JPH06325419A - Magneto-optical recording medium - Google Patents

Abstract

PURPOSE:To obtain a satisfactory magneto-optical recording medium having a large angle of Kerr rotation and high perpendicular magnetic anisotropy by disposing an artificial lattice film formed by alternately laminating prescribed metallic layers. CONSTITUTION:When a dielectric layer 2, an artificial lattice film 3, a dielectric layer 4 and a reflecting film 5 are laminated on a transparent substrate 1 to obtain a magneto-optical recording medium, the film 3 is formed by grouping a Co layer of 1-5Angstrom thickness, an Ni layer of 1-8Angstrom thickness and a Pt layer of 4-20Angstrom thickness and laminating plural such groups. The objective magneto- optical recording medium capable of maintaining a large angle of Kerr rotation in a short wavelength region peculiar to a Co/Pt artificial lattice and having a moderate Curie temp. and high perpendicular magnetic anisotropy is obtd.

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 for recording, reproducing and erasing information by using light.

[0002]

2. Description of the Related Art As one of means for increasing the density of a magneto-optical recording medium, there is a method of using a light source of short wavelength for recording / reproducing. As a medium used in such a method, a large magneto-optical effect is obtained in a short wavelength region. , A magneto-optical recording medium using an artificial lattice film in which Co layers and Pt layers are alternately laminated has been proposed. However, a film used for such a medium has a problem that the Curie temperature is high in a composition region showing a large Kerr rotation angle, the recording power is increased and the durability of the medium is lowered.

In order to solve this problem, an artificial lattice film composed of Co alloy and Pt obtained by adding a third component to the Co layer has been studied (Hashimoto, Ochiai, 1990 Japan Society for Applied Magnetics Science). Summary page 67).

However, the artificial lattice film formed by adding such a third component has a problem that although the Curie temperature is lowered to some extent, the perpendicular magnetic anisotropy is also lowered with the decrease.

[0005]

An object of the present invention is to obtain good magneto-optical recording / reproducing characteristics using an artificial lattice film having a large perpendicular magnetic anisotropy, a large Kerr rotation angle, and an appropriate Curie temperature. Another object is to provide a magneto-optical recording medium having the same.

[0006]

Means for Solving the Problems As a result of intensive studies conducted by the present inventors in view of the above points, a plurality of artificial lattice films having three layers of Co, Ni, and Pt (one lamination period) are formed. It has been found that the laminated films can lower the Curie temperature while maintaining good perpendicular magnetic anisotropy and a large Kerr rotation angle.

That is, according to the present invention, at least the information recording / reading layer comprises three layers of Co layer, Ni layer and Pt layer as one set,
The present invention relates to a magneto-optical recording medium comprising a plurality of artificial lattice films laminated. Hereinafter, the present invention will be described in more detail.

The present invention is based on the above-mentioned Co, Ni and Pt 3
It is characterized in that it is made of an artificial lattice film having a layered structure, but the layer thickness of each layer is 1 to 5 A for the Co layer, 1 to 8 A for the Ni layer,
The Pt layer is preferably in the range of 4 to 20A. Even if the thickness of each layer is changed outside the above range, for example, the Co layer thickness is 5 A
When the thickness is thicker, the Curie temperature of the laminated film becomes too high, and when the thickness of the Ni layer is thicker than 8 A, the perpendicular magnetic anisotropy, in other words, the coercive force is lowered, and it becomes difficult to record a minute bit. On the other hand, if the Pt layer thickness exceeds 20 A, the Kerr rotation angle is insufficient, and if it is less than 4 A, good recording / reproducing characteristics cannot be obtained due to a decrease in squareness ratio and an increase in Curie temperature. Can't get to.

The present invention will now be further described with reference to the drawings. FIG. 1 shows a sectional view of one embodiment of the present invention. In the figure, 1 is a transparent substrate, which is usually made of glass or a polymer material. Reference numeral 2 is a dielectric layer for enhancing the magneto-optical effect due to the interference effect of light, and is usually made of SiN, SiO, ZnS, ZnO or the like. Reference numeral 3 is an artificial lattice film that characterizes the present invention, and at least two sets (2 sets) each including three layers of Co layer, Ni layer, and Pt layer
Cycle) stacked.

In this case, the order of stacking the Co layer, the Ni layer and the Pt layer is not particularly limited, and the order of stacking each layer in each set (cycle) may not be the same. However, it is sufficient that at least these three layers are configured as one set (one cycle), and the metals of the same type are not stacked in an overlapping state. The total thickness of this artificial lattice film is 50 to 30.
It is about 0 angstrom.

Reference numeral 4 is a dielectric layer typified by SiN, SiO, ZnS, ZnO and the like, and 5 is a reflective film layer in which an alloy containing Al as a main component is usually used. The thickness of each layer other than the above-mentioned artificial lattice film is appropriately determined according to recording / reproducing conditions such as the wavelength of light used.

The method of laminating each layer on the substrate of the present invention is not particularly limited, but a usual thin film forming method such as a sputtering method or a vacuum deposition method can be used, and the conditions therefor are not particularly limited. Further, the artificial lattice film can be magnetically coupled to a rare earth transition metal film or other magnetic film for the purpose of overwriting. In this case, the artificial lattice film constituting the present invention functions as an information recording / reading layer.

[0013]

EXAMPLES Next, the present invention will be described in more detail with reference to Examples.

Example As shown in Table 1, Co, Ni, and Pt layer thicknesses were controlled so that the car rotation angles were almost the same, and Co / Ni / Pt artificial materials having the compositions shown in a to c of the table were prepared. Formed a grid. For comparison, the conventional Co / Pt and C are shown in d and e of Table 2.
The characteristics of the o50Ni50 / Pt artificial lattice are shown. a-d
The sample of Co., Co, Ni, and Pt are simultaneously sputtered on three targets, and the substrate is Co, N
An artificial lattice film was prepared by rotating so as to pass i and Pt in this order.

For e, a Co50Ni50 alloy and a Pt simple substance target were simultaneously sputtered, and an artificial lattice film was formed by rotating the substrate so as to alternately pass over each target. For all samples, DC magnetron sputtering was used for the ferromagnetic material and RF magnetron sputtering was used for Pt to form a film on the glass substrate, and the total film thickness was unified to about 200 angstroms.

Each of the artificial lattice layers having the film structures shown in Tables 1 and 2 has a saturation magnetization of about 350 emu / cc and a Kerr rotation angle of about 0.3 degree for 400 nm light, and has substantially the same magnetic and magneto-optical properties at room temperature. Characterized.

From the results shown in the table, the artificial lattice film of the present invention shows a large coercive force while having a lower Curie temperature than the Co / Pt artificial lattice film having the same Kerr rotation angle as the conventional film. I understand. Further, it has a Curie temperature almost the same as that of the artificial lattice film composed of the CoNi alloy layer and the Pt layer, and shows a large coercive force.

As described above, it is possible to reduce the Curie temperature and improve the coercive force of the conventional Co / Pt artificial lattice film by forming the artificial lattice film in which the Co layer, the Ni layer and the Pt layer are sequentially laminated. it can.

[0019]

[Table 1]

[0020]

[Table 2]

[0021]

The recording medium of the present invention similarly retains the large Kerr rotation angle in the short wavelength region of the Co / Pt artificial lattice, and further has an appropriate Curie temperature and a large perpendicular magnetic anisotropy. It is a magnetic recording medium and can be expected to have good recording and reproducing characteristics.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section of an embodiment of the present invention.

[Explanation of symbols]

1: Transparent substrate 2: Dielectric layer 3: Artificial lattice film consisting of alternating layers of Co layer, Ni layer and Pt layer 4: Dielectric layer 5: Reflective film

[Procedure amendment]

[Submission date] June 2, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

Example As shown in Table 1, Co, Ni, and Pt layer thicknesses were controlled so that the car rotation angles were almost the same, and Co / Ni / Pt artificial materials having the compositions shown in a to c of the table were prepared. Formed a grid. For comparison, the conventional Co / Pt and C are shown in d and e of Table 2.
The characteristics of the o50Ni50 / Pt artificial lattice are shown. a-d
The sample of Co., Co, Ni, and Pt are simultaneously sputtered on three targets, and the substrate is Co, N
i, was created artificial <br/> lattice film by rotating so as to pass in the order of Pt.

Claims (2)

[Claims] 1. A magneto-optical recording medium, wherein at least the information recording / reading layer comprises an artificial lattice film in which a plurality of sets of three layers of a Co layer, a Ni layer and a Pt layer are laminated. 2. The magneto-optical recording medium according to claim 1, wherein the Co layer has a thickness of 1 to 5 angstroms, the Ni layer has a thickness of 1 to 8 angstroms, and the Pt layer has a thickness of 4 to 20 angstroms.