JPH01130348A - magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To allow microbits to exist stably and to attain good reproduction by laminating a light transparent soft magnetic material, magnetoplumbite type oxide magnetic material and soft magnetic material of an alloy system consisting of any selected from NiFe, CoNbZr and NiP successively on a transparent substrate. CONSTITUTION:The light transparent soft magnetic material 2, a recording layer 3 consisting of the magnetoplumbite type oxide magnetic material and the soft magnetic material layer 4 consisting of the alloy system selected from the NiFe, CoNbZr and NiP are successively laminated on the transparent substrate 1. Namely, this recording medium is constituted by forming the chemically stable magnetoplumbite type oxide magnetic material as the recording layer 3 and sandwiching this recording layer 3 from above and below by the soft magnetic materials 2, 4. Diamagnetic fields are thereby decreased and the microbits are made to exist stably; in addition, the rotating angle in a satd. state can be utilized, the good reproduction is possible.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a magneto-optical recording medium using a magnetoplumbite type oxide magnetic material as a recording layer.

[Prior art]

Generally, oxide magnetic materials such as rare earth-transition metal alloys, magnetoplumbite type oxide magnetic materials, and spinel ferrite have been proposed as the recording layer of magneto-optical recording media.

Among these, when a rare earth-transition metal alloy is used as a recording layer,
Since the M-H loop of this alloy has a squareness ratio (Mr/Ms) of 1 as shown in Figure 2, all magnetic domains are completely reversed even in the residual magnetization state as shown in Figure 3. The recording bits are aligned upward (or downward), and the minute recording bits exist stably.

On the other hand, when a magnetoplumbite type oxide magnetic material is used, for example, BaFe1□Co@asTi is deposited on a GGG substrate.
As shown in Fig. 4, the M-H)Ll-p which formed the a-soas film is tilted by 1 demagnetizing field 4πMs, and when the magnetic field is 0 (residual magnetization state), it is tilted upward with respect to the film surface. and downward magnetic domains are mixed. That is, as shown in FIG. 5, since the inverted magnetic domain exists within the recording magnetic domain or around the recording magnetic domain, the minute bits are stably present,
Moreover, it was difficult to obtain good reproduction.

In this way, rare earth-transition metal alloys are superior to magnetoplumpite-type oxide magnetic materials in order to obtain stable microbits, but these rare earth-transition metal alloys tend to change over time due to oxidative corrosion and have high The problem is that reliable magneto-optical recording media are difficult to obtain.

〔the purpose〕

Therefore, the present invention solves the above-mentioned problems that occur when a recording layer is made of magnetoplumbite-type oxide magnetic material, which is chemically stable because it is an oxide itself, and allows minute bits to exist stably. The object of the present invention is to provide a magneto-optical recording medium that provides good reproduction.

〔composition〕

The magneto-optical recording medium of the present invention has a transparent soft magnetic material, a magnetoplumbite type oxide magnetic material, and a NiF
It is characterized by sequentially laminating alloy-based soft magnetic materials selected from e, CoNbZr, and NiP.

FIG. 1 shows an embodiment of a magneto-optical recording medium according to the present invention. In FIG. 1, 1 is a transparent substrate such as quartz glass, and on this transparent substrate 1 is a transparent soft magnetic layer 2.
．． A recording layer 3 made of a magnetoplumbite type oxide magnetic material and an alloy-based soft magnetic material layer 4 selected from NiFe and CoNbZr*NiP are sequentially laminated.

Normally, magneto-optical recording media are irradiated with laser light from the substrate side.
In order to perform recording and reproduction, the soft magnetic layer 2 provided on the substrate 1 side in the present invention is transparent to laser light (7g0ni+, 830 nm) such as NiZn ferrite or MnZn ferrite (with a film thickness of 0.3 ptrr). (transmittance of 80% or more) oxide-based soft magnetic material. The transparent soft magnetic layer 2 has a thickness of 0.05 to 1.0 μm, preferably 0.1 μm.
~0.3 μm. In addition.

This light-transmitting soft magnetic material layer 2 also has the role of a base layer of the magnetoplumbite-type oxide magnetic material laminated thereon, and the magnetoplumbite-type oxide magnetic material has a good C.
A perpendicular magnetization film with axial orientation can be obtained.

On this transparent soft magnetic layer 2, a magnetoplumbite type oxide magnetic material is formed as a recording layer 3 with a thickness of 0 as a perpendicularly magnetized film.
．． A film with a thickness of 1 to 1 μm is formed. This magnetoplumbite type oxide magnetic material is M-Feixons (M is Sr, Pb
, Ba).

Here, to give a specific example, Ni, 2Zn on quartz glass
,,,After forming Fe,04, BaFe1tC1)+-5TX,,
Using a target having a composition of SO, , Ar
+ The substrate temperature was heated to about 620°C in an atmosphere of BaFe1. Co00. A recording layer consisting of Ti, ++, O, . . . was formed to a thickness of 0.3 μm.

The alloy-based soft magnetic material layer 4 laminated on this recording layer 3 is made of Ni
One selected from Fe, CoNbZr, and NiP. Since this alloy-based soft magnetic layer 4 is selected from the above-mentioned materials, it acts as a reflective layer, and its thickness is 0.
．． The range is 0.05 to 0.3 μm.

Typically, the recording layer is Hk/4 x Ms>10 (Hk:
In the case of a heterogeneous magnetic field (Ms: saturation magnetization), a recording medium with a squareness ratio of ":1" can be obtained, but in the case of a magnetoplumbite-type oxide magnetic material, Hk/4πM g = about 3,6. Therefore, the 5M-H loop is tilted by 4πMs due to the demagnetizing field (4πMs), and the squareness ratio is not 1°; As shown in Figure 6, a closed loop is formed between the recording magnetic domain and the soft magnetic layer, and the demagnetizing field is canceled, as shown in Figure 1. In this way, a minute bit is formed by a completely reversed magnetic domain, and the existence of a reversed magnetic domain within a recording magnetic domain is prevented.

〔effect〕

According to the present invention as described above, a chemically stable magnetoplumbite type oxide magnetic material is used as a recording layer, and this recording layer is sandwiched between upper and lower sides by soft magnetic materials, so that 1 demagnetizing field is reduced. This has the effect that good reproduction can be expected because the minute bits can be stably present and the rotation angle in the saturated state can be used.

[Brief explanation of the drawing]

FIG. 1 is a partial perspective explanatory view showing one embodiment of the present invention. FIG. 2 is an M-H loop diagram in a rare earth-transition metal alloy. FIG. 3 is a partial perspective explanatory view of a magneto-optical recording medium using the recording layer shown in FIG. 2. FIG. FIG. 4 is an MH loop diagram in a magnetoplumbite type oxide magnetic material. FIG. 5 is a partial perspective explanatory view of a magneto-optical recording medium using the recording layer of FIG. 4. FIG. FIG. 6 is an explanatory diagram showing recording magnetic domains in the embodiment of the present invention shown in FIG. 1. 1...Transparent substrate 2...Transparent soft magnetic material layer 3...Recording layer 4...Alloy-based soft magnetic material layer box 1 (!l 爾4(￥1) Figure 3

Claims (1)

[Claims] 1. In a magneto-optical recording medium using a magnetoplumbite-type oxide magnetic material as a recording layer, a transparent substrate is coated with a transparent soft magnetic material, a magnetoplumbite-type oxide magnetic material, and a material selected from NiFe, CoNbZr, and NiP. 1. A magneto-optical recording medium characterized by sequentially laminating any one of the alloy-based soft magnetic materials.