JPS6242328B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a magnetic head made of a Co-based amorphous alloy.

When a crystalline material is used as a magnetic head material, it is necessary not only to have a high magnetic flux density, but also to make both the magnetocrystalline anisotropy and the magnetostriction constant as zero as possible. In this regard, since amorphous alloys are considered to have no magnetocrystalline anisotropy, it is considered that only the magnetostriction constant should be made zero or close to zero. however,
Conventionally, when approaching zero, no consideration was given to whether the sign of the magnetostriction constant was preferably positive or negative. This amorphous alloy is usually obtained in the form of a long tape sample with a thickness of about 30 to 60 μm using the roll quenching method. Due to demand, polishing of the tape surface is often performed as post-processing. Therefore, if the magnetostriction constant is not zero, the magnetic head will be in a state where complex external stress is applied due to various treatments or processing (e.g., polishing, adhesion, resin molding, etc.) performed during the manufacturing process as described above. That is, the magnetic head is used with the external stress remaining inside the magnetic head. Since such stress is combined with the magnetostriction constant and causes induced magnetic anisotropy in complex directions, it generally does not reproduce the head properties (especially magnetic permeability) that are commensurate with the material properties, but rather causes the head properties to deteriorate. lead to.

The present invention has been made in view of the above-mentioned problems, and consists of a core half made of an amorphous magnetic alloy having a positive magnetostriction constant of 2.2×10 ^-6 or less, and a core half formed by a non-magnetic gap. This relates to magnetic heads that are butted against each other.

By using an amorphous alloy having a magnetostriction constant within the range specified by the present invention for the magnetic head,
Even if induced magnetic anisotropy in a complicated direction occurs due to external stress during head fabrication as described above, the induced magnetic anisotropy due to the sliding of the magnetic tape cancels this out, and the magnetic tape The polishing direction due to sliding, that is, the magnetic path direction, becomes the axis of easy magnetization,
A magnetic head with excellent reproduction characteristics can be obtained. That is, the characteristics (high magnetic permeability, high magnetic flux density, etc.) of the amorphous magnetic alloy material body can be utilized.

In the method for manufacturing a magnetic head according to the present invention,
Preferably, the surface of the amorphous alloy is etched away by about 1.5 microns or more. Furthermore, this method is applicable not only to Co-based amorphous alloys but also to all low magnetostriction amorphous alloys that can generally be used as magnetic head materials. Furthermore, this method is particularly effective when the thickness of the amorphous alloy is about 40 microns or less.

Hereinafter, the present invention will be explained in detail with reference to examples.

First of all, so that each composition (atomic ratio) will be described later,
Fe, Co, Si, B, and Ni were each weighed, and the mixture was melted in a high-frequency heating furnace to create a master alloy. Using this master alloy as a raw material, the raw material was quenched using a rolling quenching device previously proposed by the applicant in Japanese Patent Application No. 52-22937 to prepare a tape-shaped sample. It was confirmed by X-ray diffraction that the obtained tape-shaped sample was amorphous. A disk-shaped sample was punched out from this tape-shaped sample using an ultrasonic processing machine, and its magnetostriction was measured using a strain gauge method. At that time, the magnetostriction constant λ
are the expansion and contraction rates when a magnetic field is applied in the gauge direction and in the direction perpendicular to it, respectively (Δl/l) and (Δl/l)
As ⊥, it was determined from the general formula: λ=2/3 {(Δl/l)−(Δl/l)⊥)}.

Next, a corner piece was cut out from the tape-shaped sample, and the surface of this corner piece was polished in one direction with abrasive paper. Furthermore,
In order to improve the reflectance of the polished surface, polishing was performed in the same direction as described above using a tape coated with fine-grained alumina. Then, a 50 Hz excitation field was applied using a magneto-optical Kerr effect device to investigate the magnetization process of the polished surface.

Example 1 For a composition of Fe ₇ Co ₇₃ Si ₄ B ₁₆ , the Kerr hysteresis loops when an excitation field is applied parallel to and perpendicular to the polishing direction are shown in FIGS. 1 and 2, respectively. The magnetostriction constant was λ〓2.2×10 ^-6 .

From the very square loop shown in Figure 1 and the bent loop shown in Figure 2, magnetic anisotropy is produced by polishing, with the polishing direction being the axis of easy magnetization. I understand. Loops of this nature were observed all over the surface of the specimen. or,
As a result of the study, it was confirmed that the easy axis of magnetic anisotropy generated by this polishing occurs regardless of the polishing direction relative to the original amorphous tape.

Example 2 For the composition Fe ₄ . ₇ Co ₇₀ . ₃ Si ₁₅ B ₁₀ , the Kerr hysteresis loops when an excitation field is applied parallel to and perpendicular to the polishing direction are shown in Figs. 3 and 4, respectively. Ta. The magnetostriction constant λ was almost zero or slightly positive.

From FIGS. 3 and 4, results similar to those described in Example 1 were observed, that is, the occurrence of magnetic anisotropy having an axis of easy magnetization in the polishing direction.

Further, in the case of random polishing in which the polishing direction was not unidirectional, a loop as shown in FIG. 5 was observed almost independently of the direction of the observed magnetic field.

Example 3 The composition Fe ₄ . ₇ Co ₇₅ . ₃ Si ₄ B ₁₆ was measured, and the same results as in Examples 1 and 2 were obtained (not shown). The magnetostriction constant was λ〓0.6×10 ^-6 .

Comparative Example 1 A composition of Fe ₄ . ₇ Co ₇₀ . ₃ Ni ₄ Si ₉ B ₁₂ was measured. The magnetostriction constant was λ〓−1.0×10 ⁻⁶ . As a result of the measurement, in this sample, the shape of the polished surface and the coercive force varied depending on the location, and a hysteresis loop was observed that showed no specific dependence on the polishing direction (not shown). This is different from the above embodiment,
This shows that the composition of this example has almost no polishing effect.

Comparative Example 2 For a composition of Fe ₃ Co ₇₇ Si ₄ B ₁₆ , the Kerr hysteresis loops when an excitation field is applied parallel to and perpendicular to the polishing direction are shown in FIGS. 6 and 7, respectively. The magnetostriction constant λ = −1.4×10 ^-6 .

In this example, as shown in FIGS. 6 and 7, when the measurement magnetic field is in the same direction as the polishing direction,
A poorly squared loop similar to the one in the figure is obtained, while
A loop with good squareness was observed when the magnetic field was perpendicular to the polishing direction. This means that in the composition material of this example, magnetic anisotropy occurs such that the polishing direction is the axis of hard magnetization (that is, the direction perpendicular to it is the axis of easy magnetization), contrary to Examples 1 to 3. It shows what you did.

Comparative Example 3 A composition of Co ₇₅ Mo ₃ Si ₈ B ₁₄ was measured. The magnetostriction constant was λ〓−2.5×10 ⁻⁶ . As a result of the measurement, a loop similar to that of Comparative Example 2 was observed in this example as well. That is, when the measuring magnetic field is perpendicular to the polishing direction, a loop with extremely good squareness is obtained (not shown), and when the magnetic field is in the same direction as the polishing direction, a loop with extremely poor squareness as shown in Fig. 8 is obtained. A loop was observed. Therefore, it can be seen that magnetic anisotropy with an axis of hard magnetization in the polishing direction (the axis of easy magnetization is perpendicular to the direction) was generated in the composition material of this example due to polishing.

As can be seen from the examples and comparative examples described above, in materials whose magnetostriction constant λ is relatively small (2.2×10 ^-6 or less) positive or almost zero, magnetic anisotropy occurs in the polishing direction by polishing. However, in materials where λ is negative, magnetization occurs perpendicularly to the polishing direction, making it difficult to magnetize in the tape sliding direction.

In actual use, the polishing of the amorphous alloy sample in the above example involves collecting head chips from an amorphous ribbon-shaped alloy material, laminating them, etc. to form a magnetic head, and when the tape is slid, the head chips It is thought that the effect is the same as that of Therefore, in materials with a positive magnetostriction constant λ as in Examples 1 to 3 above, it is expected that sliding of the tape will produce magnetic anisotropy with an axis of easy magnetization in the direction of the gap of the head. Ru. The occurrence of magnetic anisotropy in the direction of the magnetic path length (head chip or head) near the head gap is caused by λ
When ≠0, head performance deterioration occurs near the gap of the magnetic head due to external stress due to processing, adhesion, resin molding, etc. during head fabrication, and internal stress of the material itself coupled with this λ. It acts in the direction of canceling (improving) the complex directional magnetic anisotropy that leads to. Note that such a canceling effect is greater as the depth of the head or head chip becomes shorter.

Example 4 A test piece similar to Example ₂ having _a composition _of Fe ₄ . ₇ Co ₇₀ . A loop was observed. The etching speed was approximately 0.5 μm/min, and the etching thickness was determined using a separately prepared directionally polished test piece (approximately 7 cm in length).
Two methods, (i) weight change and (ii) thickness measurement at specific locations, were used in combination in some cases. When the etching thickness was several micrometers, the measurement and evaluation results of methods (i) and (ii) agreed well.

Etching thickness: approx. 0.5μm, approx. 1μm, approx. 1.5μm
To summarize the measurement results of the hysteresis loop as the etching thickness increased from about 2 μm, about 3 μm, about 4 μm, to about 6 μm, it was found that when the etching thickness was 1.5 μm, the characteristics of the hysteresis loop due to polishing described in Example 2 did not disappear. , disappeared when the etching thickness was 1.5 μm. An example of the hysteresis loop of a test piece after etching of approximately 1.5 μm or more is shown in FIG. 9, and a hysteresis loop of the same test piece at another location is shown in FIG. 10, respectively. This figure 9 and 1
As is clear from Figure 0, the coercive force is generally considerably reduced, and the squareness ratio is also quite different compared to Figures 3 and 4. Moreover, the shape of the loop varies depending on the location of the specimen. It's different.

Example 5, Comparative Example 5 The same measurements as in Example 4 were made for the compositions Fe ₇ Co ₇₃ Si ₄ B ₁₆ and Fe ₃ Co ₇₇ Si ₄ B ₁₆ , but the relationship between etching thickness and hysteresis loop was Again, the same results as in Example 4 were obtained.

[Brief explanation of the drawing]

Figure 1 is a graph showing the Kerr hysteresis loop when an excitation magnetic field is applied parallel to the polishing direction for an amorphous alloy with the composition Fe ₇ Co ₇₃ Si ₄ B ₁₆ , and Figure 2 is a graph of the sample shown in Figure 1. Figure 3 is a graph similar to Figure 1 when an excitation field is applied perpendicular to the _polishing direction, and Figure ₃ is _a graph for the composition Fe ₄ . ₇ Co ₇₀ . A graph similar to Figure 1 when a field is applied, Figure 4 is for the sample in Figure 3,
A graph similar to Fig. 1 when an excitation field is applied perpendicular to the polishing direction; Fig. 5 is a graph similar to Fig. 1 when the polishing direction is random for the same sample as Fig. 3; Figure 6 is a graph similar to Figure 1 for the composition Fe ₃ Co ₇₇ Si ₄ B ₁₆ when an excitation field is applied parallel to the polishing direction, and Figure 7 is a graph for the sample in Figure 6, but in the polishing direction. Figure 8 is a graph similar to Figure 1 when an excitation field is applied at right angles to
A graph similar to Fig. 1 is obtained for the composition Co ₇₅ Mo ₃ Si ₈ B ₁₄ when an excitation field is applied parallel to the polishing direction, and Fig. 9 is a graph obtained by etching the surface of a sample similar to Fig. 3. FIG. 10 is a graph showing the Kerr hysteresis loop at another location in the sample of FIG. 9.

Claims (1)

[Claims] 1. A magnetic head consisting of core halves made of an amorphous magnetic alloy having a positive magnetostriction constant of 2.2×10 ^-6 or less and butted against each other via a non-magnetic gap.