JPH03183743A - Soft magnetic film - Google Patents

Abstract

PURPOSE:To easily control the anisotropy of the soft magnetic film and to provide it with low coercive force and high saturation magnetic flux density by specifying the compositional range of each element in a quaternary alloy of Fe, Co, Ni and Cu. CONSTITUTION:The soft magnetic film is formed of a compsn. expressed by (Fe, Co)xNiyCuz, and the ratio of Co occupied in the (Fe, Co) is regulated to 30 to 80 atomic %. By atomic %, 40<=x<=80, 15<=y<=50 and 5<=z<=30 are satisfied. The soft magnetic film is film-formed by a vapor plating technique such as sputtering and is transformed into a magnetic core of a thin film magnetic head or the like. In this way, soft magnetic properties superior to those of a 'Peamalloy(R)' can be obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a soft magnetic film suitable for use as a magnetic core of a thin-film magnetic head.

[Summary of the invention]

The present invention aims to realize good soft magnetic properties by specifying the composition range of each constituent element in a quaternary alloy consisting of Fe, Co, Ni, and Cu.

[Conventional technology]

Permalloy (FeNi alloy) has been mainly used as a material for a magnetic core forming a closed magnetic path in thin-film magnetic heads and the like that perform recording and reproduction on so-called hard disks.

This is because the permalloy has excellent soft magnetic properties and its anisotropy can be easily controlled.

Incidentally, it is a well-known fact that higher density is being promoted in the field of magnetic recording, and it is natural that higher performance is required of the thin film magnetic head in response to this trend.

For example, as recording density increases, the coercive force of magnetic recording media increases, and therefore it is desired that soft magnetic films used in thin film magnetic heads have a high saturation magnetic flux density. At the same time, it goes without saying that it is necessary to have excellent soft magnetic properties, that is, a low coercive force.

Until now, research has been progressing in various fields regarding soft magnetic materials used in magnetic heads, and in fact, soft magnetic films such as Sendust and amorphous alloys have high saturation magnetic flux densities of 10 Gauss or higher, and Soft magnetic films with special characteristics have also been developed.

[Problem B to be Solved by the Invention] However, it is difficult to control the anisotropy of these soft magnetic films, and they are unsuitable as soft magnetic films used in thin film magnetic heads that perform recording and reproduction on, for example, hard disks. . Generally, in a thin film magnetic head, a soft magnetic film is given uniaxial magnetic anisotropy, the axis of easy magnetization is directed in the track width direction of the recording medium, and the axis of difficult magnetization is set in the excitation direction.
It is necessary to increase magnetic permeability in a high frequency region by causing magnetization reversal by magnetization rotation.

Therefore, the present invention was proposed in view of the above-mentioned conventional situation, and an object of the present invention is to provide a soft magnetic film whose anisotropy can be easily controlled, and which also has a low coercive force and a high saturation magnetic flux density. shall be.

[! Means to solve problem i]

As a result of intensive research to achieve the above-mentioned objective, the present inventors found that a quaternary alloy consisting of Fe, Co, Ni, and Cu has a face-centered cubic structure and the anisotropy can be easily controlled. In addition, they discovered that by specifying the composition, it is possible to achieve soft magnetic properties that far exceed those of permalloy.

The present invention has been developed based on this knowledge, and has Al1 consisting of (Fe, Co), Ni, and Cut, and has a composition range of 40 at%≦x≦80 at%, 15 at% ≦y≦50 atomic% 5 atomic%≦z≦30 atomic%, and the proportion of Co in (Fe, Co) is 30 to 30 atomic%.
It is characterized by being 80 atomic %.

That is, if the soft magnetic film of the present invention is further generalized, (F e H,, @CosLN 1 yCIJg40 atomic%≦x≦80 atomic% 15 atomic%≦y≦50 atomic% 5 atomic%≦z≦30 Atomic % 0.3≦m≦0.8.

The above-mentioned composition range was determined in consideration of soft magnetic properties, and if it is outside this range, the coercive force below I (Oe) or 1
It is not possible to achieve a high saturation magnetic flux density of Gauss or higher.

Note that the soft magnetic film of the present invention may contain additional elements in addition to the quaternary alloy. Although the type of additive element does not matter, examples include Mn, 5tCr, and Nb.

However, if too large amounts of these additive elements are added, the saturation magnetic flux density tends to decrease, so there is naturally an upper limit to the amount added, but normally there is no problem as long as it is 10 atomic % or less.

The soft magnetic film of the present invention is formed by a so-called gas phase plating technique such as sputtering, and is used as a magnetic core of a thin film magnetic head. When forming a film, the film thickness may be 0.3 μm or more, and sputtering may be performed using an alloy target prepared in advance so that the ratio of each atom falls within the above range, or It is also possible to prepare targets individually and control the composition by adjusting their area, applied power, etc. Especially when the former method is adopted, the &lI between the target composition and the M &l
The relative deviation is about 1% or less for each atom, and since they almost match, it is suitable for mass production, for example.

[Example〕 The present invention will be explained below based on specific experimental results.

130 Higashijo In this experimental example, the optimal range of the soft magnetic properties (coercive force and saturation magnetic flux density) of the thin film magnetic material tclll was investigated using a pseudo-ternary system of Ni, Cu, and Fe-Go.

A sputtering method was used for film formation, and the sputtering conditions are as follows.

Sputtering conditions RF magnetron sputtering target: Alloy target (diameter 100mm) Ultimate vacuum: 2.0X10-”Torr Input power:
300W Ar gas pressure: 2 mTorr A film was formed on a glass substrate under the above conditions to a thickness of 1 μm, and this was used as a sample. Furthermore, the film composition of the sample was almost the same as that of the target.

The soft magnetic properties were evaluated by measuring the coercive force Hc and the saturation magnetic flux density Bs. The coercive force Hc is measured using a B-H loop tracer [unit: Oersted, (Oe)]
), and the saturation magnetic flux density Bs was measured using a vibrating sample magnetometer (VSM) [unit: kilogauss (kG)].

Figure 1 is a pseudo ternary composition diagram showing isocoercive force lines in a pseudo ternary system of Fee, tCoe, s, Ni, and Cu, and Figure 2 is a pseudo ternary composition diagram showing the isocoercive force lines in a pseudo ternary system of Fee, tCoe, s, Ni, and Cu. Pseudo ternary composition diagram showing isocoercive field lines in a ternary system, Figure 3 is F
Fig. 4 is a pseudo-ternary composition diagram showing isocoercive field lines in a pseudo-ternary system of Co, 1, Ni, and Cu.
c is a pseudo-ternary composition diagram showing isocoercive force lines in a pseudo-ternary system of Oo, l, Ni, and Cu. In each drawing, the numerical values on the lines of equal coercive force indicate the values of the coercive force Hc on the lines of equal coercive force, and the unit is Oersted (Oe).The line a to wAd represents the saturation magnetic flux density Bs. The straight line a is the saturation magnetic flux density B S =10k
The G line is a straight line, the saturation magnetic flux density B S = 12k
G line, direct vAc is saturation magnetic flux density B S = 14
kG line, the straight line d is the saturation magnetic flux density B s = 16
Each line represents kG.

No matter which drawing you look at, Ni is 15 to 50 atomic%, Cu
By setting 5 to 30 at%, the coercive force Hc 1 (O
e) It was found that the following soft magnetism was achieved and a high saturation magnetic flux density of 10 kG or more was obtained.A representative sample was prepared based on the results of Experimental Example 1.
The properties were compared with that of permalloy produced under the same conditions, and the effects of heat treatment were also investigated. The sputtering conditions for the sample were the same as in Experimental Example 1, and a 1 μm thick quaternary alloy film was formed on a glass substrate.

The composition of the target used was FegsCotsNi4eCu+e (values are atomic %), and the analysis results of the obtained film &II were as follows:
, c O! S, IN iao, zcu+e, + (values are atomic %).

FIG. 5 shows the magnetization curve of the prepared sample.

The coercive force Hc is 0.16 (Oe), and the saturation magnetic flux density Bs is 13 kG.

On the other hand, permalloy film (Fe*
The coercive force Hc of eNL* (values are atomic %) is 20 (
Oe), the saturation magnetic flux density Bs was 9.8 kG, and it was found that the sample to which the present invention was applied was significantly superior in terms of soft magnetic properties.

Next, the sample was annealed in vacuum at 300° C. for 1 hour, and the coercive force He in the as-sputtered state and the coercive force Hc after the heat treatment were compared. As a result, the coercive force Hc in the as-sputtered state was 0.16 (Oe), and the coercive force Hc after heat treatment was 0.21 (Oe), at 300°C.
No deterioration of properties was observed after a certain amount of heat treatment.

Actually lmu 4 In this experimental example, Mn, Si, and Cr were added to the above-mentioned system.

Samples were prepared under the same conditions with the addition of Nb, and the influence of the added element was investigated.

The composition and coercive force Hc of each sample are shown on the firebox.

(Left below) As is clear from this table, there is no significant change in soft magnetism for any of the additive elements.

(Effect of the invention) As is clear from the above explanation, in the present invention,
Since the composition range of the quaternary alloy consisting of Fe, Co, Ni, and Cu has been specified, it is possible to achieve low coercive force and high saturation magnetic flux density at the same time, making it possible to create a soft material with soft magnetic properties far superior to permalloy. It is possible to provide a magnetic film.

Furthermore, since the soft magnetic film of the present invention has a face-centered cubic structure, it is easy to control anisotropy, and it is useful, for example, as a magnetic core material for a thin-film magnetic head that performs recording and reproduction on a hard disk. .

[Brief explanation of drawings]

Figure 1 is a pseudo-ternary composition diagram showing isostatic tB lines of force in a pseudo-ternary system of Feo, 7Coo, i, Ni, and Cu.
Figure 2 is a pseudo-ternary composition diagram showing isocoercive field lines in a pseudo-ternary system of Feo, 5Coo, s, Ni, and Cu, and Figure 3 is a pseudo-ternary composition diagram showing isocoercive force lines in a pseudo-ternary system of Fe 61CoO-7, Ni, and Cu. Pseudo ternary composition diagram showing magnetic field lines, Figure 4)"e6
．． zC06,e is a pseudo ternary composition diagram showing the isocoercive force lines in a pseudo ternary system of Ni and Cu. FIG. 5 is a characteristic diagram showing the magnetization curve of a typical sample to which the present invention is applied.

Claims (1)

[Claims] Having a composition of (Fe, Co)_xNi_yCu_z,
The composition range is 40 atomic%≦x≦80 atomic%, 15 atomic%≦y≦50 atomic%, 5 atomic%≦z≦30 atomic%, and the proportion of Co in (Fe, Co) is 30 to 30 atomic%.
A soft magnetic film characterized by having a content of 80 atomic %.