JP2798315B2 - Composite magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite magnetic head, and more particularly, to a composite magnetic head formed by abutting magnetic core halves each having a soft magnetic thin film formed on a core made of an oxide magnetic material.

[0002]

2. Description of the Related Art Recently, a video tape recorder (VTR), a hard disk drive (HDD) or a floppy disk drive (FD)
In the field of magnetic recording such as D), recording signals have been increased in density, and therefore, a hard magnetic material having a high coercive force and a high residual magnetic flux density has been used as a magnetic material of a magnetic recording medium. Accordingly, a soft magnetic material having a higher saturation magnetic flux density and a higher magnetic permeability than ever before is also required for a soft magnetic material used for a magnetic head for writing a magnetic recording signal on the magnetic recording medium.

For this reason, a thin film made of a metal magnetic material having a high saturation magnetic flux density is deposited on a core block made of an oxide magnetic material such as ferrite, instead of the ferrite magnetic head having a low saturation magnetic flux density used conventionally. Composite magnetic heads having both a high saturation magnetic flux density and a high magnetic permeability having a magnetic core of the type have been used.

However, this metal-in-gap (MI
G) In the case of a composite magnetic head, which is also called a head, at the interface between the ferrite core and the thin film made of a metal soft magnetic material, a high temperature such as a heat treatment for crystallization of the soft magnetic film and a glass fusion At the time of heating, a reaction layer (or diffusion layer) is formed, and in this reaction layer, the magnetic characteristics as a soft magnetic material are significantly reduced. Therefore, this reaction layer forms a pseudo magnetic gap apart from a regular magnetic gap. .

When the pseudo magnetic gap is formed substantially parallel to the regular magnetic gap, and when the composite magnetic head is used as a reproducing magnetic head, the pseudo gap degrades the quality of a reproduced signal. . That is, the reproduced signal is a signal having a frequency characteristic in which peaks and valleys appear alternately as shown in FIG. 5 based on interference with the pseudo signal generated from the pseudo magnetic gap. The magnitude of this undulation (beat) is expressed as the ratio (dB) of the magnitude of the output signal at the peak and the valley in the frequency characteristic of FIG. Since the composite magnetic head having such a reproduction signal output is not practical for magnetic recording reproduction, the existence of the pseudo gap is a serious problem.

Japanese Patent Application Laid-Open No. 1-100714 discloses that in order to solve the above-mentioned problem, the thickness of a reaction prevention layer containing an oxide such as Si, Ti, Cr, or Al at the interface between both magnetic materials is reduced to 20 Å or less.
A composite magnetic head with 200 Å is disclosed.

[0007]

However, it is theoretically known that the magnitude of the undulation in the pseudo gap is a function of the ratio of the thickness of the pseudo gap to the gap length of the regular magnetic gap (IEEE papers). , 0018-964
/84/090-872S01.00 C 198
4) Therefore, the thickness of the reaction preventing layer of the above publication which acts as a pseudo gap also needs to be determined from the relationship with the gap length of the regular magnetic gap. There is no mention of this point in determining the thickness of the prevention layer.

According to the present invention, in consideration of the problem of the undulation of the pseudo gap, the thickness of the reaction preventing layer of the composite magnetic head is considered from a different viewpoint from the above-mentioned IEEE paper, so that the undulation signal can be suppressed to a certain level or less. An object of the present invention is to provide a composite magnetic head that can obtain a good reproduction signal by providing a reaction prevention layer that can be used.

[0009]

The object of the present invention is to provide an acid
A reaction prevention layer on a core block composed of
A pair of magnetic core halves with soft magnetic thin film
To form a magnetic gap between the tips of the thin films
In the composite magnetic head that is aligned with the magnetic recording medium, the magnetic gap is the length of the magnetic recording medium in the traveling direction.
A is the gap length, and the gap depth is perpendicular to the surface of the magnetic recording medium.
C(C ≦ 14 × 10 ^-6 m), Magnetic recording media
The width of the gap in the width direction is d, and the thickness of the reaction prevention layer is
Equation bcd / a ≦ 0.2 × 10^-10m²  Characterized by having the dimensions specified in
Achieved by the head.

The preferred ranges of each of b, c and d are as follows. b ≧ 2 × 10 ⁻⁹ m (20 angstroms) c ≦ 5 × 10 ⁻⁶ m d ≦ 10 × 10 ⁻⁶ m Since the reaction preventing layer also has the function of a pseudo gap, the smaller the thickness b, the better. At 25 to 30 angstroms, the effect of preventing the reaction is small, and at less than 20 angstroms, the effect of preventing the reaction is often lost.

As a soft magnetic thin film, Fe _p Zr _q N
_r (where p, q, and r each represent atomic%), and the composition thereof is in the range of 0 <q ≦ 200 0 <r ≦ 22 (provided that q ≦ 7.5 and r ≦ 5),
And those having magnetic properties equivalent to these can be used. As a material having the same magnetic characteristics as the soft magnetic thin film, Fe in the soft magnetic thin film is formed by one or more of Co, Ni, Ru and the like, for example, three of Fe.
It may be replaced up to about 0 atomic%. Also, Z
r or a part thereof may be replaced with another element.

That is, a preferred soft magnetic thin film is Fe _pm M _m
B _q N _r (where p, q, r, and m each represent atomic%;
Is Co, Ru, Cr, V, Ni, Mn, Pd, Ir, P
t represents at least one kind, and B represents Zr, Hf, T
represents at least one of i, Nb, Ta, Mo, and W. And the composition range is 0 ≦ m / p <0.30 <q ≦ 200 <r ≦ 22 (excluding q ≦ 7.5 and r ≦ 5). It is a soft magnetic thin film.

The present invention is based on the following findings . Magnetoresistive regular gap a r _m in a composite magnetic head having a reaction preventing layer, the magnetoresistance of the reaction preventing layer r _p (pseudo gap), if the magnetic resistance of the other core portion to r _c, the composite magnetic head Then, the respective signal regeneration efficiencies η _m and η _p in the regular gap and the pseudo gap are

[0014]

(Equation 1)

(Equation 2) It is expressed as Swell B

[0015]

(Equation 3) Therefore, the equation (3) is replaced by the equations (1) and (2).
Substituting

[0016]

(Equation 4) Is obtained.

[0017] In the pseudo-gap, since the gap length is very small compared to the gap length of the gap of the normal, the magnetoresistance is very small compared to the magnetic resistance of the normal gap, r _p << r _m is established Therefore, the above equation (4) becomes

[0018]

(Equation 5) Next, waviness B see this equation (5) is that determined by the ratio of the magnetic resistance r _p of the magnetic resistance r _m and the pseudo gap regular gap.

The magnetoresistive r _m of the gap legitimate, the gap length a, gap depth c, a gap width (track width)
d, and this by the magnetic gap portion of the mu _o is expressed as _{r m = μ o a / cd} , whereas the magnetoresistive r _p of the pseudo gap, r _p <
<It believed represented as approximately by the thickness b of the reaction preventing layer to consider the _{r m r p = kb (k} = constant). From these relationships, it can be obtained that the magnitude of the undulation B is proportional to bcd / a.

In the present invention, the factor which determines the magnitude of the undulation generated in the reproduction signal of the composite magnetic head having the reaction preventing layer as described above is bcd / a according to the respective dimensions a to d of the composite magnetic head. In the composite magnetic head having a reaction preventing layer acting as a pseudo gap, the value of bcd / a for making the swell in the reproduced signal equal to or less than a certain value (1 dB or less) is determined by experiment, and the reaction is determined. The thickness b of the prevention layer is determined.

The magnetic head used in this experiment was a composite magnetic head manufactured by the composition and manufacturing method disclosed in Japanese Patent Application No. 1-204586, which was a prior application filed by the applicant. MnZn single crystal ferrite, SiO ₂ as reaction prevention layer, Fe _80.9 Zr as soft magnetic film
_6.5 N _12.6 (at%), temperature treatment at 550 ° C.

[0022]

[Experiment 1] FIG. 2 is a graph showing the measurement results in Experiment 1, showing the undulation component in the reproduced signal as a function of bcd / a. The horizontal axis is bcd / a,
The ordinate represents the undulation in dB. In this experiment, the gap length a was a = 0.2 μm, and the thickness b of the reaction prevention layer was b =
0.01 μm (100 Å), track width d = d =
It was fixed at 25 μm, and c was changed from 30 μm to 0.

In FIG. 2, 0.2 × 10 ⁻¹⁰ m ² was obtained as the bcd / a value of the composite magnetic head that gives a undulation of 1 dB or less, which is a practically sufficient value for the quality of the reproduced signal.

That is, bcd / a having a larger value
In this range, even if the thickness b of the reaction prevention layer is 100 Å, which was conventionally considered to be a sufficiently small value, a reproduced signal including a large undulation of 1 dB or more is output, and A composite magnetic head that does not withstand use above. Thus, the value of bcd / a is 0.2
A reproduction signal including a swell signal of 1 dB or less, which is a practically sufficient value, can be obtained only by a composite magnetic head having a value in the range of × 10 ⁻¹⁰ m ² or less.

For example, when only the track width d is d = 10 μm while the gap length a is a = 0.2 μm and the gap depth c is c = 20 μm (reference example) , the thickness b of the reaction preventing layer is b .Ltoreq.200 angstroms. Therefore, by increasing the thickness b of the reaction preventing layer to this value, the magnitude of the undulation is suppressed to 1 dB or less, and a practically sufficient reproduced signal can be obtained.

With the gap length a set to a = 0.2 μm and the track width d set to d = 25 μm, only c = c
When the thickness is 5 μm, the thickness b of the reaction prevention layer is b ≦ 320.
Angstrom, and the thickness b of the reaction preventing layer can be increased to this value. The value of the gap depth c is required to be about 10 μm as a lower limit for a magnetic head sliding on a medium such as a floppy disk drive (FDD), but for a non-sliding magnetic head such as a hard disk drive (HDD). The thickness can be reduced to 5 μm or less. In this case, even if the thickness of the reaction preventing layer is increased to the above value, the reliability of the reproduced signal is sufficiently ensured.

In order to confirm the results of the above experiment 1, the following experiment 2 was performed on the composite magnetic head manufactured with the same composition and the same manufacturing method, while changing the gap width d.

[0028]

[Experiment 2] As a sample of the composite magnetic head, the group of sample 1 has dimensions of a = 0.2 μm, b = 100 Å, c = 25 μm, d = 15 μm, and the group of sample 2 has a = 0.2 μm. b = 100 angstroms, c = 25 μm, d = 25 μm, 20
The undulations contained in the reproduced signals of these composite magnetic heads (reference examples) were measured individually, and the average value and variance of the obtained undulations were plotted as shown in FIG.

As shown in FIG. 3, in the composite magnetic head of group 1 having a bcd / a of 0.19, a good reproduced signal having an undulation of substantially 1 dB or less was obtained, but the bcd / a was 0.31.
According to the composite magnetic head of Group 2, only a reproduced signal containing a large undulation exceeding 1 dB was obtained.

Even when the value of d was changed as described above, it was confirmed that a good composite magnetic head with less waviness in the reproduced signal could be obtained by the composite magnetic head of bcd / a ≦ 0.2. Could be reinforced.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The above-mentioned Japanese Patent Application No.
The materials and methods of manufacture disclosed in US Pat. No. 204586 can be used.

For example, ferrite is selected as the oxide magnetic material. Ferrite generally has a composition of MO.Fe ₂ O ₃ . Here, M is a divalent metal ion, for example, ^{Mn 2 +, Fe 2+, Co} 2+, Ni 2+, Cu 2+, is a Zn ²⁺ or the like, M
May be two or more divalent metal ions. As such ferrite, for example, there is MnZn single crystal ferrite. SiO ₂ is used as the reaction preventing layer, and is formed on the core block made of ferrite by a vapor deposition method such as sputtering.

[0033] As the soft magnetic thin film, Fe _pm M _m B _q N
_r (where p, q, r, and m each represent atomic%, M is C
o, Ru, Cr, V, Ni, Mn, Pd, Ir, Pt; and B represents Zr, Hf, Ti,
It represents at least one of Nb, Ta, Mo, and W. And the composition range is 0 ≦ m / p <0.30 <q ≦ 200 <r ≦ 22 (excluding q ≦ 7.5 and r ≦ 5). A soft magnetic thin film can be used.

The soft magnetic thin film has the following effects when a part of Fe is replaced with the specific amount of element M.

The magnetostriction can be changed in the positive direction according to the content of the element M, or can be accurately adjusted to a value close to 0 (absolute value). The saturation magnetic flux density Bs can be further increased (particularly when M is Co). Even when the magnetostriction is small, an anisotropic magnetic field can be applied to several Oe (at least up to about 2 Oe), and a high magnetic permeability can be obtained even when used at a high frequency (especially when M is Co). Corrosion resistance can be further improved (in particular, M is Cr, Co, Ni, Pd, I
r, at least one of Pt and Ru). Since the electrical resistivity can be increased, eddy current loss can be reduced, and high magnetic permeability can be obtained even when used at high frequencies (particularly when M is at least one of V, Cr, and Mn).

The soft magnetic thin film in the case where m = 0 and B = Zr in the above composition formula can be used as a preferable one. Therefore, this case will be described below. Zr as a whole or a part of Zr
It is considered that even when the above B other than r is used, almost the same characteristics are exhibited.

The soft magnetic thin film is Fe _p Zr _q N _r (where p,
q and r each represent atomic%. An alloy represented by the following composition formula is used, and its composition is in the range of 0 <q ≦ 200 0 <r ≦ 22 (excluding q ≦ 7.5 and r ≦ 5).

Preferably, the composition range is in the range of 69 ≦ p ≦ 932 ≦ q ≦ 15 5.5 ≦ r ≦ 22.

The above composition range is shown in FIG. 6 by points Q, K, L, U and M. More preferably, the composition range is P (91, 2, 7) Q (92.5, 2, 5.5) R (87, 7.5, 5.5) in the three-component composition coordinate system (Fe, Zr, N). S (73, 12, 15) T (69, 12, 19) U (69, 9, 22) V (76, 5, 19) A range surrounded by a line connecting seven points. This composition range is shown in FIG. 6 by points P, Q, R, S, T, U, and V.

More preferably, the crystal grain size is 300 Å or less, and the soft magnetic film has uniaxial anisotropy.

When the composition range of the soft magnetic film is in the range of 0 <q ≦ 20 and 0 <r ≦ 22 (excluding q ≦ 7.5 and r ≦ 5), it is preferable that q ≧ 0.5 and r ≦ 5. Let r ≧ 0.5. This is because when q <0.5 or r <0.5, the effect due to its presence may not be clear.

When Zr of the soft magnetic layer exceeds 20 at% or N exceeds 22 at%, good soft magnetism cannot be obtained.

When the composition range of the soft magnetic layer is 69 ≦ p ≦ 93, 2 ≦ q ≦ 15 and 5.5 ≦ r ≦ 22, better soft magnetism is exhibited.

More preferably, in the three-component ternary composition coordinate system (Fe, Zr, N), the specific points P, Q, R, S, T, U, and V are defined. It is the range enclosed by the connecting line segments. Since the coercive force is particularly small in this composition range, it is suitable as a core material of a magnetic head. The most preferable range is a composition range in which the coercive force is 1.5 Oe or less (furthermore, 1 Oe or less).

[0045] Further preferred compositional range of the soft magnetic layer is in the range represented by _{Fe s (Zr t N 1-} t) 100-s 77 ≦ s ≦ 88 0.3 ≦ t ≦ 0.38. This composition range is defined as points W, X, Y,
This is shown in FIG. The coordinates of these points W, X, Y, Z are approximately as follows.

W (88, 3.6, 8.4) X (88, 4.56, 7.44) Y (77, 8.74, 14.26) Z (77, 6.9, 16.1) That is, in this range, 77 to 88 atomic% of Fe is contained, Further, the ratio r / q of the content ratio q (atomic%) of Zr and the content ratio r (atomic%) of N in the soft magnetic layer is approximately 1.63 to 2.33. The soft magnetic layer having this composition range has good soft magnetism (for example, coercive force Hc <5 Oe).

In the soft magnetic layer, Hf, Ti, Nb, Ta,
At least one of V, Mo, and W can replace a part of Zr (for example, 30 atomic% of Zr constituting the soft magnetic layer). Further, Fe in the soft magnetic film can be replaced by one or more of Co, Ni and Ru, for example, up to about 30 atomic% of Fe.

[0048] to produce an alloy target of a composition of the soft magnetic thin film production examples and characteristics _{Fe 100-y Zr y (y} = 5.0,10.0,15.0), each containing 2.5 to 12.5 mol% of nitrogen, the nitrogen-containing argon gas atmosphere Medium, gas pressure 0.6P
a, High frequency sputtering was performed under the conditions of a power of 200 W to obtain amorphous alloy thin films of various compositions. Each of these thin films was heat-treated in a magnetic field to obtain a soft magnetic thin film, and their saturation magnetic flux density Bs and coercive force Hc were measured. Bs and Hc are measured using an AC BH tracer (applied magnetic field: 50 Hz, 25 Oe, but Hc
For> 25, it is based on 90 Oe). As the substrate, a crystallized glass substrate (PEG3130C HOYA) and a single crystal sapphire substrate were used. The thickness of each film was about 0.6 μm.

Table 1 shows the results. Hc is indicated by a value in the easy axis direction. Some of the soft magnetic thin films were measured for the magnetic permeability μm and the magnetostriction at 5 MHz. As for the magnetostriction, the positive / negative judgment of the magnetostriction was made from the change of the BH characteristic when a stress was applied to the film. The results are also shown in Table 1.

FIG. 7 shows the relationship between the composition of the soft magnetic thin film and the coercive force Hc and the positive / negative judgment of magnetostriction (in the case of heat treatment at 550 ° C. using a crystallized glass substrate). . Furthermore, in the Fe-Zr alloy target
FIG. 8 shows the relationship between the soft magnetic thin film production conditions of the Fe content and the N ₂ content in the sputtering gas, the coercive force Hc, and the saturation magnetostriction λs (when heat-treated at 550 ° C. using a crystallized glass substrate). .

In the production example of the soft magnetic thin film, Fe _80.9 Zr _6.5 N
_For the composition of _12.6 , unheated (as depo) thin film, 250,
FIG. 9 shows the results of the X-ray diffraction of the thin film heat-treated at 350, 450 or 550 ° C., and Table 2 shows the results of the measurement of the electric resistivity. According to FIG. 9, it was found that the crystal grain size of the thin film subjected to the heat treatment at 550 ° C. was about 130 Å from the half width. It was found that the as depo thin film and the thin film heat-treated at 250 ° C. were amorphous, the thin film heat-treated at 350 ° C. and 450 ° C. consisted of microcrystals, and the thin film heat-treated at 550 ° C. consisted of further grown microcrystals. These microcrystals are considered to contribute to the soft magnetism of the thin film, and the generation of such microcrystals is
And Zr. According to Table 2, by increasing the heat treatment temperature, the resistivity of this thin film decreases, but even when the temperature is increased to 550 ° C., the value is much higher than that of pure iron, permalloy, etc. It is almost the same value as Fe-Si alloy and Sendust. Therefore, when used as a core of a magnetic head,
Advantageously, the eddy current loss is small.

Further, the Vickers hardness of the thin film having the composition of Fe _80.9 Zr _6.5 N _12.6 was measured. As a result, Hv = 1000 (kg / kg)
mm ² , weight 10 g). This value is much higher than Sendust and Co-based amorphous alloys (Hv = 500-650), which have been used as magnetic head materials.
The abrasion resistance can be sufficiently increased as compared with the conventional case.

FIG. 10 shows BH curves of several thin films produced in the same manner as in the production example of the soft magnetic thin film, using an AC BH tracer.

The sample shown in FIG.
Heat treatment is performed at 550 ° C. for 60 minutes in a 10 Torr N ₂ atmosphere in a magnetic field. As is apparent from this figure, a clear in-plane uniaxial anisotropy is induced in the thin film by the heat treatment in the magnetic field. Therefore, by setting the hard axis direction of this thin film as the magnetization direction, the magnetic permeability at a frequency higher than 1 MHz can be made sufficiently high, which is also advantageous as a magnetic head material. Further, since the anisotropic magnetic field Hk varies from 3 to 18 Oe depending on the composition, a material can be selected according to a target magnitude of the magnetic permeability and a frequency range to be used. For example, when it is desired to obtain a high magnetic permeability at 10 MHz or less, a composition having Hk = 3 to 5 Oe is used. In order to prevent the magnetic permeability from deteriorating even at a higher frequency, a composition having a higher Hk can be used. .

FIG. 11 shows that in the production example of the soft magnetic thin film,
The results of the MH curve (IH curve) of a thin film having a composition of _80.9 Zr _6.5 N _12.6 measured using a VSM are shown. In the figure
(a) is a thin film immediately after film formation (as depo), (b) is 550 ° C
3 shows an MH curve (IH curve) of the thin film after the heat treatment. (The demagnetizing field correction was not performed. However, the sample shape was φ5 mm × t0.63 μm.) The coercive force measured by using a VSM was at least one digit smaller than the value obtained with an AC BH tracer. ) And about 50 mOe. This value is almost equivalent to Sendust and Co-based amorphous alloys, indicating that the soft magnetic properties are excellent. Further, 4πMs = 14.5KG is obtained from (b), which is sufficiently higher than Sendust or a Co-based amorphous alloy, and is advantageous as a magnetic head material for recording on a medium having a high coercive force.

The 4πMs of the thin film before the heat treatment is 13.0 KG, which is slightly lower than that after the heat treatment. Further, it has perpendicular anisotropy (Hk is about 400 Oe), has high Hc, and has poor soft magnetic properties.

In the above production example of the soft magnetic thin film, Fe _80.9 Zr _6.5 N
_The corrosion resistance of the thin film having the composition of _12.6 was evaluated from the change in the surface state after being immersed in tap water for about one week. As a result, the surface state of this sample did not change at all with a mirror surface. For comparison, a similar experiment was performed on a Co _88.4 Nb _8.0 Zr _3.6 amorphous alloy film and an Fe—Si alloy (magnetic steel sheet). As a result, the Co-Nb-Zr alloy did not change at all, but rust occurred on the entire surface of the Fe-Si alloy. From the above, it has been found that the soft magnetic thin film used as the soft magnetic layer of the composite magnetic head in this preferred embodiment has excellent corrosion resistance.

Table 3 shows the analytical composition and values of the saturation magnetostriction, Bs, Hk, Hc, and ρ of an example of the soft magnetic thin film in which a part of Fe was replaced by M. These soft magnetic thin film is loaded _{Fe-M-Zr 10 (M} = Cr or Co) target, or V, a small piece of Mn or Ni
Using a target of Fe ₉₀ Zr ₁₀ , high-frequency sputtering is performed in a 10% N ₂ -Ar atmosphere to form an Fe-M-Zr-N amorphous thin film (M = V, Cr, Mn, Co or Ni). , These are 550
It was obtained by heat treatment in a magnetic field at 4 ° C. for 4 hours.

Next, a soft magnetic thin film having a composition outside the composition range of the soft magnetic layer of the composite magnetic head according to the preferred embodiment will be described.

An amorphous alloy film of Fe _91.2 Zr _3.9 N _4.9 was formed and heat-treated at 350 ° C. and 550 ° C. for 1 hour in a magnetic field of 1 kOe. The BH curves of the amorphous alloy film (as depo), the film heat-treated at 350 ° C., and the film heat-treated at 550 ° C. by the AC BH tracer are shown in FIGS. 11A to 11C, respectively. The unheated amorphous alloy film (as depo) does not have soft magnetism (a). The film heat-treated at 350 ° C. shows uniaxial anisotropy (b). However, the film heat-treated at 550 ° C. has poor properties (c).

At the time of manufacturing the magnetic head, welding (glass bonding) with molten glass is sometimes performed, and is usually performed by heating to about 550 ° C. When a film having the above composition range is used, good soft magnetism is not exhibited in the finally obtained magnetic head due to the heating during the glass bonding. That is, in the case of the above composition range, only a thermally unstable soft magnetic thin film can be obtained.

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

[Table 3]

An amorphous layer, which is a soft magnetic thin film having the above composition, formed on a core block made of an oxide magnetic material via a reaction preventing layer is obtained.
And a part or all of the amorphous layer is crystallized. Even after such heat treatment, no reaction layer is formed between the ferrite core and the soft magnetic film due to the interposition of the reaction prevention layer. Preferably, the amorphous layer is formed by heat treatment in a magnetic field to induce uniaxial magnetic anisotropy to crystallize part or all of the amorphous layer. In this case, the thickness of the reaction preventing layer is determined as follows.

For example, the gap length a of the magnetic gap of the composite magnetic head to be manufactured is 0.2 μm and the gap depth c is 10 μm.
m and track width are selected as 25 μm respectively,
The thickness of the reaction-preventing layer b can be obtained from the formula: bcd / a ≦ 0.2 × 10 ⁻¹⁰ m ² , b ≦ 160 Å. In order to sufficiently prevent the reaction between the oxide magnetic material core block and the metal soft magnetic film by the reaction prevention layer made of SiO ₂ , the thickness b
Considering that it is preferable to form as thick as possible and economical dimensional control, this value is, for example, b
= 100 angstroms. Alternatively, if it is desired to form a film in a short time, for example, b = 50 angstroms is selected.

[0067]

The dimensions a and c of the magnetic gap having a value of bcd / a in the range of 0.2 × 10 ⁻¹⁰ m ² or less.
(C ≦ 14 × 10 ⁻⁶ m) , d and thickness b of the reaction preventing layer
In a composite magnetic head having a sine wave, when the signal recorded on the magnetic recording medium is reproduced, the swell signal in the reproduced signal is one.
dB or less, which is a sufficient value for the performance of the electromagnetic conversion element during reproduction.

Further, for example, in the case of a composite magnetic head for reproducing data from a high-density magnetic recording medium having an extremely small track width d, or a non-sliding magnetic head for an HDD having an extremely small gap depth c. In the case of the composite magnetic head of the above, the thickness b of the reaction preventing layer can be made extremely large by determining according to the above equation, and the reaction preventing layer having a sufficient thickness to prevent the reaction between the oxide magnetic material and the soft magnetic film. It is possible to provide a composite magnetic head that forms a prevention layer and obtains a reproduced signal of practically sufficient quality.

[0069]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The construction of a composite magnetic head according to the present invention will be described with reference to FIG. 1 which is an enlarged view of the tip of a magnetic core of a composite magnetic head for recording and reproduction according to the embodiment.

In FIG. 1, the magnetic core of this embodiment has a structure in which magnetic core halves 10, 10 'manufactured separately are fused and joined by filling portions 5, 5' made of a glass material.

The ferrite cores 1 and 1 ′, which are magnetic materials constituting the majority of the magnetic core halves 10 and 10 ′, abut the two magnetic core halves 10 and 10 ′ each having a magnetic gap G at the tip. On the surface side, there are opposing surfaces 11, 11 '
It has retreating surfaces 12, 12 'formed to extend from 11, 11' and retreating in the direction opposite to the abutting surface.

The opposing surfaces 11, 11 'and the receding surfaces 12, 1
A reaction prevention layer 2, 2 ′ made of SiO ₂ and having a thickness b (b = 50 angstroms) is formed over the entire surface of the magnetic core half 2 ′ on the abutting surface side. 'On the surface of Fe _80.9 Zr _6.5 N _12.6
Are formed by the thin film method. The metal soft magnetic films 3, 3 'together with the core blocks 1, 1' made of respective oxide magnetic materials constitute a part of the magnetic core of the magnetic core halves 10, 10 'of the composite magnetic head. When assembling the magnetic core, both magnetic core halves 1
0, 10 'are arranged so that the metal soft magnetic films 3, 3' on the surface are opposed to each other, and thereafter formed on the receding surfaces 12, 12 'of the ferrite core block.
It is fused joined by 'glass materials 5, 5 filled in the' recess 32, 32 formed by the. A winding groove M is formed in a part of the joint area between the two magnetic core halves 10, 10 'as a groove penetrating the inside of the manufactured magnetic core.

The opposing surfaces 11, 1 of the ferrite cores 1, 1 '
A magnetic gap G made of a glass material is formed at the tip of the part where the two soft metal magnetic films 3 and 3 'disposed on the 1' soil face each other in a part facing each other. The gap length a, which is the dimension of the magnetic gap G in the traveling direction of the magnetic recording medium disposed to face the composite magnetic head, is 0.2 μm, and the track width d, which is the width of the magnetic gap G in the direction perpendicular thereto, is 25 μm. The gap depth c, which is the depth of the magnetic gap perpendicular to the recording medium surface, is selected to be 5 μm.

FIG. 4 shows the frequency characteristics of the reproduced signal output from the composite magnetic head of this embodiment. As shown in the figure, the undulation component in the reproduced signal is practically negligible and a reproduced signal of good quality is obtained.

The recording / reproducing composite magnetic head of the above embodiment
When manufacturing the magnetic core of the magnetic gap G
Gap length a, gap depth c of the magnetic gap(C ≦ 1
4 × 10 ^-6 m)And the track width d is
Recording wavelength in a magnetic recording medium arranged opposite to
Determined by considering the service life due to track width and wear
And the thickness b of the reaction preventing layer is expressed by the following formula: bcd / a ≦ 0.2 × 10^-10m²  The size is selected to satisfy Reaction prevention as described above
The thickness b of the stop layer is determined by the gap depth c and the track width d.
For a composite magnetic head of a very small type, these c and c
Can be selected largely according to the values of d and d.
The reaction preventing layer having the selected thickness b is made of an oxide magnetic material.
Block composed of metal and thin film composed of metallic soft magnetic material
Can sufficiently prevent the reaction between
A sufficient reaction prevention layer can be obtained.

[0076]

According to the present invention, a recording / reproducing apparatus having a reaction preventing layer according to the present invention.
In the configuration of the raw composite magnetic head, the composite magnetic head
Is the gap length of the magnetic gap, and the gap depth is c.
(C ≦ 14 × 10 ^-6 m)And the gap width is d and
Bcd / a ≦ 0.2 × 10 where b is the thickness of the anti-static layer^-10m²  By having each dimension defined as
The thickness of the stop layer corresponds to each dimension of the magnetic gap.
Of the magnetic gap
For composite magnetic heads for various applications with different dimensions
The magnitude of the swell signal included in the playback signal
It can be easily held down to 1dB or less, a value that does not matter.
To provide a composite magnetic head with high playback quality
I was able to.

Particularly, in the case of a composite magnetic head for reproducing a signal on a recording medium recorded at a high density and having a small track width,
Alternatively, in the case of a composite magnetic head in which the gap depth can be set small because a non-sliding access method is employed, such as a hard disk device, the value of the thickness b of the reaction prevention layer can be obtained without increasing the swell signal in the reproduction signal Can be made large, so that a reaction prevention layer having a thickness sufficient to prevent the reaction between the oxide magnetic material and the soft magnetic film can be formed, and despite the presence of the pseudo gap due to the large thickness of the reaction prevention layer. In addition, it was possible to provide a composite magnetic head in which the undulation signal included in the reproduction signal was small and the quality of the reproduction signal sufficient for practical use could be maintained.

[Brief description of the drawings]

FIG. 1 is a view of a magnetic core showing a structure of a composite magnetic head according to one embodiment of the present invention.

FIG. 2 is a graph showing measured values of the relationship between a value bcd / a determined by the dimensions of each part of the magnetic gap and the thickness of the reaction preventing layer and a swell signal, which were confirmed by Experiment 1 in the present invention.

FIG. 3 is a graph similar to FIG. 2 showing measurement data of Experiment 2.

FIG. 4 is a frequency characteristic of a reproduction signal of the composite magnetic head according to the embodiment of the present invention.

FIG. 5 is a graph showing general frequency characteristics of a reproduction signal of a conventional composite magnetic head.

FIG. 6 is a view showing a composition range of a soft magnetic layer of a composite magnetic head according to a preferred embodiment of the present invention.

FIG. 7 is a diagram showing a relationship between a composition of a soft magnetic thin film manufactured in a manufacturing example of a soft magnetic thin film and a coercive force Hc, and a positive / negative determination of magnetostriction.

FIG. 8 is a diagram showing the relationship between soft magnetic thin film manufacturing conditions and the coercive force Hc and saturation magnetostriction λs of the soft magnetic thin film manufactured thereby.

FIG. 9 is a diagram showing the results of X-ray diffraction measurement of thin films having different heat treatment conditions.

FIG. 10 is a diagram showing an AC BH curve of thin films having different compositions.

FIG. 11 is a diagram showing IH curves of a thin film before and after heat treatment obtained by VSM.

FIG. 12 is a view showing an AC BH curve of a soft magnetic thin film having a composition outside the composition range of the soft magnetic layer of the composite magnetic head according to the preferred embodiment of the present invention.

[Explanation of symbols]

 1, 1 ': Ferrite core half 2, 2': Reaction prevention layer 3, 3 ': Metal soft magnetic film 5, 5': Glass filled portion 10, 10 ': Magnetic core half G: Magnetic gap M: winding Wire groove

Continuation of front page (72) Inventor Kanji Nakanishi 798 Miyadai, Kaisei-cho, Ashigara-gun, Kanagawa Prefecture Fuji Photo Film Co., Ltd. (56) References JP-A-63-298806 (JP, A) JP-A-63-39106 (JP) , A) JP-A-2-208811 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G11B 5/23 G11B 5/187 G11B 5/127

Claims (5)

(57) [Claims] 1. A method according to claim 1, wherein the core block is made of an oxide magnetic material.
A pair of magnetic cores formed with a soft magnetic thin film via a reaction prevention layer
A magnetic gap is formed between the tips of the soft magnetic thin films.
A composite magnetic head
And the length of the magnetic gap in the direction of travel of the magnetic recording medium.
A is the gap length, and the gap depth is perpendicular to the surface of the magnetic recording medium.
C(C ≦ 14 × 10 ^-6 m), Magnetic recording media
The width of the gap in the width direction is d, and the thickness of the reaction prevention layer is
Equation bcd / a ≦ 0.2 × 10^-10m²  Characterized by having the dimensions specified in
head. 2. The composite magnetic head according to claim 1, wherein d ≦ 10 × 10 ⁻⁶ m. 3. The composite magnetic head according to claim 1, wherein c ≦ 5 × 10 ⁻⁶ m. 4. The composite magnetic head according to claim 1, wherein b ≧ 2 × 10 ⁻⁹ m. Wherein said soft magnetic thin _{film, Fe pm M m B q N} r ( where, p, q, r, m each represent atomic%, M is Co, R
u, Cr, V, Ni, Mn, Pd, Ir, or Pt, and B represents Zr, Hf, Ti, Nb,
It represents at least one of Ta, Mo, and W. And the composition range is 0 ≦ m / p <0.30 <q ≦ 200 0 <r ≦ 22 (excluding q ≦ 7.5 and r ≦ 5). 5. The composite magnetic head according to claim 1, wherein: