JP2602425B2 - Amorphous magneto-optical layer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magneto-optical layer of a magneto-optical recording medium used for a hard disk, a floppy disk, a document file, and the like, and in particular, an amorphous magneto-optical layer excellent in a magneto-optical effect. Pertains to layers.

2. Description of the Related Art In recent years, various studies have been made on magneto-optical recording media for performing magnetic recording using semiconductor laser light for high-density recording. In particular, in order to be used for high-density recording, the magnetic film needs to have an easy axis of magnetization in a direction perpendicular to the film surface. Conventionally, magnetic films used in these magneto-optical recording media include Gd-Co, Gd-Fe, Tb-Fe, Gd-Tb-Fe, Tb-Dy-Fe
However, magneto-optical recording media using these amorphous alloy magnetic materials have high recording sensitivity and high speed (frequency, several MHz) by semiconductor laser light.
_Although there is an advantage that recording can be performed in ( _Z ), there is a problem that the magneto-optical effect is not sufficiently satisfactory. Therefore, Gd-Tb-Fe-Co4
Japanese Patent Application Laid-Open No. Sho 58-196639 discloses that the Kerr rotation angle is increased by using the original amorphous magnetic film to improve the magneto-optical effect.
No. 1993. In order to make a magneto-optical recording medium using such an amorphous alloy magnetic material, a magnetic film is generally formed by depositing the magnetic material on a substrate such as a glass plate by a method such as vacuum evaporation or sputtering. I have. Recording and reproduction on the magneto-optical recording medium thus obtained are performed as follows. In other words, the recording is performed by irradiating the magnetic film with a laser beam modulated by an information signal by utilizing the rapid change characteristic of the coercive force corresponding to the temperature change near the Curie temperature or the compensation temperature of the magnetic film and heating the magnetic film surface. Is performed by reversing the direction of. Also, the reading is performed by reading the Kerr rotation angle of the magnetic film which has been reversely recorded in the reproducing manner. As described above, the recording and reproduction of the information signal in the case where the light is hardly transmitted like the amorphous alloy magnetic material utilizes the Kerr effect. The Kerr effect is a rotation phenomenon of a plane of polarization when light is reflected on the surface of a magnetic material, and a) a polar effect,
There are b) a longitudinal (longitudinal) effect and c) a transverse (transverse) effect. In particular, in the case of an amorphous alloy magnetic material, the pole effect of a is used, and reproduction is performed using the Kerr rotation angle θK. . Therefore, if the Kerr rotation angle θK is slightly increased, the magneto-optical effect is increased and the reproduction characteristics are improved.

However, the Kerr rotation angle θK of the aforementioned quaternary amorphous magnetic material composed of Gd-Tb-Fe-Co is as small as about 0.4 deg, and it is difficult to say that the optical reproduction characteristics are sufficiently satisfied.

An object of the present invention is to provide an amorphous magneto-optical layer in which the Kerr rotation angle θK in an amorphous alloy magnetic material having an easy axis of magnetization in a direction perpendicular to the film surface is further increased, thereby improving the light reproduction characteristics. To provide.

Configuration present invention has an axis of easy magnetization in a direction perpendicular to the film plane _{{(Gd x Tb 1-x} ) y (Fe 1-z Co z) 1-y} 1-a Sn a or {(Gd _x Tb _{1 -x} ) _y (Fe _1-z Co _z ) _1-y ｝ _1-b Cn _b (where 0 <x <1, 0.1 ≦ y ≦ 0.4, 0 <z ≦ 0.5,
0.001 ≦ a <0.04, 0.001 ≦ b <0.02).

The amorphous magneto-optical layer of the present invention is formed on an appropriate support to a thickness of about 0.01 to 1 μm by a method such as vacuum deposition, sputtering, or ion plating.

When a magnetic thin film is formed by sputtering, each magnetic component is used individually or in combination as a target, and the composition of the magnetic material is controlled by the area ratio of the target surface.

As the support, glass, plastic, ceramic, and the like can be used. A protective layer, a heat insulating layer, a reflective layer, and the like are optionally provided between the amorphous magneto-optical layer of the present invention and the support or on the upper surface.

Effect thus obtained _{{(Gd x Tb 1-x} ) y (Fe 1-z Co z) 1-y} 1-a Sn a or _{{(Gd x Tb 1-x} ) y (Fe 1-z Co _z ) _1-y ｝ _1-b Cn _b (where 0 <x <1, 0.1 ≦ y ≦ 0.4, 0 <z ≦ 0.5,
0.001 ≦ a <0.04, 0.001 ≦ b <0.02) When the amorphous magneto-optical layer made of a film is irradiated with a laser beam modulated by an information signal and heated, the Kerr rotation angle θK of the amorphous magneto-optical layer is Therefore, the magneto-optical recording medium capable of high-density recording / reproduction is improved in light reproduction characteristics when reproducing it by the Kerr effect, improving the S / N ratio and increasing the number of recording pits. Will be obtained.

 Examples will be described below.

Example of application Approx.
An amorphous magneto-optical layer made of Gd-Tb-Fe-Co-M with a thickness of 1500 to 2000 mm was formed. The target was formed using a composite method by placing an alloy chip of Gd _0.5 Tb _0.5 and an M chip on a Fe _0.9 Co _0.1 alloy disk, and forming a thin film while controlling each composition ratio by the area ratio of the target surface.

The conditions for forming (sputtering) each amorphous magneto-optical layer are shown in the following table.

Each amorphous magneto-optical layer has a (Fe _0.9 Co _0.1 ) _0.78 (Gd _0.5 Tb _0.5 ) _0.22 or (Fe
_0.9 Co _0.1 ) _0.79 (Gd _0.5 Tb _0.5 ) _0.21 composition (Gd
_0.5 Tb _0.5 ) is replaced by M, that is, (Fe _0.9 Co _0.1 ) _0.78 ｛(Gd _0.5 Tb _0.5 ) _1-x Mx｝ _0.22 or (Fe _0.9 Co _0.1 ) _0.79 ｛(Gd _0.5 Tb _0.5 ) _1-X Mx｝ _0.21
When M was Cu, the former composition was used, and when M was Sn, the latter composition was used.

He-Ne laser (λ = 633nm) from the substrate side
And the Kerr rotation angle θK and the coercive force Hc were determined using the Kerr effect.

The results are shown in FIG. 1 and FIG. From these figures, it can be seen that increasing the amount of X, ie, M, decreases Hc but increases θK. In this embodiment, a part of (Gd _0.5 Tb _0.5 ) is replaced by M. Therefore, when the amount of M is increased, the amount of Tb contributing to the anisotropy decreases, and Hc
Has not been able to increase the amount of M so much because
If the ratio of (Fe _0.9 Co _0.1 ) and (Gd _0.5 Tb _0.5 ) is kept constant and the amount of M is increased, the decrease in Hc can be suppressed and the amount of M can be increased.

Here, Gd-Tb-Fe in the case where the Kerr rotation angle θK is the largest in the amorphous magneto-optical layer in each of the embodiments is again described.
-Co-M film composition, Kerr rotation angle θK, and the increase in θK compared to the case where M is not contained are shown.

[Brief description of the drawings]

FIGS. 1 and 2 are diagrams showing changes in θK and Hc when the amount of M in each amorphous magneto-optical layer in this embodiment is changed.

Claims (1)

(57) [Claims] (1) {(Gd _x Tb _1-x ) _y (Fe _1-z Co _z ) _1-y ｝ _1-a Sn
_a or ｛(Gd _x Tb _1-x ) _y (Fe _{1 -z} Co _z ) _1-y ｝ _1-b Cn _b (where 0 <x <1, 0.1 ≦ y ≦ 0.4, 0 <z ≦ 0.5,
An amorphous magneto-optical layer having an easy axis of magnetization in a direction perpendicular to the film surface represented by a composition formula of 0.001 ≦ a <0.04, 0.001 ≦ b <0.02).