JPH04132030A - Magneto-optical recording film - Google Patents

Abstract

PURPOSE:To plan higher perpendicular magnetic anisotropy energy, lower saturation magnetization and larger coercive force by adding other elements into the iron family elements of alternately laminated films of noble metal elements and the iron family elements. CONSTITUTION:The multilayered films alternately laminated with the noble metal elements 3 and the iron family elements 2 are formed by alternately laminating at least one kind of the elements selected from Pt, Pd, Rh, and Au and at least one kind of the elements selected from Pt, Pd, Rh, Au, Nb, Ti, Ta, and Cr. The arbitrary control of magnetic characteristics, such as coercive force, Curie temp. and perpendicular magnetic anisotropy energy, is executed by arbitrarily selecting the concn. of the elements added to the Fe and Co at this time. The desired disk characteristics are obtd. in this way.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to magneto-optical recording that performs recording, reproduction, and erasing using laser light, and is particularly applicable to magneto-optical recording that has particularly high reliability and is capable of ultra-high density recording. Concerning recording materials.

[Conventional technology]

With the recent development of an advanced information society, the need for high-density and large-capacity file memory is increasing, and optical memory is attracting attention as a solution to meet this demand. Following read-only and write-once types, many companies have put magneto-optical recording devices into practical use as rewritable optical disks in recent years. Research and development is currently underway at many research institutions with the aim of improving its performance. One of these is the further improvement of recording density, and forming minute recording magnetic domains using short wavelength light is seen as a promising method. In that case, the problem is PbFe, which is currently widely used.
The problem with Co-based magneto-optical materials is that as the wavelength of the light used becomes shorter, the magneto-optic effect exhibited by the recording film becomes smaller and stable reproduction may not be possible. EP 0304873A 1 can be cited as a known example that solved this problem. This is used as a magneto-optical recording film.
This is an example using a film having a multilayer structure in which Co and Co are alternately laminated.

[Problem to be solved by the invention]

In the above conventional technology, the coercive force is not necessarily large enough to be used for magneto-optical recording, and the perpendicular magnetic anisotropy is also small, resulting in lack of stability as a perpendicularly magnetized film. A problem has arisen in that when information is recorded, it is not possible to ensure sufficient reliability in its storage.

An object of the present invention is to realize ultra-high-density magneto-optical recording by providing a magneto-optical recording material that has excellent magnetic properties such as coercive force and perpendicular magnetic anisotropy energy required for magneto-optical recording. It is in. That is, it is possible to provide a magneto-optical recording medium in which a minute recording area can be formed.

[Means to solve the problem]

A method using short wavelength light is seen as a promising method for improving recording density by forming minute recording magnetic domains. However, the current product TbFeC.

In such materials, as the wavelength of the light used becomes shorter, the Kerr rotation angle decreases, and stable reproduction may become difficult.

On the other hand, noble metal elements such as pt and Pd and Fe, C
It is known that a multilayer film in which iron group elements such as iron and iron are alternately laminated is useful for high-density recording using short wavelength light.

However, this film has a coercive force.

Magnetic properties such as the magnitude of perpendicular magnetic anisotropy were not necessarily suitable for magneto-optical recording.

In order to solve this problem, in an alternate laminated film of pt and CO, Pt, Pd, Rh, and Au are added to Co.

An alloy containing at least one element selected from Nb, Ti, Ta, Cr, etc., and Pt, Pd.

By using a multilayer film in which at least one element selected from Rh and Au is alternately laminated, coercive force and perpendicular magnetic anisotropy can be increased, making it suitable for ultra-high density magneto-optical recording. I was able to obtain the materials. And further T
By manufacturing an alloy made of rare earth-iron group elements represented by b -Fe -Co so as to be magnetically coupled with the above multilayer film, magnetic properties and magneto-optical properties as a magneto-optical recording film can be further improved. I was able to improve/improve. That is, it was possible to increase the coercive force and perpendicular magnetic anisotropy of the magneto-optical recording film as a whole. this is.

This is because saturation magnetization can be controlled by adding elements.

Furthermore, since the Curie temperature can also be controlled by adding elements to Co, the recording sensitivity can be arbitrarily selected. From the above, by using the present invention, 1. it became possible to increase the coercive force and perpendicular magnetic anisotropy, and also to control the Curie temperature, making it possible to easily obtain a disk having desired characteristics.

[Effect]

At least one selected from Pt, Pd, Rh, and Au
seed elements, Pt, Pd, Rh, and Au.

At least one selected from Nb, Ti, Ta, and Cr
By alternately stacking Fe or CO alloys containing seed elements, magnetic properties such as coercive force, Curie temperature, and perpendicular magnetic anisotropy energy can be adjusted arbitrarily by selecting the element concentration added to Fe or CO. can be controlled. As a result, desired disc characteristics were obtained. This is because by adding elements to Fe or Co, the magnetic properties of these iron group elements can be controlled.

〔Example〕

The details of the present invention will be explained below using Examples 1 and 2.

[Example 1] FIG. 1 is a schematic diagram showing the cross-sectional structure of the magneto-optical recording film produced in this example. The manufacturing procedure is as described below.

On a plastic or glass substrate 1, a transition metal element layer 2 of Co, 5Nb, and a noble metal element layer 3 are formed.
PT was selected as the material, and both were alternately laminated to produce a multilayer recording film by sputtering. A composite target in which Nb chips are uniformly arranged on a Co disk and p
A two-dimensional simultaneous sputtering method using a t-circular disk was used. The conditions at that time were to use a discharge gas and the pressure was 5 x 10-'To
rr, input RF main power CoNb is 4.2W/cJ, Pt
is 6.6 W/, ffl, and the substrate rotation speed is 12 Orpm. The thickness of each layer of the recording film produced in this way was Co
The Nb layer has 5 layers, the PT layer has 12 layers, and the total thickness of the multilayer film is 150 layers.

The perpendicular magnetic anisotropy energy of the magneto-optical recording film thus prepared was 7 x 10 serg/d,
It can be seen that the Co/P layer, which does not contain Nb, is greatly increased compared to the 9×10' erg/al of the alternately laminated multilayer film, and can exist stably as a perpendicular magnetization film.

Further, it can be seen that the saturation magnetization Ms is 170 emu/cc, which is significantly smaller than 700 emu/cc of the film not containing Nb. Furthermore, the coercive force Hc was 6KOe, which was significantly increased compared to IKOe without Nb.

This allowed the recorded information to be stored stably.

Further, the temperature dependence of the Kerr rotation angle is shown in FIG.

(P t / Co 1oo-xN b x)n Nb concentration:
As the Curie temperature increases with t%,
The temperature decreased to 380°C, 305°C, and 205°C. By controlling the Nb concentration in this manner, the Curie temperature can be arbitrarily selected. However, when 20 at % or more of Nb was added, the magnetism was conversely lost and the perpendicular magnetic anisotropy disappeared. This effect is not limited to Nb, but also Pt and Pct.

The same holds true when Rh, Au, Ti, Cr, Ta, W, and Mo are added. However, when W and Mo were added at 1 oat%, the magnetism disappeared. When other elements were added, the behavior on magnetism was the same, and the magnetic properties disappeared when about 20% was added. Here, Pt, Pd.

When Rh and Au were added, the reflectance increased and the figure of merit (J, θk) of the disk increased, so a stable reproduction signal was obtained. Since magnetic properties can be easily controlled by adding elements in this way, desired disk properties can be easily obtained.

[Example 2] FIG. 3 is a schematic diagram showing the cross-sectional structure of the magneto-optical recording film produced in this example.

On a plastic or glass substrate 1, pt was added as a noble metal element 3 under the same sputtering conditions as in Example 1.
As the transition metal element layer 2, a multilayer film in which CogoTi□0 was alternately laminated was formed. The thickness of the PT layer is 10, CoT.
The number of people in the i-layer was 5, and the total thickness of this alternately laminated multilayer film layer was 130 people.

A rare earth-iron group element layer 4 of Tb2. Fe, □CO□. Nb.

The layer was formed to a thickness of 870 layers. Film formation was performed using a sputtering method, and the conditions were that the target was TbFeCo.
Nb alloy was used, Ar was used as the discharge gas, the discharge gas pressure was 5 x 10-'Torr, and the input RF power density was 4.2.
It is W/cd.

The perpendicular magnetic anisotropy of the recording film thus prepared is Tb
It is dominated by the FeCoNb film and has a 1x10'erg/
The CD was noticeably large. Further, the temperature dependence of the Kerr rotation angle of this film is shown in FIG. For comparison, Ti-free (pt/Co)n and T b Fe Co N b
Those of the alternately bonded membrane are also shown. according to it,(
In Pt/CoTi)n/TbFeCoNb film, the Curie temperature is approximately 200°C, whereas in (Pt/Co)l
that of the l/TbFeCoNb film is 340°C, and that of the Ti
By adding , the Curie temperature could be controlled. In addition to Ti, this effect also applies to Pt, Pd, Rh, Au, Nb, and Ta.
, Cr, or more than one type of element may be used. In addition to CO, Fe may be used, C or FeCo alloy may be used, and Pd, Pd, and Pt may be used instead of PT.
Similar effects can be obtained by using Rh, Au, or an alloy thereof. Further, the same effect can be obtained even if Ha, Dy, or Gd is used in addition to Tb in the rare earth-iron alloy layer. Moreover, this rare earth-iron group alloy layer and a (Pt/CoX) alternately laminated multilayer film (X=Nb).

Ti, Ta, Cr, Pt, Pd, Rh, A
The magnetic properties can be arbitrarily controlled by appropriately controlling the magnetic properties with u).

〔Effect of the invention〕

According to the present invention, when other elements are added to the iron group element in an alternately laminated film of noble metal elements and iron group elements, the perpendicular magnetic anisotropy energy is increased, the saturation magnetization is decreased, and the coercive force is increased. This is effective in improving the reliability of recorded data retention. Also, by appropriately selecting the concentration of added elements.

Curie temperature and temperature characteristics of magnetic properties can be controlled, and various performances such as recording sensitivity of the disk can be arbitrarily selected.

As a result, maximum performance can be obtained from the disk and drive system.

[Brief explanation of drawings]

1 and 3 are schematic cross-sectional views of magneto-optical recording films according to embodiments of the present invention, and FIGS. 2 and 4 show temperature dependence of the Kerr rotation angle of magneto-optical recording films according to embodiments of the present invention. FIG. DESCRIPTION OF SYMBOLS 1...Substrate, 2...Transition metal element layer, 3...Vaporized metal element layer; A (C) 4GaniT ('C)

Claims (1)

[Claims] 1. In magneto-optical recording in which recording, reproduction, or erasing is performed using laser light or a magnetic field or both, the recording film is at least one selected from Pt, Pd, Rh, or Au. A layer consisting of one type of element, and a layer mainly composed of at least one type of element selected from Fe and Co, and at least one type selected from Pt, Pd, Rh, Au, Nb, Ti, Ta, and Cr. 1. A magneto-optical recording film characterized in that it is a multilayer film in which layers made of an alloy containing the elements are alternately laminated. 2. A magneto-optical recording film characterized in that an alloy layer made of a rare earth element and an iron group element or a layer made of an alternately laminated film is provided so as to be magnetically coupled to the multilayer film according to claim 1. . 3. Tb as the rare earth element described in claim 2
, Dy, Ho, or Gd, and at least one element selected from Fe and Co as an iron group element. 4. At least one element selected from Fe and Co described in claim 1, including pt, Pd, Rh, and A.
an alloy layer containing at least one element selected from u, Nb, Ti, Ta, and Cr; and Pt, Pd, Rh, and Au.
A multilayer film in which at least one type of layer selected from
In the multilayer film provided to magnetically couple the layers of item 1 and item 3, the magnetic properties of the recording film are controlled by controlling the concentration of elements added to Fe and Co. magneto-optical recording film.