JPH01260805A - Magnetic thin film for thin film magnetic head - Google Patents

Abstract

PURPOSE:To obtain a thin film magnetic head which has excellent reading and writing performance for high coercive force and high line density magnetic recording medium by alternately laminating a 45 Permalloy thin film and an 80 termalloy thin film and specifying film thicknesses of respective thin films. CONSTITUTION:The total is composed of 5 layers or more in which a 45 Permalloy thin film composed of nickel of 40-50% and residual iron and an 80 Permalloy thin film composed of nickel of 75-85% and residual iron are laminated alternately, the film thickness of the 80 Permalloy thin film is in the range of 50-200nm and the film thickness of the 45 Permalloy thin film is 1-3times that of the 80 Permalloy thin film. The 80 Permalloy is high in magnetic permeability (mu)=2000, but is insufficient in writing performance for a metal coated medium with Bs=10KG. On the other hand, the 45 Permalloy is high in saturation magnetic flux density (Bs)=15.5KG, but insufficient in reading performance with mu=600. The head which has performance sufficient in reading and writing to the metal coated medium can be obtained by lamination of 45 Permalloy and 80 Permalloy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic thin film used as a magnetic material for a thin film magnetic head, and is particularly directed to a thin film magnetic head compatible with high density recording media.

[Background of the invention]

Nickel (Ni) is used as the magnetic pole material for thin film magnetic heads.
80 Permalloy 1 membranes consisting of 0% iron (Fe) and about 20% iron (Fe) are conventionally used.

For example, please refer to Japanese Patent Application Laid-Open No. 60-10410.

Since the 80 permalloy film has high magnetic permeability in the high frequency range, a thin film magnetic head using this film as a magnetic pole material has excellent read performance.

However, 80 permalloy has a saturation magnetic flux density of about 10K.
Because of its low G, thin-film magnetic heads using this material as the magnetic pole material have poor writing performance. In particular, when a high coercive force and high density medium such as a metal-coated medium is used, a thin film magnetic head using 80 permalloy as a magnetic material has insufficient writing performance.

[Purpose of the invention]

The object of the present invention is to provide a soft magnetic thin film that has sufficient magnetic permeability for reading and is sufficient for writing on recording media with high coercive force and high linear recording density such as metal coated media, and a thin film magnetic head using this as a magnetic pole material. is to provide.

[Summary of the invention]

Improving recording density in magnetic heads is always a technical challenge.

It is desired to improve the recording density of both rigid disks and floppy disks, and efforts are being made to improve both track density and linear recording density. The present invention relates to improving linear recording density.

Linear recording density is determined by recording medium and head characteristics. According to "Theory of Magnetic Recording" (written by Masaaki Nishiyo, published by Shokuhin Shoten), in terms of recording medium characteristics and magnetization reversal density, Wso...the half-width of the isolated reproduction waveform) (c...the coercive force of the recording medium Br...・Residual magnetization δ of the recording medium: Thickness of the recording medium.

That is, the magnetization reversal density (linear recording density) D5° is determined by the coercive force, residual magnetization, and thickness of the recording medium.

I)so can also be increased by reducing the residual magnetization and thickness, but these two parameters cannot be reduced very significantly from the viewpoint of reproduction output.

Therefore, I)so is mainly determined by the coercive force of the recording medium.

That is, the seed line recording density D5 at which the medium coercive force Hc increases
0 becomes larger.

Incidentally, when the medium coercive force He increases, it is necessary to increase the write magnetic field of the head, and the write magnetic field of the head is determined by the saturation magnetic flux density Bs of the head magnetic pole material. According to Karlquist's equation, the write magnetic field)(xmax is expressed as follows.

Here, Hg...in-gap magnetic field g...gap length d...head-medium amount separation length δ...medium thickness. Furthermore, the magnetic field Hg in the gap has the relationship: Hg≦Bs Bs... the saturation magnetic flux density of the magnetic pole material, and when other parameters are fixed, the write magnetic field Hxmax is determined by the saturation magnetic flux density Bs of the magnetic pole material.

Furthermore, according to a report by Nakanishi et al. (Tsuken Research Practical Report Vol. 28, No. 10, 1979, p. 149), the magnetic field required for erasing (overwriting) is three times the medium coercive force Hc.

Based on the above considerations, the coercive force Hc and linear recording density of magnetic recording media that are currently being used or will be used in the future are as follows. , and the saturation magnetic flux density Bs of the magnetic pole material that can be written on and retracted from it is shown in FIG.

According to this result, the magnetic pole material 80 permalloy conventionally used in thin-film magnetic heads has Bs=10KG and Co
rFetOs (Hc = 720 oe%Dao = 28
KBPI), but metal coated media (Hc=1500oe, DIIO=46KB)
PI) will result in insufficient writing. Therefore, a magnetic pole material having a higher saturation magnetic flux density Bs is desired.

45 Permalloy is the same binary Pe-Ni alloy as 80 Permalloy. This magnetic pole material has a saturation magnetic flux density BS=15
．． It is high at 5KG and has excellent writing characteristics. However, the magnetic permeability μ is as low as 600.

According to C, W, 5teel et al.
5teel.

J, C, Ma json: IEEE Tra
'ns, MagnMAG-8P, 503-505)
For writing, μ>100 is said to be a standard for suppressing deterioration of the Hx distribution.

According to the above-mentioned "Theory of Magnetic Recording" (written by Nishiyo), the reproducing head is required to have a core with magnetic permeability that is one order of magnitude higher than that of the recording head.

That is, when the magnetic permeability μ is less than 100, it becomes a region where reading and writing is not possible, when it is 100 to 1000, it is a region where only writing is possible, and when it is 1000 or more, it becomes a region where reading and writing is possible.

Figure 2 evaluates the performance of 80 permalloy and 45 permalloy based on these considerations.

That is, although 80 permalloy has a high μ of 2000, its writing performance is insufficient for metal-coated media at Bs210KG.

On the other hand, 45 permalloy is high at Bs=15.5KG, but μ=
600, which is poor in reading performance.

In the present invention, 45 permalloy and 80 permalloy are alternately laminated to obtain a laminated magnetic pole material having saturation magnetic flux density BS = 14 KG and μ = 1050. To provide a head that has satisfactory performance in both writing and writing.

This will be explained below using examples.

[Example 1] N15O, 7H20 (300j!/l), NiC6,
・6H,0(30,!i'/l and Fe25o,
-7H20 (30g/11) In addition, a plating solution containing H8BO3 and saccharin sodium was used.

By setting the plating current density to 30 mA/i, a 45 permalloy film can be obtained, and by setting the plating current density to 7 mA/c MIK, an 8
A zero permalloy film was obtained.

45 permalloy in the first, third and fifth layers, 80
FIG. 3 shows the relationship between the saturation magnetic flux density Bs and the magnetic permeability μ (measured at 4 MHz) with respect to the thickness of one layer of a film in which a total of five layers of Permalloy are laminated alternately as the second and fourth layers.

Note that the thickness of each layer of 45 Permalloy and 80 Permalloy is equal here.

From Figure 3, it was found that by setting the film thickness of one layer to 50 to 200 nm, a laminated ferromagnetic thin film having sufficient performance for reading and writing a metal coating medium of 14KG in Bs and μ = 1000 to 1o50 can be obtained. Ta.

[Example 2] A laminated film of a 45 permalloy film and an 80 permalloy film was formed by plating using the same plating solution and method as in Example 1.

FIG. 4 shows changes in the saturation magnetic flux density Bs and magnetic permeability μ when the film thickness ratio of the 45 Permalloy film to the 80 Permalloy film (film thickness IQQ nm-constant) was changed. 45 permalloy/
8o permalloy has Bs when the film thickness ratio is in the range of 1/1 to 3/1
It has been found that a laminated ferromagnetic thin film having sufficient performance for reading and writing medium-14KG, metal-coated media with μ=1000-1050 can be obtained.

[Example 3] A laminated film of a 45 permalloy film and an 80 permalloy film was formed by plating using the same plating solution and method as in Example 1.

The film thickness of 45 permalloy film and 80 permalloy film is 10
FIG. 5 shows the changes in the saturation magnetic flux density Bs and the magnetic permeability μ with respect to the total number of layers of the films alternately laminated at a constant rate of 100 nm.

If the total number of fine layers is 5 or more, BS = 13~14KG, μ
It has been found that a laminated ferromagnetic thin film sufficient for reading and writing metal-coated media with a magnetic field of 1,000 to 1,100 mm can be obtained.

[Example 4] Upper and lower inner magnetic pole thickness 2.1μ, track width 40μ, gap length 0.3μ, gap depth 2μ, and coil percentage number 50
A thin film magnetic head for a floppy disk (double coil) was fabricated.

Head A has 10 layers each of 45 permalloy and 80 permalloy.
A laminated ferromagnetic thin film having a constant thickness of 100 nm and a total of 21 layers was used as the magnetic pole material. Head B used an 80% permalloy single-layer film as a magnetic pole material. Head C used a 45% permalloy single-layer film as a magnetic pole material.

Table 1 shows the read/write performance of heads A, B, and C for metal coating media () (C: 15000e).
That is, it shows the output voltage and override characteristics. Head A shows excellent performance in both output voltage and override.

Head B lacks override, and head C lacks output voltage.

That is, only head A, whose magnetic pole material was a ferromagnetic thin film in which 45 permalloy films and 80 permalloy films were alternately laminated according to the present invention, exhibited sufficient read/write performance.

In each embodiment of the present invention, the laminated ferromagnetic thin film was formed by a plating method, but the object of the present invention can also be achieved by a PVD method such as sputtering or vacuum evaporation, or a CVD method such as plasma CVD or photo-CVD.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a thin film magnetic head having excellent read/write performance for high coercive force and high linear density magnetic recording media.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the relationship between the linear recording density of various magnetic recording media and the saturation magnetic flux density Bs of the head magnetic pole material that has writing performance on the linear recording density, and Fig. 2 is a diagram showing the relationship between the saturation magnetic flux density Bs of the head magnetic pole material,
Diagram showing the relationship between magnetic permeability μ and read/write performance of the head, Part 3
4 and 5 are diagrams showing the relationship between the formation factors of the laminated ferromagnetic thin film of the present invention, the saturation magnetic flux density Bs, and the magnetic permeability μ. Fig. 1 Wataru tO (2) Freezing level Ss (Ni G) Fig. 2 Pox Jiao Ping j Fig. 3 To 45 no V - Ma0i sword λ death no 0 Barmaro 4 welfare = /180
Permanent o4M thickness 1oonm -4' Fig. 5 11fk thickness 1100n -i

Claims (1)

[Claims] It consists of a total of five or more laminated films in which a 45 permalloy thin film consisting of 40 to 50% residual iron of nickel and an 80 permalloy thin film consisting of nickel with a residual iron of 75 to 85% are laminated alternately, and the film thickness of the 80 permalloy thin film is 50%. 200 nm, and the thickness of the 45 Permalloy thin film is 1 to 3 times the thickness of the 80 Permalloy thin film.