JP2608193B2 - Magneto-optical storage element - 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 storage element for recording, erasing and reproducing information with light such as laser light.

[0002]

2. Description of the Related Art A Pt / Co multilayer film in which a Pt layer and a Co layer are alternately and repeatedly laminated has only a perpendicular magnetic anisotropy as disclosed in Japanese Patent Application Laid-Open No. 2-263344. Rather, it has a larger Kerr rotation angle with respect to short wavelength light than the rare earth-transition metal alloy. For this reason,
2. Description of the Related Art A magneto-optical storage element using a Pt / Co multilayer film has attracted attention as a magneto-optical recording medium capable of high density magneto-optical recording.

[0003]

However, in the above-mentioned conventional configuration, "IEEE TRANSACTIONS ONM
AGNETICS, Vol. 25, No. 5, p. 3764, the film thickness ratio between the Pt layer and the Co layer of the Pt / Co multilayer film, that is, (film thickness of Pt layer / film of Co layer). When the thickness is increased, the perpendicular magnetic anisotropy increases, but the Kerr rotation angle decreases. Therefore, Pt / C having a large perpendicular magnetic anisotropy and a large Kerr rotation angle
o There is a problem that it is difficult to obtain a magneto-optical storage element using a multilayer film.

[0004]

According to the present invention, there is provided a magneto-optical memory device having a Pt / Co multilayer film in which a Pt layer and a Co layer are alternately and repeatedly laminated on a substrate. The thickness ratio between the adjacent Pt layer and the Co layer formed on the substrate is set to be larger than the thickness ratio between the adjacent Pt layer and the Co layer formed on the far side from the substrate. And

[0005]

According to the above construction, in a magneto-optical memory device having a Pt / Co multilayer film in which a Pt layer and a Co layer are alternately and repeatedly laminated on a substrate, an adjacent Pt layer formed on a side close to the substrate is provided. And the thickness of the Co layer are set to be larger than the thickness ratio of the adjacent Pt layer and the Co layer formed on the side farther from the substrate, so that the side closer to the substrate is closer to the side farther from the substrate. A Pt / Co multilayer film having a relatively large perpendicular magnetic anisotropy and exhibiting a greater Kerr effect on the side farther from the substrate than on the side closer to the substrate is formed. For this reason,
By causing light to enter from the side of the Pt / Co multilayer film having a large Kerr effect, a large Kerr rotation angle can be obtained. Also, P
Since the t / Co multilayer film has a larger perpendicular magnetic anisotropy on the side closer to the substrate than on the side farther from the substrate, the magnetization is perpendicular to the Pt / Co multilayer film even on the side farther from the substrate. It is more stable to face in a different direction. Therefore, the perpendicular magnetic anisotropy increases even on the side far from the substrate. Thereby, a magneto-optical storage element having a large perpendicular magnetic anisotropy and a large Kerr rotation angle can be obtained.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG.

As shown in FIG. 1, the magneto-optical storage element of this embodiment includes a substrate 1 made of glass or a resin such as polycarbonate, and a first Pt / C formed on the substrate 1.
o It mainly includes a multilayer film 2 and a second Pt / Co multilayer film 3 formed on the first Pt / Co multilayer film 2.

[0008] The first Pt / Co multilayer film 2 is composed of a Pt layer 2a.
And the Co layer 2b are alternately and repeatedly laminated, and the second Pt / Co multilayer film 3 is composed of the Pt layer 3a and the Co layer 2b.
The layer 3b is alternately and repeatedly laminated.

The thickness ratio of the Pt layer 2a and the Co layer 2b in the first Pt / Co multilayer film 2, that is, (the thickness of the Pt layer 2a / the thickness of the Co layer 2b) is the second Pt / Co The thickness is set to be larger than the thickness ratio of the Pt layer 3a and the Co layer 3b in the multilayer film 3, that is, (thickness of the Pt layer 3a / thickness of the Co layer 3b). Thus, the first Pt / Co multilayer film 2 having a larger perpendicular magnetic anisotropy than the second Pt / Co multilayer film 3 is disposed on the substrate 1 side.
On the other side, a second Pt / Co multilayer film 3 having a larger Kerr effect than the first Pt / Co multilayer film 2 is arranged.

Specifically, for example, the thicknesses of the Pt layer 2a and the Co layer 2b in the first Pt / Co multilayer film 2 are set to 15 ° and 5 °, respectively, and the Pt layer in the second Pt / Co multilayer film 3 is set. The thicknesses of 3a and Co layer 3b are set to 6 ° and 5 °, respectively. The total number of the Pt layer 2a and the Co layer 2b in the first Pt / Co multilayer film 2 is 20 to 40.
And the total number of Pt layers 3a and Co layers 3b in the second Pt / Co multilayer film 3 is also set to 20 to 40.

In the above configuration, a large Kerr rotation angle can be obtained by making light incident from the side of the second Pt / Co multilayer film 3 having a large Kerr effect. Also, the second Pt / Co multilayer film 2 having a large perpendicular magnetic anisotropy is formed on the first Pt / Co multilayer film 2.
Since the Co multilayer film 3 is arranged, the magnetization of the second Pt / Co multilayer film 3 is oriented in the direction of the axis of easy magnetization of the first Pt / Co multilayer film 2, that is, with respect to the first Pt / Co multilayer film 2. It is more stable to face vertically. Therefore, the second Pt
The perpendicular magnetic anisotropy of the / Co multilayer film 3 increases. Thus, a magneto-optical storage element having a large perpendicular magnetic anisotropy and a large Kerr rotation angle with respect to light having a short wavelength can be obtained.

The gist of the present invention is that the film thickness ratio between the Pt layer and the Co layer on the light incident side is smaller than the film thickness ratio between the Pt layer and the Co layer on the side opposite to the light incident side. Therefore, when light is incident from the substrate 1 side, the second
Is formed, and a first Pt / Co multilayer film 3 is formed thereon.
The Co multilayer film 2 may be formed. However, if the perpendicular magnetic anisotropy is first secured by arranging the first Pt / Co multilayer film 2 having a large film thickness ratio on the substrate 1 side, an even more ideal magneto-optical storage element can be obtained. can get.

A second embodiment of the present invention will be described below with reference to FIG. For convenience of explanation, members having the same functions as those shown in the drawings of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 2, the magneto-optical storage element of this embodiment has a substrate 1 and a Pt / Co layer formed on the substrate 1.
It is mainly composed of the multilayer film 4.

The Pt / Co multilayer film 4 is composed of a Pt layer 4a and Co
The layer 4b is alternately and repeatedly laminated.

The difference from the first embodiment is that only one Pt / Co multilayer film 4 is formed on the substrate 1,
In the t / Co multilayer film 4, the adjacent Pt layer 4a and Co
The film thickness ratio of the layer 4b, that is, (film thickness of Pt layer 4a / Co
The thickness of the layer 4b is not constant, but is set so as to gradually decrease as the distance from the substrate 1 increases. As a result, the side closer to the substrate 1 has a larger perpendicular magnetic anisotropy than the side farther from the substrate 1, and the side farther from the substrate 1 exhibits a larger Kerr effect than the side closer to the substrate 1. The Pt / Co multilayer film 4 is formed.

Specifically, for example, in the Pt / Co multilayer film 4, the thickness of the Pt layer 4 a closest to the substrate 1 is set to 15 °, and the Pt layer 4 a becomes farther from the substrate 1.
Of the Pt layer 4 farthest from the substrate 1
The thickness of “a” is set to 6 °. On the other hand, the thickness of the Co layer 4b is constant and set to 5 °. The total number of the Pt layer 4a and the Co layer 4b in the Pt / Co multilayer film 4 is 2
It is set to 0-100.

In the above configuration, P having a large Kerr effect
By allowing light to enter from the t / Co multilayer film 4 side, a large Kerr rotation angle can be obtained. In addition, the Pt / Co multilayer film 4
Has a higher perpendicular magnetic anisotropy on the side closer to the substrate 1 than on the side farther from the substrate 1, so that the electron spin of the Co layer 4 b farther from the substrate 1 also Co
The direction of the electron spin of the layer 4b, that is, the direction perpendicular to the Pt / Co multilayer film 4 is more stable. Therefore, the perpendicular magnetic anisotropy increases on the side far from the substrate 1. This has a large perpendicular magnetic anisotropy,
In addition, a magneto-optical storage element having a large Kerr rotation angle can be obtained.

A third embodiment of the present invention will be described below with reference to FIG. For convenience of explanation, members having the same functions as those shown in the drawings of the above-described embodiment are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 3, the magneto-optical storage element of this embodiment includes a substrate 1 and a first Pt formed on the substrate 1.
/ Co multilayer film 2, a second Pt / Co multilayer film 3 formed on the first Pt / Co multilayer film 2, and a second Pt / Co multilayer film.
A third Pt / Co multilayer film 5 formed on the multilayer film 3,
AlN or Si formed on the third Pt / Co multilayer film 5
And a transparent film 6 of N or the like.

The third Pt / Co multilayer film 5 includes a Pt layer 5a.
And a Co layer 5b are alternately and repeatedly laminated.

The difference from the first embodiment is that the second Pt
The third Pt / Co multilayer film 5 and the transparent film 6 as a protective film are formed on the / Co multilayer film 3.

The thickness ratio of the Pt layer 5a and the Co layer 5b in the third Pt / Co multilayer film 5, that is, (thickness of the Pt layer 5a / thickness of the Co layer 5b) is the second Pt / Co The thickness is set to be larger than the thickness ratio of the Pt layer 3a (see FIG. 1) and the Co layer 3b in the multilayer film 3, that is, (thickness of the Pt layer 3a / thickness of the Co layer 3b). Further, the total number of the Pt layers 5a and the Co layers 5b of the third Pt / Co multilayer film 5 is set to be smaller than the total number of the first and second Pt / Co multilayer films 2.3. ing.

Thus, the first and third Pt / Co
The second Pt / Co multilayer film 3 having a larger Kerr effect than the multilayer film 2 is different from the first and third Pt / Co multilayer films 2 having a larger perpendicular magnetic anisotropy than the second Pt / Co multilayer film 3.・ It will be sandwiched by 5.

Specifically, for example, first and third Pt
The thicknesses of the Pt layer 2a and the Co layer 2b in the / Co multilayer films 2 and 5 are set to 15 ° and 5 °, respectively, and the second Pt /
The thicknesses of the Pt layer 3a and the Co layer 3b in the Co multilayer film 3 are set to 6 ° and 5 °, respectively. Also, the first Pt /
The total number of the Pt layer 2a and the Co layer 2b in the Co multilayer film 2 is set to 20 to 40, and the second Pt / Co multilayer film 3
, The total number of layers of the Pt layer 3a and the Co layer 3b is also 20 to 4
0, and Pt in the third Pt / Co multilayer film 5
The total number of layers 5a and Co layer 5b is set to 4 to 18.

In the above configuration, a large Kerr rotation angle can be obtained by making light incident from the transparent film 6. That is, the light transmitted through the transparent film 6 becomes relatively thin third P
The second P which passes through the t / Co multilayer film 5 and has a large Kerr effect
Since the light is incident on the t / Co multilayer film 3, a large Kerr rotation angle is obtained. Further, since the second Pt / Co multilayer film 3 is sandwiched between the first and third Pt / Co multilayer films 2 and 5 having large perpendicular magnetic anisotropy, the second Pt / Co multilayer film 3 The magnetization is more stable in the direction of the axis of easy magnetization of the first and third Pt / Co multilayer films 2 and 5. Therefore, the second
The perpendicular magnetic anisotropy of the Pt / Co multilayer film 3 increases.
Thereby, a magneto-optical storage element having a large perpendicular magnetic anisotropy and a large Kerr rotation angle can be obtained.

[0027]

As described above, the magneto-optical storage element of the present invention is capable of forming the Co-layer with the adjacent Pt layer formed on the side close to the substrate.
The thickness ratio of the layer is adjusted to the adjacent Pt formed on the side remote from the substrate.
The thickness is set to be larger or equal to the film thickness ratio of the layer and the Co layer, so that the side closer to the substrate has a larger perpendicular magnetic anisotropy than the side farther from the substrate, On the side farther from the substrate, a Pt / Co multilayer film showing a larger Kerr effect than on the side closer to the substrate is formed. Therefore, a large Kerr rotation angle can be obtained by irradiating light from the Pt / Co multilayer film side having a large Kerr effect. Also, Pt
Since the / Co multilayer film has a higher perpendicular magnetic anisotropy on the side closer to the substrate than on the side farther from the substrate, the magnetization is perpendicular to the Pt / Co multilayer film even on the side farther from the substrate. Direction is more stable. Therefore, the perpendicular magnetic anisotropy increases even on the side far from the substrate. Thereby, there is an effect that a magneto-optical storage element having a large perpendicular magnetic anisotropy and a large Kerr rotation angle with respect to light having a short wavelength can be obtained.

The gist of the present invention is that the film thickness ratio of the Pt layer and the Co layer on the light incident side is smaller than the film thickness ratio of the Pt layer and the Co layer on the side opposite to the light incident side. Therefore, it is not always necessary to arrange a Pt / Co multilayer film having a large thickness ratio on the substrate side. However, Pt having a large film thickness ratio on the substrate side
If the perpendicular magnetic anisotropy is first secured by arranging the / Co multilayer film, an even more ideal magneto-optical storage element can be obtained.

[Brief description of the drawings]

FIG. 1, showing a first embodiment of the present invention, is a schematic configuration diagram of a magneto-optical storage element.

FIG. 2, showing a second embodiment of the present invention, is a schematic configuration diagram of a magneto-optical storage element.

FIG. 3, showing a third embodiment of the present invention, is a schematic configuration diagram of a magneto-optical storage element.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 first Pt / Co multilayer film 2a Pt layer 2b Co layer 3 second Pt / Co multilayer film 3a Pt layer 3b Co layer 4 Pt / Co multilayer film 4a Pt layer 4b Co layer 5 third Pt / Co multilayer film 5a Pt layer 5b Co layer

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Yoshiteru Murakami 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside Sharp Corporation (56) References JP-A-3-228238 (JP, A)

Claims (1)

(57) [Claims] In a magneto-optical memory device having a Pt / Co multilayer film in which a Pt layer and a Co layer are alternately and repeatedly laminated on a substrate, a film of an adjacent Pt layer and a Co layer formed on a side close to the substrate. A magneto-optical storage element, wherein the thickness ratio is set to be larger than the thickness ratio of an adjacent Pt layer and a Co layer formed on a side far from the substrate.