JP2911293B2 - Magneto-optical recording medium - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-optical recording medium, and more particularly, to an underlayer sandwiched between a transparent substrate and an alternately laminated film composed of a layer containing platinum and a layer containing a transition metal.

[0002]

2. Description of the Related Art FIG. 2A shows a platinum / cobalt laminated film (P).
1 shows a conventional magneto-optical recording medium using a (t / Co laminated film). A dielectric film such as SiN is formed on the glass or polycarbonate (PC) substrate 3 to increase the Kerr effect, and then an etching process is performed to smooth the SiN. Then, platinum and cobalt are laminated by several square meters (first
4th Annual Meeting of the Japan Society of Applied Magnetics 65).

However, in such a film configuration, since SiN is amorphous and the platinum layer is not stacked in the [111] direction, the perpendicular magnetic anisotropy is small, and the coercive force required for high density recording is about 1 KOe. I can only get it. FIG. 2B shows another conventional magneto-optical recording medium. In this case, GaAs (111) or Pt (111) is
It was reported that the coercive force increased to 4 KOe when cobalt was laminated (E-MRS spring'90 C 8
However, since GaAs and Pt are opaque, signals cannot be read if such an underlayer is provided.

[0004]

As described above, in a magneto-optical recording medium using a platinum / cobalt laminated film, a coercive force required for high-density recording cannot be obtained or a signal cannot be read. .

[0005]

Means for Solving the Problems A transparent underlayer compound having a corundum Al ₂ O ₃ type structure is sandwiched between an alternately laminated film composed of a layer containing platinum and a layer containing a transition metal, and a transparent substrate. . Alternatively, Al _{2 is} used as the underlayer compound.
O ₃ is used.

[0006]

The compound having a corundum Al ₂ O ₃ type structure is [000
When viewed from the [1] direction, the arrangement is similar to that when viewed from the Pt [111] direction. The interatomic distance between oxygen atoms such as Al ₂ O ₃ is substantially equal to that of platinum. Therefore,
Prior to stacking platinum, the films of these compounds were plated with platinum [11].
1] If the films are formed so as to be similar in arrangement when viewed from the direction, platinum is also arranged densely from the beginning of the film formation. Therefore, the coercive force of the alternately laminated film including the layer containing platinum and the layer containing the transition metal increases, and high-density recording becomes possible. Further, since it is transparent, signals can be reproduced, and by appropriately adjusting the film thickness, the Kerr rotation angle increases.

[0007]

An example of the embodiment of the present invention, platinum / cobalt multilayer film magnetic layer, will be described using the Al ₂ O ₃ (sapphire) the underlying compound. FIG. 1 is a sectional structural view of a magneto-optical recording medium according to the present invention, in which Al ₂ O ₃ 1 is formed on a transparent substrate 3 and a platinum / cobalt laminated film 2 is formed thereon.

FIG. 3A is a crystal structure diagram of platinum, and FIG. 3B is a structure diagram showing a state of stacking viewed from the [111] direction. The platinum crystal has a face-centered cubic lattice as shown in FIG. 3A, and when viewed from the [111] direction, FIG.
Make the stack as close as possible. The lattice constant is 3.9Å,
The interatomic distance is 2.8 °. When the arrangement of the atoms on the surface of the underlayer is similar to the surface of the platinum viewed from the [111] direction, the crystallinity of the platinum is improved.

FIG. 4 is a structural diagram showing the crystal structure of corundum Al ₂ O ₃ type. Sapphire (Al ₂ O ₃ ) has a corundum Al ₂ O ₃ type structure and, when viewed from the [0001] direction, has a platinum [111] structure. ] Is similar to the plane viewed from the direction. FIG. 5 is a plane crystal structure diagram of the sapphire C plane (0001). The average distance between oxygen in the sapphire C plane is 2.
75 °, while the interatomic distance of platinum is about 2.8.
Since Å, mismatch between lattices is small. Therefore, when sapphire is used as a base layer and platinum is stacked thereon, platinum is also stacked in a dense structure.

FIG. 6A shows that the surface of the underlayer is made of platinum [11].
1] is a state diagram of the interface between platinum and an underlayer when the surface is significantly different from the surface viewed from the [1] direction. FIG. 6B is a state diagram of the interface of the underlayer when the surface of the underlayer is similar to the surface of platinum as viewed from the [111] direction. In the figure, 4 is a platinum atom, and 5 is an atom of the underlayer. In FIG. 6B, platinum is stacked in the closest arrangement. As described above, the crystallinity of platinum is improved and the coercive force of the platinum / cobalt laminated film is increased by using the underlayer in which atoms are arranged in a manner similar to that of platinum.

[0011]

As described above, transparent and corundum Al
By using an underlayer of a compound having a ₂ O ₃ type structure, the crystallinity of platinum is improved, and the coercive force of an alternately stacked film including a layer containing platinum and a layer containing a transition metal is increased. As a result, high density recording becomes possible.

[Brief description of the drawings]

FIG. 1 is a sectional structural view of a magneto-optical recording medium of the present invention.

FIG. 2A shows a conventional magneto-optical recording medium using a platinum / cobalt laminated film (Pt / Co laminated film). (B) Another conventional magneto-optical recording medium.

FIG. 3 (a) is a crystal structure diagram of platinum. (B) is a structural diagram showing a state of stacking viewed from the [111] direction.

FIG. 4 is a structural diagram showing a crystal structure of a corundum Al ₂ O ₃ type.

FIG. 5 is a plane crystal structure diagram of a sapphire C-plane (0001).

FIG. 6 (a) is a state diagram of the interface between platinum and the underlayer when the surface of the underlayer is significantly different from the surface of the platinum viewed from the [111] direction. (B) A state diagram of the interface of the underlayer when the surface of the underlayer is similar to the surface of platinum as viewed from the [111] direction.

[Description of Signs] 1 Al ₂ O ₃ 2 Platinum / Cobalt laminated film 3 Transparent substrate

Claims (3)

(57) [Claims] 1. An alternate laminated film composed of a layer containing platinum and a layer containing a transition metal, a transparent substrate, and a transparent and corundum A sandwiched between the alternately laminated film and the transparent substrate.
A magneto-optical recording medium comprising an underlayer of a compound having an l ₂ O ₃ type structure. 2. The method according to claim 1, wherein the underlayer of the compound is in contact with the alternately laminated film.
And the alternate product with the [0001] direction, which is the crystal direction of the underlayer.
Magneto-optical recording characterized in that the laminating direction of the layer film coincides
Recording medium. (3) In claim 1 or 2, The underlayer is made of Al _Two O _Three Magneto-optical recording characterized by being
Recording medium.