JPS62104111A - Soft magnetic thin film - Google Patents

Abstract

PURPOSE:To contrive the improvement in the resistance to corrosion and abra sion without deteriorating a soft magnetic characteristic by specifying the compo sition ranges of Co, Si and Al and further adding Ru of specified atm% in an alloy thin film of Fe-Co-Si-Al group. CONSTITUTION:This soft magnetic thin film is mainly composed of Fe, Co, Si and Al and the composition ranges of said Co, Si and Al are 1-15atm% Co and 10-20atm% Si, 8-15atm% Al. Furthermore, Ru of 0.1-10atm% is included. In case of the composition of the soft magnetic thin film as Fe68Co10 Al9Si13-xRux (figures represent atm%), when the quantity of abrasion 15 examined while changing the addition quantity (x) of Ru, the quantity of abrasion becomes extremely small according to an increase in addition quantity of Ru, for example, even after the 30hr running of a magnetic head and more sperior resistance to abrasion than Sendust can been observed when Ru is 4atm%.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a soft magnetic thin film, and in particular, to a soft magnetic thin film.
The present invention relates to improving the corrosion resistance of -Co-3i -Affi alloy thin films.

[Summary of the invention]

In the present invention, in the Fe-Co-3i-AJ alloy thin film, the composition range of Co, Si and Afi is 1 to 15, respectively.
At %, 10 to 20 at %, 8 to 15 at %, and further adding 0.1 to 10 at % of Ru in an attempt to improve corrosion resistance and wear resistance without deteriorating soft magnetic properties. It is something.

(Prior Art) For the purpose of increasing recording density and quality in magnetic recording, a magnetic recording medium 1 having a high coercive force, for example, F is added to magnetic powder.
So-called alloy-coated metal tapes using metal magnetic powder made of metals or alloys such as e, Co, and Ni have been developed, and have been used in audio tape recorders, so-called 8 mm VTRs (8 mm video tape recorders), etc. Practical use is progressing in the field of consumer magnetic recording.

Therefore, in order to sufficiently magnetize such a magnetic recording medium, the core material of the magnetic head is required to have a sufficiently high saturation magnetic flux density commensurate with the coercive force of the medium. In addition, especially when recording and reproducing are performed using the same magnetic flux, the material needs to have not only the above-mentioned saturation magnetic flux density but also a sufficiently high magnetic permeability in a commonly used frequency band.

It is well known that Fe-Al-3i alloy (Sendust alloy) has been known as a core material that satisfies such basic magnetic properties and is in practical use.

However, in materials with excellent soft magnetic properties such as this Sendust alloy, magnetostriction λS and magnetocrystalline anisotropy K
It is desirable that both values be around zero, and the material composition that can be used in the magnetic head is determined by taking these two values into consideration. Therefore, the saturation magnetic flux density is also uniquely determined according to this composition, and in the case of Sendust alloy, the limit is 10 to 11 gauss.

Alternatively, instead of the Sendust alloy mentioned above, an amorphous magnetic alloy material (so-called amorphous magnetic alloy material) has been developed that has a high saturation magnetic flux density with less decrease in i3 magnetic flux density in the high frequency region. Even alloy materials have a saturation magnetic flux density of about 12 Gauss, and are thermally unstable and have a high possibility of crystallization, so it is not possible to apply temperatures over 500°C for a long time. There are process limitations when using it for magnetic heads that require various heat treatments.

(Problems to be Solved by the Invention) Under these circumstances, research into soft magnetic materials exhibiting even better soft magnetic properties has been progressing. In the book, Fe,
We have proposed a Fa-Co-3i-Al based soft magnetic thin film that has Go, Si, and Al as its main components and has excellent soft magnetic properties and thermal stability.

The present invention is directed to this Fe-Co-3i-AI soft magnetic FI [
This aims to further improve the corrosion resistance of #.

That is, the present invention has a higher saturation magnetic flux density than Sendust alloy, and also has excellent corrosion resistance.

The purpose of the present invention is to provide a soft magnetic thin film having thermal stability.

[Means for solving problems]

The inventors of the present invention have conducted extensive research to solve the above-mentioned problems, and have found that adding a predetermined amount of Ru improves corrosion resistance.

We have found that it is effective in improving wear resistance and does not impair soft magnetic properties.

The soft magnetic thin film of the present invention was completed based on such knowledge, and includes Fe, Go, and SL.

Al is the main component, and the composition ranges of Co, Si and Al are 1 to 15 at% Co, 1O to 20 at% Si, respectively.
, 8 to 15 atom % Af, and further contains 0.1 to 10 atom % Ru.

Addition of Ru is extremely effective in improving corrosion resistance and abrasion resistance. For example, when the composition of a soft magnetic thin film is
oA 1 *S i +*-xRu
When the amount of wear was investigated by changing the amount of wear, as shown in FIG. 1, it showed a remarkable effect in reducing the amount of wear. In other words, when a soft magnetic thin film is processed into a magnetic head and a magnetic tape is run, the amount of wear increases as the running time increases, but as the amount of Ru added increases, for example, after running for 30 hours, The amount of wear is extremely small, and when Ru is 4 atomic%,
It was found that it exhibits better wear resistance than Sendust.

In addition, when we directly replaced a part of Fe with Ru and investigated the change in the saturation magnetic flux density, we found that as shown in Figure 2, the saturation magnetic flux density slightly decreased as the amount of Ru substitution increased, but Cr
The rate of decrease is extremely small compared to when replaced with
It was found that it is smaller than when replaced with Si or AI.

In the present invention, the amount of Ru added is set to 0.1 to 10 atom% because if the amount added is less than 0.1 atom%, a sufficient effect in improving wear resistance cannot be expected. This is because if it exceeds 10 atomic %, the soft magnetic properties will deteriorate and the saturation magnetic flux density will decrease, and the original meaning will be lost.

On the other hand, in the soft magnetic thin film of the present invention, in order to ensure predetermined magnetic properties, Fe is used as a basic component.

For Co, Si, An, Col ~ 15 atomic%, 5
ilo~20 at%, Al8~15 at%.

The remainder is Fe. When these basic components are outside the above composition range, it becomes difficult to ensure magnetic properties such as saturation magnetic flux density, magnetic permeability, and coercive force.

Therefore, if the composition of the soft magnetic thin film of the present invention is expressed by the formula % (wherein a, b, c, d, and e each represent the composition in atomic %), the composition range is 0. 1≦b≦10 1≦C≦15 10≦d≦20 8≦e≦15 a+b+c+d+e=100.

Although various methods can be considered for manufacturing the above-mentioned soft magnetic thin film, vacuum thin film forming technology is particularly preferred.

The techniques for forming this vacuum thin film include sputtering, ion blasting, and vacuum evaporation.

Examples include cluster ion beam method.

In addition, as a method for adjusting the composition of each of the above component elements, 1) Weigh Fe, Ru, Go, Si, and A# in a predetermined ratio, and melt them in advance in, for example, a high-frequency melting furnace. A method in which an alloy ingot is formed and this alloy ingot is used as an evaporation source; ii) A method in which evaporation sources for a single element of each component are prepared and the composition is controlled by the number of these evaporation sources; A method of preparing evaporation sources of a single element and controlling the output (applied voltage) applied to these evaporation sources to control the evaporation speed and composition; iv) A method of implanting other elements while depositing an alloy as an evaporation source. , etc.

Note that the soft magnetic thin film formed by the above-mentioned vacuum thin film forming technology has a slightly high coercive force in its original state and good soft magnetic properties cannot be obtained, so heat treatment is performed to reduce the distortion of the film. It is preferable to remove it to improve the soft magnetic properties.

[Effect]

As described above, the addition of Ru to the Fe-Co-3i-Ajj alloy whose basic components are Fe, Co, Si, and AI has a significant effect on improving wear resistance and corrosion resistance. In addition, there is almost no deterioration of soft magnetic properties due to the addition of Ru,
The decrease in saturation magnetic flux density is also significantly small.

〔Example〕

Hereinafter, specific examples of the present invention will be described, but the present invention is not limited to these examples.

First, Fe, Ru, Co, Si, and Alt were each weighed to have a predetermined composition ratio, melted and cast using a high-frequency induction heating furnace in an argon atmosphere, and then machined using a surface grinder. An alloy target for sputtering with a diameter of 4 inches and a thickness of 41 m was obtained.

Next, using this alloy target, an argon partial pressure of 5X 10-3T was applied using a high-frequency magnetron sputtering device.
Sputtering was performed under conditions of 300 W input power and a thin film with a thickness of about 1 μm was obtained on a water-cooled crystallized glass substrate (manufactured by Hoya Glass Co., Ltd., trade name: HOY8 PEG3130C).

Further, this 54 film was annealed at a temperature of Ta in a vacuum of I x 10-' Torr or less for 1 hour, and then slowly cooled to obtain a soft magnetic thin film.

According to the method described above, samples 1 to 3 were prepared by setting the composition ratio of the alloy target to the values shown in the following table.

For each sample obtained, the film composition of the soft magnetic thin film was analyzed, and the saturation magnetic flux density Bs, coercive force 1 (c.

Magnetic permeability μ (value at I M llz), magnetostriction, II
Abrasion and corrosion resistance were investigated.

Here, the saturation magnetic flux density BS is measured using a sample vibrating magnetometer (■SM).
, resistance (51 force Hc was measured with a B-H loop tracer of AC 10 llz, and rA C11 rate μ was measured with a figure-8 coil type ILT rate meter.The film thickness of each sample was determined by thinly vapor-depositing aluminum on the sample surface. Then, it was determined by using a multi-interference film thickness meter to determine the step difference between the film and the substrate by α1.Furthermore,
Compositional analysis of each sample was performed using EPMA (Electro
n Probe Micro-analysis) method.

The amount of wear was determined as follows. That is, first, a pseudo-imaging head made of ferrite was prepared as a substrate, and a soft magnetic thin film having a thickness of 18 μm was formed on the tip of the head chip under the same spuck conditions as described above. The video tape recorder with a tape width of 1 inch (relative speed 2
5.6 m / 5ee) with a track width of 9.5 mm and a protrusion of 180 μm, and r-FezO
A magnetic tape containing S as a magnetic powder was allowed to stand for 30 hours, and the amount of film reduction was determined by photographic observation using a microscope.

The corrosion resistance of each sample was determined by observing the surface of the membrane after being immersed in 1N saline at room temperature for one week.

The corrosion resistance was evaluated based on the following surface conditions.

A: There is no change in the g1 surface and the mirror surface is maintained.

B: A state in which a thin layer of rust has formed on the film surface.

C: A state in which thick rust has occurred on the film surface.

D: A state in which rust has occurred to the extent that the film itself disappears.

The results are shown in the table below. For comparison, the values for Fe-Co-3i-Al alloy (excluding Ru) formed in the same manner as the above method were also used as comparative samples 1 to 3. It was measured.

(Left below) From this table, it can be seen that for each sample to which the present invention is applied,
In particular, remarkable improvement effects were seen in corrosion resistance and wear amount.
In addition, regarding the saturation magnetic flux density, 33 magnetic flux density, and coercive force, Fe
It was found that it is comparable to Co-3i-Aff alloy.

〔Effect of the invention〕

As is clear from the above description, Fa, Co.

Fe-Co-3i-Aj with Si and Aj+ as basic components
! By adding Ru to the alloy, corrosion resistance and wear resistance can be significantly improved. Further, the addition of Ru does not cause deterioration of soft magnetic properties or decrease of saturation magnetic flux density.

Therefore, it is possible to provide a soft magnetic thin film that has excellent practical properties such as corrosion resistance and abrasion resistance, as well as excellent magnetic properties, and can be said to have extremely high practical value as a core material of a magnetic head.

[Brief explanation of drawings]

Figure 1 shows F ehsc OloA /9S i 1. −
11RLllll is a characteristic diagram showing the relationship between Ru addition i1x and wear amount, and FIG. 2 is a characteristic diagram showing the change in saturation magnetic flux density due to Ru substitution in comparison with the case of Cr addition.

Claims (1)

[Claims] The main components are Fe, Co, Si, and Al, and the Co, S
The composition range of i and Al is 1 to 15 at% Co, respectively.
10 to 20 at% Si, 8 to 15 at% Al,
A soft magnetic thin film further comprising 0.1 to 10 atomic % of Ru.