JPH0746655B2 - Soft magnetic thin film - Google Patents

Description

The present invention relates to a soft magnetic thin film suitable for use in, for example, a thin film magnetic head.

[Outline of Invention]

The present invention is a soft magnetic thin film in which Cr is added to an Fe-Co-Si-Al alloy, and a high saturation magnetic flux density Bs is determined by specifying its composition.
And a high magnetic permeability μ, and in particular, a soft magnetic thin film excellent in wear resistance is obtained.

[Prior Art] In various magnetic recording / reproducing apparatuses, there is an increasing demand for higher density recording and higher frequency, and correspondingly, magnetic recording media having high saturation magnetization and high coercive force are used. As this kind of magnetic recording medium, a so-called metal tape using a powder of a ferromagnetic metal such as Fe, Co, or Ni, a so-called vapor deposition tape formed by coating a ferromagnetic metal material on a base film, and the like are used. Has reached.

Along with this, a magnetic head for this type of magnetic recording medium is required to be made of a head material having high saturation magnetic flux density and high magnetic permeability, and from the requirement of high density recording,
The relative speed between the magnetic medium and the magnetic head tends to be faster, and as a result, it is chemically stable as well as having magnetic properties such as high wear resistance and excellent corrosion resistance as a head material. Therefore, it is required to have excellent mechanical properties.

As this magnetic material, it has high permeability and high saturation magnetic flux density.
It has been considered to use an amorphous magnetic alloy material containing Bs, but this amorphous magnetic alloy material has a difficulty in heat resistance, and its magnetic permeability greatly deteriorates due to long-term heating or thermal cycling. However, the regeneration efficiency becomes poor. In particular, since there is a high possibility of crystallization, it is not possible to apply a temperature of 500 ° C or higher for a long time, and for this reason, in the manufacturing process of the magnetic head, for example, glass fusion treatment at a temperature of 500 ° C or higher is required. There is a problem that it is not preferable to take the necessary steps.

Under such circumstances, research on soft magnetic materials exhibiting even better soft magnetic properties has been promoted. For example, in Tatsuharu Yamamoto and Kuki Chiba, “Journal of the Japan Institute of Metals”, Volume 14, B, No. 2 (1950). Have reported that an Fe-Co-Si based alloy material containing Fe, Co, and Si as main components exhibits excellent soft magnetic properties.

However, this Fe-Co-Si alloy material is extremely fragile and poor in practicality, and there is a problem in using it as it is as a core material of a magnetic head.

On the other hand, along with the high density recording, it is required to reduce the recording track width, and hence the track width of the working magnetic gap in the magnetic head, and to meet this requirement, particularly, the mass productivity is remarkably improved in the multi-track magnetic head. As a measure that can be measured, a thin film magnetic head using a thin film technique for forming a magnetic head core of a soft magnetic thin film on a non-magnetic or magnetic substrate is remarkably popularized. As a soft magnetic thin film of this kind, a sendust alloy thin film containing Fe, Al and Si as main components has been attracting attention.

Since this sendust alloy thin film has a high saturation magnetic flux density Bs and a relatively high hardness, it can be applied to a magnetic recording medium having a high residual magnetic flux density such as the metal tape described above. is there.

However, although this sendust alloy thin film has a relatively high hardness, it is inferior in wear resistance and corrosion resistance to, for example, a ferrite material.

[Problems to be solved by the invention]

The present invention has improved the above-mentioned various problems, and has a saturation magnetic flux density.
Bs and magnetic permeability μ do not decrease, coercive force Hc is small, magnetostriction λs is almost zero, magnetic anisotropy is small, and it has excellent magnetic properties and soft magnetism with excellent wear resistance. A thin film is provided.

[Means for solving problems]

In the present invention, chromium Cr is added to the magnetic thin film containing Fe, Co, Si and Al as the main components.

That is, the present invention is mainly composed of Fe, Co, Si and Al, and the composition thereof is 5 to 15 atom% of Co, 6 to 17 atom% of Si, 2 to 13 atom% of Al, and 0.5 to 10% of Cr. 7 atomic% and the balance Fe.

The thickness of the soft magnetic thin film of the present invention having the above composition is preferably 10 Å or more and 1 mm or less, and more preferably 10 Å or more and 100 μm or less.

[Operation] As described above, the soft magnetic thin film according to the present invention contains Fe, Co, Si and Al as the main components, and by adding Al, Fe--Co--
Compared to Si-based soft magnetic material, it is possible to obtain a soft magnetic material having high magnetic permeability with small coercive force and magnetostriction, but in the present invention, it is characterized by containing Cr in it. Thereby, the wear resistance is particularly improved.

According to the experiments by the present inventors, the content of Co is 5 to 15 atom%.
Outside the range, the coercive force increased and the magnetic permeability decreased.

Regarding Si and Al, Si is 6 to 17 atomic%, A
l must be 2 to 13 atomic%. This is Si and Al
When the content of is out of these ranges, for example, the coercive force becomes large and it cannot be used as the core material of the magnetic head, and at the same time, the saturation magnetic flux density and the magnetic permeability decrease. On the other hand, in the above range, low coercive force, high saturation magnetic flux density and high magnetic permeability can be achieved, and further zero magnetostriction can be obtained.

Regarding Cr, if Cr is less than 0.5 atom%, high wear resistance cannot be obtained, and if it exceeds 15 atom%, magnetic properties such as saturation magnetic flux density are deteriorated.

〔Example〕

Example 1 Pure iron having a purity of 99.9% or more, electrolytic cobalt, chromium, aluminum, and silicon having a purity of 99.999% or more were weighed, respectively, and in an alumina crucible in an alumina crucible using a high frequency induction heating furnace. It was melted and a target base material having a diameter of 105 mm was cast. Both surfaces of this base material were ground by a surface grinder to prepare a sputtering target having a thickness of 5 mm.

Using this target, a planar magnetron type high frequency sputtering apparatus was used to perform sputtering with a thickness of 2 μm on a crystallized glass substrate.

The conditions of this sputtering were as follows: ultimate gas pressure of 6.0 × 10 ^-6 Torr substrate temperature without heating, Ar gas pressure of 7.0 × 10 ^-3 Torr, 1 hour of preliminary sputtering, and 1 hour of sputtering time.

The substrate on which the sputtering thin film was formed was
After vacuum annealing for 1 hour, the magnetic properties of the thin film, that is, the saturation magnetic flux density Bs, the coercive force Hc, and the magnetic permeability μeff at a frequency of 5 MHz were measured by changing the film composition. The amount of wear was measured for each composition. The results are shown in FIG. The Fe-Co-Si-Al alloy thin film to which Cr is added becomes a crystalline alloy thin film by heat treatment at a temperature of 500 ° C for 1 hour.

The amount of wear was measured by making a dummy head (1) for measuring the amount of wear as shown in FIG. This head (1) has a width W of 3.0 mm and a thickness t of 0.5 mm and forms a front surface which is in contact with a cylindrical magnetic medium, and a thin film to be measured (2) is deposited on this surface. This head (1) is placed on the base plate of the rotary magnetic head drum for 1 inch VTR, and 80μ from the drum surface.
It was projected at ± 5 μm and connected to a γ-Fe ₂ O ₃ based magnetic medium. In this case, the film surface (2) was measured every 5 hours of tape running time.
The amount of wear was measured using a microscope (magnification: 400 times) at a distance from the marker (3) attached to a predetermined position of the head (1). For the sputtering of the film to be measured onto this dummy head, the ultimate gas pressure was 6.0 × 10 ⁻⁶ Torr, the substrate temperature was 300 to 400 ° C., the Ar gas pressure was 7.0 × 10 ⁻³ Torr, the presputtering time was 1 hour, and the sputtering time was 4 to 5 hours. . Then, for each composition of 1, six dummy heads were used to perform the measurement, and the average wear amount is shown in FIG.

As can be seen from FIG. 1, the soft magnetic thin film of the present invention made of a Cr-added Fe-Co-Al-Si system can improve the wear amount per hour without deteriorating the magnetic properties. There is.

Further, in the above-mentioned soft magnetic thin film according to the present invention, various elements may be added as an additive in order to further improve various properties such as corrosion resistance and abrasion resistance. As the element used as this additive, Ti, Zr, IVa group elements such as Hf, V, Nb,
Va group elements such as Ta, VIa group elements such as Mo and W, VIIa group elements such as Mn, and platinum group elements of the fifth period platinum group elements, that is, Ru, Rh, Rd, and sixth period platinum group elements. , Ie Os, I
r, Pt and the like can be mentioned, and one or more of these additives can be combined and added in the range of 0 to 10% by weight with respect to the magnetic thin film.

〔The invention's effect〕

As described above, according to the soft magnetic thin film of the present invention, the saturation magnetic flux density is not lowered and the coercive force is not increased, the magnetic permeability is high and the wear resistance is excellent. Since it is possible to obtain a soft magnetic thin film that is free from instability and has excellent heat resistance, it is extremely profitable when used as a thin film magnetic core of a thin film magnetic head for high density recording, for example.

[Brief description of drawings]

FIG. 1 is a table showing the composition of the soft magnetic thin film and the measurement results of each characteristic, and FIG. 2 is an enlarged perspective view of the wear amount measuring dummy head. (1) is a dummy head, and (2) is a thin film to be measured.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Yoshitaka Ochiai 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Hideki Matsuda 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Inventor Hiroshi Iwasaki 6-735 Kitashinagawa, Shinagawa-ku, Tokyo Sony Corporation (72) Inventor Koichi Aso 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Soni -Incorporated (56) Reference JP 58-67845 (JP, A) JP 55-2783 (JP, A) JP 53-70021 (JP, A)

Claims (1)

[Claims] 1. A crystalline alloy thin film containing Fe, Co, Si and Al containing Cr
Is added, Co is 5 to 15 atom%, Si is 6 to 17
Atomic%, Al 2-13 atomic%, Cr 0.5-7 atomic%, balance F
A soft magnetic thin film having a composition of e.