JPH0343768B2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an amorphous soft magnetic thin film, and particularly to an amorphous soft magnetic thin film having a large saturation magnetic flux density Bs and a small saturation magnetostriction constant λs. This is what we are trying to do.

[Background technology and its problems]

In the field of magnetic recording, advances are being made to increase the density and frequency of recording signals, such as in the perpendicular magnetic recording system. Fe in powder,
Magnetic tapes with high residual magnetic flux density Br and high coercive force Hc, such as so-called metal tapes using powder of ferromagnetic metals such as Co and Ni, and vapor-deposited tapes in which ferromagnetic metal materials are deposited on a base film by vapor deposition. Recording media are being used more and more. For this reason, the head material of the magnetic head used for recording and reproduction of this type of magnetic recording medium is required to have a high saturation magnetic flux density Bs and a high magnetic permeability, that is, a small saturation magnetostriction constant λs.

On the other hand, along with the above-mentioned high-density recording, the track width of the recording track recorded on the magnetic recording medium is also becoming narrower, and in response to this, the track width of the magnetic head is also required to be extremely narrow. ing.

Conventionally, for example, a so-called composite magnetic head has been developed in which a soft magnetic thin film serving as a magnetic core and an insulating layer are alternately deposited on a non-magnetic substrate such as ceramics, and this is used as a track part, and a soft magnetic thin film and a conductive thin film are insulated. A thin film magnetic head having a multi-layered structure using body thin films has been proposed, and amorphous soft magnetic thin films are attracting attention as soft magnetic thin films used in these types of magnetic heads.

This amorphous soft magnetic thin film has many excellent properties such as close to zero magnetostriction, high magnetic permeability, and no magnetocrystalline anisotropy, making it extremely useful as a soft magnetic thin film for the above-mentioned magnetic head. It is known that there is.

By the way, the material of the above-mentioned amorphous soft magnetic thin film is generally a transition metal element such as Fe, Ni, Co, etc., Si,
Metal-metallic amorphous alloys containing metalloid elements such as B and P are known, but it is difficult to secure a predetermined saturation magnetic flux density Bs with these metal-metallic amorphous alloys. However, when used in a single magnetic pole head for perpendicular recording, for example, the saturation magnetic flux density Bs becomes insufficient. In other words, in order to reduce the thickness of the main magnetic pole to 3000 Å or less in the single magnetic pole head for perpendicular recording, the soft magnetic thin film constituting the main magnetic pole must have a saturation magnetic flux density Bs of 14000 Gauss or more. The saturation magnetic flux density Bs of the metal-metalloid amorphous alloy is approximately 10,000 Gauss.

Therefore, metal-metal amorphous alloys such as Co--Zr and Co--Hf have been discovered as amorphous alloys having high saturation magnetic flux densities. However, in the case of the metal-metal amorphous alloy, the proportion of Zr or Hf is approximately 5 atomic %, for example.
Although it exhibits ^an extremely large saturation magnetic flux density of approximately 15,000 Gauss when It has become so.

Also, in order to lower the saturation magnetostriction constant λs mentioned above,
A Co-Zr-Nb based amorphous alloy containing Nb has also been proposed, but for this type of amorphous alloy,
For example, the saturation magnetostriction constant λs is zero when the proportion of Co is 93 atomic% and the composition is Zr:Nb=3:5, and the initial magnetic permeability is about 3000 or more (1MHz to 10MHz, hard axis direction), which shows good soft magnetic properties. However, in this case, a decrease in the saturation magnetic flux density Bs is observed, and the value of the saturation magnetic flux density Bs has become approximately 14000 Gauss or less.

As described above, a soft magnetic thin film that satisfies both the saturation magnetic flux density Bs and the saturation magnetostriction constant λs has not been found, and further improvements are desired.

[Purpose of the invention]

Therefore, the present invention was proposed in response to the above-mentioned demands in the technical field, and has a large saturation magnetic flux density Bs (more than 14000 Gauss) and a small saturation magnetostriction constant λs (+1.5×10 ^-6 (hereinafter) aims to provide an amorphous soft magnetic thin film.

[Summary of the invention]

The present inventors have conducted intensive research to develop an amorphous soft magnetic thin film with a large saturation magnetic flux density Bs and a small saturation magnetostriction constant λs. The present invention was completed by discovering that a magnetic thin film is suitable for this purpose, and is expressed by the composition formula Co _1-xy HfxPty, with a composition range of 0.04≦x≦0.07, 0.005≦y≦0.15. It is characterized by certain things.

That is, the amorphous soft magnetic thin film according to the present invention is
It is formed from a Co-Hf-Pt-based amorphous alloy material in which Pt is added to a Co-Hf-based amorphous alloy, which is a metal-metal amorphous alloy, and by adding the above-mentioned Pt. The saturation magnetostriction constant λs can be reduced without reducing the high saturation magnetic flux density of the Co-Hf amorphous alloy.

Here, in the above amorphous soft magnetic thin film,
The content of Pt and Hf is important, and these Pt and Hf contents are important.
If the Hf content is too high or low, it is difficult to improve both the saturation magnetic flux density Bs and the saturation magnetostriction constant λs.

For example, if the Hf content is less than 4 at %, there is a high risk of crystallization, and therefore there is a high possibility that an amorphous soft magnetic thin film will not be obtained. Also, above
If the Hf content is too high, a decrease in the saturation magnetic flux density Bs will be seen, and especially when trying to obtain a saturation magnetic flux density Bs of 14,000 Gauss or more, the Hf content should be 7 at% or less. is necessary.

On the other hand, although even a small amount of Pt added has the effect of lowering the saturation magnetostriction constant λs, it is practically preferable that the amount of Pt added is 0.5 atomic % or more. In addition, the saturation magnetostriction constant λs decreases as the amount of Pt added increases, but
If the amount of Pt added is too large, this Pt is expensive, so it is not only unfavorable from an economic standpoint, but also there is a risk that the saturation magnetic flux density Bs will decrease.

Therefore, as a practical range, it is preferable that the Hf content is 4 to 7 at%, the Pt content is 0.5 to 15 at%, and the balance is Co. That is,
When the amorphous soft magnetic thin film is expressed by the composition formula Co _1-xy HfxPty, it is preferable to set the composition range to be 0.04≦X≦0.07 and 0.005≦Y≦0.15.

By the way, the above-mentioned amorphous soft magnetic thin film can be produced by a liquid quenching method, a sputtering method, etc., but in particular, the above amorphous soft magnetic thin film can be used for a single magnetic pole head for perpendicular recording, a narrow gap spring head, etc. When used in applications, an extremely thin film is required, so the sputtering method is adopted. According to this sputtering method, it is easy to make the amorphous state, a thin film to a thick film with a thickness of several hundred angstroms to several mm can be produced, and the film has excellent adhesion. This is suitable for producing a soft magnetic thin film.

The above-mentioned sputtering method may be any conventional method, such as bipolar sputtering method, triode/quadrupole sputtering method, magnetron sputtering method, high frequency sputtering method, bias sputtering method, etc. , asymmetric AC sputtering method, etc.

Note that Co, which constitutes the above amorphous soft magnetic thin film,
The method for adjusting the amounts of each component element of Hf and Pt is as follows: (1) Weigh Co, Hf, and Pt to a predetermined ratio, and melt them in advance, for example, in a high-frequency melting furnace to form an alloy ingot. (2) Prepare a single Co element Co target and use this alloy ingot as a target.
Hf pieces are placed on the Co target, and these Hf pieces and
(3) A method of controlling the composition by adjusting the number of Pt pieces. (3) A method in which targets for individual elements of each component are prepared, and the sputtering speed is controlled by controlling the output (applied voltage) applied to each of these targets. Methods for controlling composition, etc.

In the amorphous soft magnetic thin film according to the present invention produced by the method described above, by adding Pt as a component, the saturation magnetic flux density Bs is 14000 Gauss or more and the saturation magnetostriction constant λs is +1.5. A composition region was found in which the composition is less ^than
(hard axis direction) and was found to be significantly improved compared to conventional Co-Hf amorphous alloys. moreover,
By selecting the above Hf and Pt contents, the saturation magnetic flux density Bs is 14500 Gauss or more, the saturation magnetostriction constant λs
It was also found that it is possible to obtain an amorphous soft magnetic thin film of +1.0×10 ^-6 or less.

〔Example〕

Next, examples of the present invention will be described.

Hf pieces and Pt pieces were placed on a Co target, and sputtering was performed under the following conditions while adjusting the number of Hf pieces and Pt pieces to grow an amorphous soft magnetic thin film on a glass substrate.

Sputtering conditions Ar gas pressure 7.0×10 ^-1 Pa Power 200W Formation speed 100-300Å/min Substrate Glass (water-cooled) Figure 1 shows the relationship between the composition of the obtained amorphous soft magnetic thin film and the saturation magnetic flux density Bs. Furthermore, the relationship between the composition of the obtained amorphous soft magnetic thin film and the saturation magnetostriction constant λs is shown in FIG.

In addition, in this Figure 1, the curve a is Bs=
Composition that yields 14000 Gauss, curve b is Bs=
The composition that yields 14500 Gauss, the curve c is Bs=
The compositions that yield 15,000 Gauss are shown respectively. Also, in Figure 2, curve A is λs = +3.0×10 ^-6
Curve B has a composition where λs = +2.0×10 ^-6 , Curve C has a composition where λs = +1.5×10 ^-6 , and Curve D has a composition where λs = +1.0×10 ^-6 . The composition of each is shown.

From these figures 1 and 2, the saturation magnetostriction constant λs gradually decreases by adding Pt,
It can also be seen that if Hf is set within a predetermined range, a high saturation magnetic flux density can be achieved at the same time.

For example, in order to achieve Bs≧14500 Gauss and λs≦2.0×10 ^-6 , when the composition of the amorphous soft magnetic thin film is Co _1-xy HfxPty, 0.05<x≦0.06, 0.01≦y. Just set it.

Similarly, in order to achieve Bs≧14500 Gauss, λs≦+1.5×10 ^-6 , it is sufficient to set 0.05<x≦0.06, 0.02≦y, and furthermore, Bs≧14500 Gauss, λs≦+
To achieve 1.0×10 ^-6 , 0.05<x≦0.06,
It is sufficient to set 0.03≦y.

Furthermore, if a higher saturation magnetic flux density Bs is required, for example to achieve Bs≧15000 Gauss, it is sufficient to set 0.04<x≦0.05 and 0.01≦y. In this case, λs≦2.0×10 ⁻⁶ .

Similarly, in order to further lower the saturation magnetostriction constant λs, for example, Bs≧15000 Gauss, λs≦
To achieve +1.5×10 ^-6 , 0.04<x≦0.05,
It is sufficient to set 0.02≦y, and in order to achieve Bs≧15000 Gauss and λs≦+1.0×10 ^-6 , 0.04<
It is sufficient to set x≦0.06 and 0.03≦y.

In this way, in the amorphous soft magnetic thin film of this example, by setting the contents of Hf and Pt as described above, it is possible to improve the saturation magnetostriction constant λs without reducing the saturation magnetic flux density Bs. is possible.

〔Effect of the invention〕

As described above, in the present invention, by adding Pt to Co and Hf, the saturation magnetic flux density Bs
It has become possible to obtain an amorphous soft magnetic thin film with a large magnetostriction constant λs and a small saturation magnetostriction constant λs.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram showing the composition dependence of the saturation magnetic flux density Bs in an amorphous soft magnetic thin film according to the present invention, and FIG. 2 is a characteristic diagram showing the composition dependence of the saturation magnetostriction constant λs.

Claims (1)

[Claims] An amorphous soft magnetic thin film represented by the composition formula 1 Co _1-xy HfxPty, and characterized in that the composition range is 0.04≦x≦0.07 0.005≦y≦0.15.