JPS6098611A - Manufacture of thermomagnetic recording material - Google Patents

Abstract

PURPOSE:To obtain an alloy film having a low Curie temperature and large magnetic force-rotation angle by using Dy, Tb, Fe or Dy, Tb, Fe, Co as metallic- gas supply sources, making a substrate temperature lower than an alloy-film crystallization temperature and depositing metallic gases. CONSTITUTION:An amorphous alloy film is formed by depositing a metal gasified through a metallic-gas depositing method, such as a vacuum evaporation method, a sputtering method, an ion plating method, etc. on a substrate. Three elements of Dy, Tb and Fe or four elements of Dy, Tb, Fe and Co are used as metallic-gas supply sources, and employed at atomicity ratios in formula. When each gasified metallic gas is attached on the substrate, the temperature of the substrate is kept at a value lower than the crystallization temperature of the alloy film. Accordingly, the amorphous alloy film having a low Curie temperature, large magnetic force-rotation angle and an axis of easy magnetization in the vertical direction is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for producing a thermomagnetic recording material comprising an amorphous rare earth-transition metal alloy film. Specifically, the thermomagnetic recording material is an amorphous alloy film having an axis of easy magnetization perpendicular to the film surface, and the magnetic recording pattern is transferred by utilizing the temperature dependence of the coercive force of the material. The present invention relates to a method of manufacturing a material mainly suitable for thermomagnetic transfer recording in which a transferred pattern is read out using a magneto-optical effect such as the Kerr effect.

(Background of the Invention) Magnetic transfer refers to magnetizing another magnetic recording medium using a stray magnetic field generated from a magnetic pattern on a recording medium such as a magnetic tape or magnetic disk, and various methods are known for this purpose. It is being

Among these, there is a method in which an amorphous rare earth-transition metal alloy film having a vertical 1μ magnetic anisotropy is used as a magnetic transfer material and the magnetic Kerr effect is used as a method for reading out the magnetization pattern transferred to the film (e.g. No. 50203), the material has a high light reflectance and the most efficient effect can be used for optical readout, so a transferred image with good contrast can be observed. Furthermore, since the transferred pattern can be observed from directly above, it has the advantage that there is no image distortion, and is used as an excellent transfer technique.

Transfer methods using an amorphous rare metal-transition metal alloy film having perpendicular magnetic anisotropy can be further classified into non-bias transfer and bias transfer.

Non-bias transfer is a method in which the transfer material is magnetized only by the stray magnetic field generated by the transferred recording medium during transfer, and since magnetization must be performed by a weak stray magnetic field, the magnetic properties of the transfer material used are must have a sufficiently small coercive force at room temperature. Therefore, non-bias transfer is advantageous in that magnetic transfer can be easily performed without requiring any equipment other than the transferred recording medium and the transfer recording compatibility during transfer, but the coercive force of the transfer material 1 is small. Therefore, when a weak magnetic field is applied from the outside, the transferred pattern easily disappears, which poses a problem in the preservation of the transferred pattern.

On the other hand, bias transfer is a method in which magnetic transfer is performed while applying a magnetic field or heat to a transfer material during transfer. Method t-J1 of applying a magnetic field is a method in which a DC or AC magnetic field is externally applied during transfer to reduce the apparent coercive force of the transfer material to promote transfer. The method of applying heat is called thermomagnetic transfer, and utilizes the fact that the coercive force of the transfer material decreases with increasing temperature. That is, when a frozen transfer material in which the transfer material is brought into close contact with a transfer material such as a magnetic tape is heated, the coercive force of the transfer material decreases, and the transfer material is sufficiently magnetized by the weak floating magnetic field of the transfer material t1. The transfer pattern is then frozen into the transfer material as the temperature of the transfer material decreases and the coercive force increases. this is,
This corresponds to thermomagnetic recording in a weak magnetic field.

Therefore, as a thermomagnetic transfer material, low energy is required to prevent deterioration of the alloy film due to heating during transfer and to avoid increasing the size of the heating device! A material with a low profile and capable of thermomagnetic transfer is desired.In other words, a transfer material 1 with a low temperature is desired.

In addition, from the viewpoint of storage stability of the transferred pattern, it is desirable that the material has a large coercive force at room temperature, and from the viewpoint of contrast during readout, it is desirable that the material has a large magneto-optical effect such as the magnetic Kerr effect.

(Prior Art) Conventionally known amorphous rare-transition metal alloy films for thermomagnetic transfer include a TbFe film and an I)yFe film. Although these have a large coercive force at room temperature and are satisfactory in terms of preservation of transferred patterns, TbFe has a Curie temperature of 120°C and a magnetic Kerr rotation angle of 0. 1 7°
On the other hand, in D: i'F e, the key temperature is 60
°C, the magnetic Kerr rotation angle is 0.08°. In other words, DyFe, which has a low Curie temperature and excellent transfer characteristics, has a small magnetic Kerr rotation angle and low contrast during readout, so it has the disadvantage that the readout transferred image is unclear. On the other hand, although TbFe has a relatively large magnetic Kerr rotation angle, it has a drawback in that the key temperature is high and there is a risk of deterioration. Under such circumstances, it is hoped that a thermomagnetic recording material with a low Curie temperature and as large a magnetic Kerr rotation angle as possible will emerge.

(Objective of the Invention) The present invention has been made in view of the above circumstances, and provides an amorphous rare earth-transition metal alloy film suitable for use in thermomagnetic transfer that has a large magnetic Kerr rotation angle and a sharp key. This was developed to provide a method for manufacturing materials with a low temperature.

As a result of research on the combination of metal elements used as raw materials, their atomic ratio, and the method for forming an alloy film, the present inventor found that
This has led to the present invention.

(Structure of the Invention) The present invention uses a metal gas agglomeration method when producing a thermomagnetic recording material comprising an amorphous rare earth-transition metal alloy film having an axis of easy magnetization perpendicular to the film surface. The metal gas supply source is Dy, Tb, Fe or Dy,
Tb, Fe, and Co, and each element is represented by the general formula % formula %) which indicates the atomic ratio to be gasified, and in this general formula, X is 025≦X≦08°, y is 0≦y≦ 05°Z is a numerical value in the range of 0.1≦Z≦05, and the temperature of the substrate on which the metal gas consisting of each of the above elements aggregates to form an alloy film is lower than the crystallization temperature of the alloy film. The present invention relates to a method of manufacturing a thermomagnetic recording material, characterized in that an amorphous alloy film is formed on the substrate.

The metal gas aggregation method used in the present invention is a method of agglomerating gasified metal on a substrate, and includes vacuum evaporation method,
There are sputtering methods, ion blating methods, etc. In the vacuum evaporation method, ]-X 10-'Torr or less, usually 10
= Heating the evaporation source with resistance heating or electric beam under a vacuum of around Torr, increasing the vapor pressure of the atoms or molecules that make up the evaporation source, and condensing the vapor evaporated from the evaporation source onto the substrate. 1. Sputtering is a method of forming a thin film using an inert gas such as argon at 1 x 10-2~
Two electrodes are placed in a low-pressure atmosphere of about 1 x 1 O-3 Torr, a voltage of several hundred to several hundred V is applied to the upper part of the gas, and the gas is ionized. ), and the atoms are ejected from the surface.The ejected atoms are in a gasified state, reach the substrate with high energy, and condense.

Therefore, in the case of the vacuum evaporation method using a metal gas supply source in the present invention, it is an evaporation source, and in the spuck method, it is a target. In the present invention, three elements Dy, Tb and Fe or I) y, Tb,
Although the four elements Fe and CO are used, it is not excluded that other rare earth elements or other transition elements may be added as long as the effects of the present invention are not impaired.

These metal gas supply sources may use each metal independently, or may be mixed or alloyed in advance. In any case, the atomic ratio of each element to be gasified, that is, the original J when released as a gaseous metal.
”-The general formula showing the number ratio is CDVr Tb(] −zl
]v'-COyFe(1-y), i(1,).

In the above formula, X is the atomic ratio of Dy to the sum of the original r-number ratios of Tb and Dy, and y is the atomic ratio of Co to the sum of the original f' number ratios of Fe and Co. , and Z is the atomic ratio of the rare earth element to the sum of the atomic ratios of the rare earth element and the transition metal element.

In the present invention, in order for a thermomagnetic recording material with a low Curie temperature and a magnetic Kerr rotation angle of 11 to be
It has been found through experiments that the numerical value of is important, and that excellent results can be obtained in the range of 025≦X≦08. X
When is within this range, the key temperature is lower and the magnetic Kerr rotation angle is also lower than that of TbFe, which is known to have a relatively large magnetic Kerr rotation angle but a high key temperature. It has a superior magnetic Kerr rotation angle and a larger magnetic Kerr rotation angle than I)yFe, which is conventionally known to have a low Curie temperature but a small magnetic Kerr rotation angle. , and a comparable temperature can be obtained. That is, by using Tb and Dy as a metal gas supply source in a specific blending ratio, a material can be obtained that has the advantages of both 'l'b l'i'e and DyFe while eliminating the drawbacks of both. It was discovered that it could be done. In order to obtain a lower key temperature and a larger magnetic wheel rotation angle, the desirable range of the value of X is 0.3≦X≦0.6, and the more desirable range is 035≦X≦05. be.

Further, the numerical value of y indicating the atomic ratio of CO to the sum of the atomic ratio of f'e and CO is 0≦y≦0.5.

That is, although a certain degree of effect can be obtained by using Fe alone as the transition metal in the metal gas supply source, the addition of CO tends to increase the magnetic Kerr rotation angle, and the amorphous alloy film formed oxidation resistance is improved. The value of y is desirably 0.05 or more from the viewpoint of magnetic Kerr rotation angle, and 0.1 or more from the viewpoint of oxidation resistance. On the other hand, if a metal gas supply source containing more COO than Fe is used, the magnetic Kerr rotation angle of the formed amorphous alloy film tends to decrease, so the value of y must be set to 0.5 or less. In order to use the most efficient effect for optical readout and to obtain an undistorted image when observed from the beam, it is necessary to use an amorphous material. The rare earth-transition metal alloy film must be formed so that the axis of easy magnetization is perpendicular to the film surface. For this purpose, the mixing ratio of rare earth elements and transition metal elements in the metal gas supply source becomes a problem, and the value of 2 in the above general formula has an important meaning. The optimal value of Z may vary slightly depending on the values of X and y as well as the gasification temperature of the metal gas supply source, but if the value of Z is less than 01 or greater than 0.5,
Since the direction of the axis of easy magnetization of the amorphous alloy film to be formed is not perpendicular to the film surface, the value of B is 01≦Z≦0.
It needs to be 5. Furthermore, in order to produce a thermomagnetic recording material that has a large coercive force, a good squareness ratio, and a high contrast transfer pattern image, and is also excellent in terms of application, the value of 2 is as follows.
It is more desirable that 0.15≦2≦0.45.

Note that if the value of Z changes within the above range, the characteristics of the Curie temperature and magnetic Kerr rotation angle of the amorphous alloy film to be formed will be slightly affected, but regardless of the value of 2, Dy and T
Characteristic effects can be obtained based on the combination of b. Also, regardless of the value of y set to any value within the above range, [)y and Tb
The changes in Kerr temperature and magnetic Kerr rotation angle with respect to changes in the blending ratio show similar trends.

In order to gasify the metal gas supply source with the above composition, when using a vacuum evaporation method, a resistance furnace, high frequency furnace, electron beam furnace, etc. is used, and I
A metal serving as a metal gas supply source (evaporation source) is heated in a vacuum of less than r, preferably less than LX 10 ''L:orr.

When an alloy or a mixture is used as an evaporation source, the heating temperature is the same for all components, but if the evaporation source is separated for each metal, it is possible to set different heating temperatures for each metal. In any case, it is necessary to heat the metals to a temperature higher than the temperature at which they evaporate, and Tb, Dy, Fe,
C.

(approximately 1,300 to 1,500°C), preferably 1,700°C or higher, more preferably 2,000°C or higher. However, when a tungsten boat or the like is used as a container for storing the evaporation source, the temperature is limited to about 3000°C. In addition, when the evaporation source is an alloy, it is desirable to use a flash evaporation method so as not to change the composition during evaporation.

Further, when using the sputtering method, any of the 7 bipolar, three-polar, four-polar, magnetron, high-frequency, bias, and non-transparent tV AC types can be used as the sputtering method.

Vapor deposition is superior in terms of fast film formation rate and no rise in substrate temperature, but sputtering has advantages such as good adhesion to the substrate and easy composition adjustment. It can be selected as appropriate whether to use it or not.

The metal gases of each element gasified from the metal gas supply source mentioned above are deposited on the substrate and aggregated in a mixed state to form an alloy film. In order to bring this alloy film into an amorphous state, it is necessary to maintain the temperature of the substrate lower than the crystallization temperature of the alloy film. Normally, the crystallization temperature of the furnace-transition metal alloy film is 3
Since the temperature is approximately 0.000C, the substrate is held at a much lower temperature. If the temperature of the substrate is likely to rise higher than this, it is necessary to cool the substrate from the back with water, but normally, for example, when heating to about 2000 degrees Celsius with vacuum evaporation method, the substrate is cooled. Even without this, the temperature can be kept well below 300°C.

The material used for the substrate is one that does not cause softening, deformation, degassing, etc. due to the rise in temperature of the substrate when metal gas adheres and coagulates. Examples include glass, plastics, metals, ceramics, etc. can be mentioned. Further, the substrate can be used in a card, tape, disk, or other form depending on the purpose of use.

Further, the thickness of the amorphous 91 alloy film formed based on the method of the present invention is preferably 100λ or more so that the axis of easy magnetization is stably oriented perpendicular to the film surface. In addition, when reading out only by the magnetic Kerr rotation angle for monthly thermomagnetic transfer, it is desirable to use a thickness that does not allow light to pass through, that is, about 1000 mm or more. It is known that the Faraday rotation angle is large, and when reading using Faraday rotation, when light passes through it, it is used together with Fe as a metal gas supply source, and by gasifying it at a specific mixing ratio.
It is possible to form an amorphous rare earth-transition metal alloy film that has the characteristics of both a low IJ temperature and a large magnetic Kerr rotation angle.

Therefore, when the thermomagnetic recording material produced by the method of the present invention is used for transfer, transfer 11! The required rise in the temperature in the vicinity of the Curie temperature is small, and there is little deterioration of the alloy film due to heating, and since it has a large magnetic Kerr rotation angle, it is possible to reduce the contrast when reading transferred information. Can be read well.

Furthermore, within the scope of the present invention, C as a metal gas source.
When o coexists, the oxidation resistance of the alloy film improves,
A film with better properties against deterioration can be obtained.

As described above, the method of the present invention provides a thermomagnetic material that is superior to conventionally used TbFe and The recording material can be put to practical use.

Although the thermomagnetic recording material produced according to the present invention has mainly been described for use in transfer, its characteristics
2. It is also possible to use it as magneto-optical recording 4'A11.

Example 1 and Comparative Examples 1) y,
TI), using an alloy consisting of Fe and co as an evaporation source by the method described below, the general formula % formula % of the atomic ratio of these elements to be gasified is as shown in Table 1, and the four elements are were simultaneously deposited on a substrate to form an amorphous alloy film, and five samples were created.

Table 1 For each sample, the surface of the substrate was sufficiently degreased, and a cleaned Schiff/slide glass was used at room temperature.

For the evaporation source, each element was weighed to have the atomic ratio shown in Table 1, alloyed using the Arcmel I method, and the resulting alloy was pulverized into fine particles, which was used as the evaporation source for Fluzy vacuum evaporation. .

The composition of the evaporation source was analyzed to be the same as the weighed value.

The temperature of the tungsten boat during vapor deposition was around 2500° C. according to the light temperature side. The deposition time was about 5 seconds.

The degree of vacuum during vapor deposition was 6×10 −0 Torr.

When the temperature of the glass substrate during vapor deposition was measured by touching the glass substrate with a thermocouple, it was found to be the same as room temperature, and no change was observed during vapor deposition.

The film thickness of the alloy film formed on the substrate was within the range of 1000 to 2000λ for each sample, as measured by optical interferometry.

The magnetic Kerr rotation angle and temperature of the amorphous alloy film prepared as described above were measured at a wavelength of λ-633 using the effect as much as possible.

For the five tests above, take the value of X on the horizontal axis, and change the magnetic car rotation angle and key temperature.
For q11, the changes in causticity shown in Figure 1 as X changes were investigated.

As is clear from Fig. 1, when X is a value in the range of 0.25≦I≦08, the key temperature is 102℃~
Low temperature of 55°C and magnetic Kerr rotation angle of 0.20° to 0.14°
°, which is sufficiently large. In the erection, X is 0
If the numerical value is in the range of 3≦X≦0.6, the key temperature will be in the lower range of 70°C to 55°C, and the magnetic car rotation angle will be in the lower range of 020° to 0.5°C. ]If the range is larger than 8°, and if X is a value in the range of 0.35≦X≦05, then the magnetic field temperature will be 60°C to 55°C, and the magnetic Kerr rotation angle will be 0.20” to 55°C. 0.19° range, conventional T))
It was superior to F e and D y F e! 11 items are obtained.

Example 2 The metals of the evaporation source are Dy, Tb, and FC of the 31Φ class, and in the general formula of the original J' number ratio to be gasified, the values of r, y, and z are x = 0.4. ．． y=0. z
= 0.22, but in the same manner as in Example J, each element was simultaneously deposited on the substrate to form an amorphous alloy film.

The temperature of the tungsten boat during furanoso vacuum deposition was approximately 2500°C.

When the characteristics of the prepared sample were measured in the same manner as in Example J, the Keeley ηu1 degree was 50°C and the magnetic Kerr rotation angle was 0.16°.

[Brief explanation of the drawing]

Figure 1 shows a general formula showing the atomic ratio of each element in the metal gas supply source to be gasified when producing a thermomagnetic recording material consisting of an amorphous rare earth-transition metal alloy film by the metal gas agglomeration method. Medium, D for maximal number 1 of Tb and Dy atomic ratio
2 is a graph showing changes in the Giley temperature and magnetic Kerr rotation angle of the material with respect to changes in the numerical value of X without showing the atomic ratio of y. Figure C1, χ, Myota and I Nao

Claims (5)

[Claims] (1) When manufacturing a thermomagnetic recording material consisting of an amorphous rare earth-transition metal alloy film having an axis of easy magnetization perpendicular to the film surface, it is manufactured using a metal gas aggregation method, and the metal gas The supply source is Dy, Tb, Fe or Dy, Tb,
The general formula showing the atomic ratio of each element to be gasified is CDYx Tb(+-Jt (COyFe(ly))
In this general formula, r is 0.25≦X≦0.8゜y is O≦y≦0.5゜2 is a numerical value in the range of 01≦2≦0.5. , maintaining the temperature of the substrate on which the metal gas consisting of each of the above elements condenses to form an alloy film at a temperature lower than the crystallization temperature of the alloy film to form an amorphous alloy film on the substrate. A method for producing a thermomagnetic recording material, characterized in that: (2) The method for producing a thermomagnetic recording material according to claim 1, wherein χ is a numerical value in the range of 0.3≦X≦0.6. (3) The method for producing a thermomagnetic recording material according to claim 1, wherein x is a numerical value in the range of 0.35≦ and r≦0.5. (4) The method for producing a thermomagnetic recording material according to claim 1, wherein y is a numerical value in the range of 0.05≦y≦0.5. (5) The method for producing a thermomagnetic recording material according to claim 1, wherein y is a numerical value in the range of 0.1≦y≦0.5.