the present invention will be described with reference to Examples.

The magneto-optical recording medium of the present invention was manufactured by sputtering. Unlike conventional methods, we used melted and cast alloys as targets to produce these. Table 1 shows the correspondence between target composition and sample number.

Table 1 Table 2 shows the analysis results of oxygen concentration in these alloy targets.
Shown below.

Table 2 As shown in Table 2, the oxygen concentration in the target was α005% or less by weight. After casting the target, slag remains in the melting furnace, and it is thought that the oxygen in the rare earth metal or transition metal is incorporated into this slag.

In this way, in the alloy target formed by melting and n-forming, the oxygen concentration contained therein can be extremely reduced.

In addition, the alloy shown in Example 1? Denka, Zr and 31,
Targets made of alloys containing Zr and Cr and Zr and Sn were prepared, and the ease of forming the alloy targets and the oxygen concentration were almost the same.

[Example 2] As described in Example 1, changes in the Kerr rotation angle of a magneto-optical recording medium produced by sputtering with varying amounts of Bi and Sn using an alloy target produced by melting and casting. The results of the investigation are shown in Figure 1.

An increase in the Kerr rotation angle was observed with the addition of Sn, Pb, Bi, and At.

[Example 3] In order to investigate the recording/reproducing characteristics of the magneto-optical recording medium 2 of the present invention and the conventional example, approximately
50^ magneto-optical recording media were respectively formed, and about 1000 aluminum nitride layers were formed thereon.

Recording and playback were performed under the following conditions.

Recording between grooves, reproducing power 1 mW, recording magnetic field 5000 @, linear velocity 4.7 per second. ,, recording frequency IMH2, resolution band 3
It is 0KH2.

FIG. 2 shows the magneto-optical recording medium of the present invention ((Nd&5I)yOj92M (F@OJ@(o
6.4su・ys (zy+, sS1+, zggo, ze
Loss and FIG. 3 show the conventional example Tb@J (F・o, 5C
Recording laser power and C7N ratio of 6t68, and 2
The relationship between harmonic suppression ratios is shown. In the magneto-optical recording medium of the present invention, it was found that the C/N ratio was improved and the recording laser power was reduced compared to the conventional example.

As is well known, the laser power during recording on the recording surface of a magneto-optical recording medium is proportional to the square root of the linear velocity of the recording surface, so in order to increase the transfer rate of recorded information, it is desirable that the recording laser power be lower. .

Therefore, it can be said that the magneto-optical recording medium of the present invention has improved both recording and reproducing characteristics compared to the conventional example.

After all, in the conventional TbFeCo magneto-optical recording medium.

It was fabricated by conventional sputtering using a composite target.

〔Effect of the invention〕

As described above, the magneto-optical recording medium of the present invention has the advantage that, in addition to heavy rare earth metals and transition metals, it is possible to manufacture alloy targets containing light rare earth metals and Zr by licking, melting, and casting. Furthermore, it also has the effect of improving magneto-optical properties with other additive elements.

[Brief explanation of drawings]

In FIG. 1, (Nd6jTbOsuo,xt(F@o
,5sC6o4su0.7m(Zr+-zXz)...,X=
Kerr rotation angle of S n, B t, P b, At and 2
Figure 2 shows the relationship between... of the present invention ((Hdo, sDy eγ
(p60.61(06,4s0.?j(zr6JS1
6J1] 3ej... is a diagram showing the relationship between the C/N ratio, the second harmonic suppression ratio, and the recording laser power. Fig. 3... Conventional example Tb++-v(Feo, *C0a
I) Relationship between C7N ratio and second harmonic suppression ratio of o and a and recording laser power? Figure shown. Applicant: Seiko Epson Corporation x X=Sy-,0X=AL X-8i o o, or
o,t. (IVJ,, 1α3 Th o, q) o, :n (Fa
asrCo osr)oss (k+ -x Xx)o
, or mark X Figure 1 0 2 4 9gIQ Name 2 Figure 3

Claims (1)

[Claims] A recording medium formed on a substrate and capable of recording, reproducing, and erasing information using light rare earth metals Sn, Nd, Pr,
One or more of Co, Eu, heavy rare earth metals Tb, Gd
, one or more of the transition metals Fe, Co, and Ni, and one or more of the transition metals Fe, Co, and Ni, and Zr, B, Si, Al, Cr, and S.
It is composed of two or more elements that always include Zr among n, Pb, and Bi, and the composition formula is (LR_xHR_1_-_x).
It is characterized by using an amorphous alloy in the range of 0.1≦x≦0.4 0.1≦y≦0.5 0≦z≦0.2 when expressed as _yTM_1_−_y_−_zA_z Magneto-optical recording medium. (However, LR is one or more of the above light rare earth metals,
HR is one or more of the heavy rare earth metals listed above, TM is one or more of the transition metals listed above, and A is Zr, B, S.
i, Al, Cr, Sn, Pb, and Bi, which represent two or more elements that always include Zr.