JPH08102006A - Magnetic head - Google Patents

Abstract

PURPOSE: To prevent the formation of a corrosive cell at the time of combination with ferrite and to improve corrosion resistance. CONSTITUTION: In a composite head consisting of an Fe-based magnetic film having high saturation magnetic flux density and ferrite, the concn. of Fe2 O3 in the ferrite is regulated to 55-65mol% and that of ZnO to 10-25mol%. The oxidation potential of the ferrite is lowered by the increased concn. of Fe2 O3 and the difference between the oxidation potential of the resultant ferrite and that of the magnetic film is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head for high density recording which is excellent in corrosion resistance and recording / reproducing characteristics, and a highly reliable magnetic disk device or VTR using this magnetic head.
The present invention relates to a magnetic recording device such as a device.

[0002]

2. Description of the Related Art In recent years, the progress of high-density magnetic recording has been remarkable, and the increase in recording density has led to the miniaturization and higher performance of devices. In order to further increase the recording density, a medium having a high coercive force is used, and a magnetic material having a high saturation magnetic flux density is required for the core material of the magnetic head in order to generate a sufficiently recordable magnetic field. . As a magnetic head using a magnetic material having such a high saturation magnetic flux density, a head having a magnetic core formed by forming a high saturation magnetic flux density magnetic film on a non-magnetic substrate is also used. Characteristic,
From the viewpoint of wear resistance and the like, a so-called MIG head in which a magnetic film having a high saturation magnetic flux density is formed near a gap of a magnetic core of high-permeability ferrite is widely used. In addition, a head configured such that the interface between the ferrite core and the magnetic film is not parallel to the gap is also used.

As a magnetic film having such a high saturation magnetic flux density, FeAl having a saturation magnetic flux density of about 1 T has hitherto been used.
Although Si-based alloy films have been used, as described in JP-A-3-20444 or JP-A-2-275605, in recent years, Fe has been the main component and Ti, Zr, Hf, Nb, and T have been used.
Magnetic films having a microcrystalline structure containing a transition metal such as a, Mo and W and a non-metal element such as C, N and B have been studied. These have a high saturation magnetic flux density of about 1.5 T, and have excellent soft magnetic characteristics such as low coercive force and high magnetic permeability.

[0004]

However, the above-mentioned high saturation magnetic flux density magnetic film containing Fe as a main component has a problem in corrosion resistance, and in the high humidity environment, dew condensation may occur on the magnetic film portion of the head, and chlorine ion may be generated. There was a problem that the magnetic film corrodes when placed in an environment containing This problem was particularly noticeable in the head in which ferrite and a high saturation magnetic flux density magnetic film were combined.

An object of the present invention is to improve the corrosion resistance of a magnetic head using a high saturation magnetic flux density magnetic film and to provide a magnetic head having excellent recording / reproducing characteristics and reliability.

[0006]

DISCLOSURE OF THE INVENTION As a result of intensive studies made by the present inventors in order to improve the corrosion resistance of a magnetic head using the above-mentioned high saturation magnetic flux density magnetic film, the corrosion resistance of the magnetic head is high saturation magnetic flux density magnetic film. It was found that not only the corrosion resistance, but also the properties of ferrite have a great influence. That is, ferrite has a high oxidation potential and is electrochemically noble, whereas a high saturation magnetic flux density magnetic film containing Fe as a main component has a low oxidation potential and is electrochemically base. Therefore, it is considered that, when both of them come into contact with each other and water is condensed, a corrosion battery is formed between the ferrite and the high saturation magnetic flux density magnetic film, and the high saturation magnetic flux density magnetic film is significantly corroded. Also, this corrosion is significantly accelerated in the presence of chloride ions in the environment.

In the present invention, in order to prevent the formation of such a corrosion battery and to improve the corrosion resistance, a method of lowering the oxidation potential of ferrite and reducing the potential difference from the oxidation potential of the high saturation magnetic flux density magnetic film as much as possible. Take Specifically, F
Ferrite having a concentration of e ₂ O ₃ of 55 mol% or more is used in combination with the high saturation magnetic flux density magnetic film. The specific configuration of the present invention is shown below.

(1) In a magnetic head in which a high saturation magnetic flux density magnetic film containing Fe as a main component is formed in at least a part of the vicinity of the gap of a magnetic core made of high permeability ferrite, Fe ₂ O ₃ Magnetic head having a concentration of 55 mol% or more and 65 mol% or less.

(2) In the magnetic head according to (1), the high magnetic permeability ferrite is MnZn ferrite.

(3) The magnetic head according to (1) or (2), wherein the concentration of ZnO is 10 mol% or more and 25 mol% or less.

(4) A magnetic head in which the concentration of ZnO is 15 mol% or more and 22 mol% or less in (1) to (3).

(5) The magnetic head according to (1) to (4), wherein the Fe ₂ O ₃ concentration is 60 mol% or less.

(6) A magnetic head according to any one of (1) to (5), wherein the high saturation magnetic flux density magnetic film is a magnetic film containing 50 at% or more of Fe.

(7) In the above (6), the high saturation magnetic flux density magnetic film contains Fe at 50 at% or more and C, N, B, Si,
One or more elements of Al and Ti are added.
A magnetic head containing 1 or more and 20 at% or less.

(8) In (7), the high saturation magnetic flux density magnetic film contains 50 at% or more of Fe, 1 at% or more and 20 at% or less of any one element of C, N, B and O, and Ti, A magnetic head containing 2 at% or more and 20 at% or less of any one or more of Zr, Hf, Nb, Mo and W.

(9) In (8), the high saturation magnetic flux density magnetic film is represented by the composition formula: Fe _a M _b T _c X _d Y _e R _f Z _g , where:
Element group M is one or more elements of Co and Ni, element group T
Is one or more of Ti, Zr, Hf, Nb, Ta, Mo, W, and the element group X is Ru, Rh, Os, Ir, Pd, P
One or more of t, Au, Ag and Cu, and the element group Y is C
One or more of r, V, Al and Si, the element group R is Y and one or more of the rare earth elements, and the element group Z is C, N, B,
One or more of O, b ≦ 40, 2 ≦ c ≦ 20,
0 ≦ d ≦ 15, 0 ≦ e ≦ 20, 0 ≦ f ≦ 10, 1 ≦ g ≦
A magnetic head having a composition of 20, a + b + c + d + e + f + g = 100 (where a, b, c, d, e, f, and g are at%).

(10) The magnetic head according to (6) to (9), wherein the high saturation magnetic flux density magnetic film has an average crystal grain size of 50 nm or less.

(11) The magnetic head according to (6) to (10), wherein the high saturation magnetic flux density magnetic film has an average crystal grain size of 20 nm or less.

(12) A magnetic head in which the high saturation magnetic flux density magnetic film having the above composition in (6) to (11) is laminated with a thin film having another composition as an intermediate layer.

(13) One or more magnetic heads described in (1) to (12) are used in a magnetic recording device which uses the magnetic head for recording, reproducing or erasing a signal on a recording medium. Magnetic recording device.

[0021]

In the magnetic head of the present invention, the F of ferrite is
By adjusting the concentration of e ₂ O ₃ to 55 mol% or more, Fe
The divalent concentration is increased, which lowers the oxidation potential of ferrite, and can reduce the difference in oxidation potential with the high saturation magnetic flux density magnetic film. If the concentration of Fe ₂ O ₃ exceeds 65 mol%, the magnetostriction constant of ferrite increases and the magnetic permeability decreases, so it must be 65 mol% or less. In order to suppress the decrease in magnetic permeability, it is more preferable that the concentration is 60 mol% or less.

If ZnO is less than 10 mol%, the magnetostriction constant also increases, so ZnO must be 10 mol% or more. To improve the magnetic permeability, the above Zn
It is preferable that the content of O is 15 mol% or more. Further, when ZnO exceeds 25 mol, the saturation magnetic flux density and the Curie temperature decrease remarkably. Therefore, it is necessary to set the content to 25 mol% or less, preferably 22 mol% or less.

Although NiZn ferrite can be used in the present invention, MnZn ferrite has a higher saturation magnetic flux density and permeability, and has a higher Fe2 valence concentration, and thus has a lower oxidation potential. Further, ferrites obtained by adding 5 mol% or less of an additive made of oxides such as Ti, Zr, Si, Ge, Sn, Li, Mg, and Cu to these ferrites can also be used in the same manner. Further, either polycrystalline or single crystal ferrite can be used in the present invention.

The high saturation magnetic flux density magnetic film used in the magnetic head of the present invention is FeAlSi (sendust) or FeGa.
Si-based, FeSi-based, FeTi-based, FeAl-based, FeC
Various high saturation magnetic flux density crystalline magnetic alloy films of the system can be used. Further, as the Fe-C / Ni-Fe multilayer film, a multilayer film in which a high saturation magnetic flux density magnetic film of about 50 nm is laminated with an intermediate layer of about 5 nm can be used.
Further, an amorphous alloy film containing Fe as a main component can be used. Since these contain Fe as a main component, the corrosion resistance deteriorates when used in a magnetic head compounded with ferrite. Therefore, when used in combination with the ferrite of the present invention, there is an effect of improving the corrosion resistance.

Further, Fe as a main component and C, N, B, O
Any one or more of and Ti, Zr, Hf, Nb, M
In the magnetic film containing at least one of o and W, the above-mentioned element dissolved in supersaturation is discharged from the Fe crystal grains to the periphery of the crystal grains by the heat treatment after the film formation, where (C, N, B ，
A strong compound consisting of a group of O) and a group of (Ti, Zr, Hf, Nb, Mo, W) is formed, and fine crystal grains are not coarsened, and high saturation excellent in thermal stability and soft magnetic characteristics. A magnetic flux density magnetic film is obtained. The magnetic film of this system is called a microcrystalline precipitation film. However, these microcrystalline deposited films have a problem of low corrosion resistance, and this problem is particularly noticeable when used in combination with ferrite.

In order to improve the corrosion resistance of the microcrystalline deposited film,
It is effective to add various additive elements as shown in the composition formula: Fe _a M _b T _c X _d Y _e R _f Z _g .

Here, Co and Ni shown in the element group M have the effect of improving the corrosion resistance without lowering the saturation magnetic flux density,
Since the magnetostriction constant increases when a large amount is added, it is used within the range of 40% or less.

Ti, Zr, Hf, N represented by the element group T
b, Ta, Mo, and W are C, N, and
It is an element that combines with B and O to refine the crystal and develop soft magnetic properties. Both have little effect when added in a small amount, and the saturation magnetic flux density significantly decreases when added in a large amount.
% To 20%, the element group Z is 1% to 20%
Use within the following range.

Ru, Rh, O represented by the additional element group X
s, Ir, Pd, Pt, Au, Ag, and Cu are elements that improve the corrosion resistance without lowering the saturation magnetic flux density. However, since the magnetostriction constant increases with the addition amount, it is used within the range of 15 at% or less.

Cr, V, Al, Si represented by the element group Y
Improves corrosion resistance. However, it is an element that lowers the saturation magnetic flux density. Further, Si and V have the function of lowering the magnetostriction constant, and are used within the range of 20 at% or less.

Y (yttrium) and the rare earth element represented by the element group R have the function of refining the crystal grains and further reducing the magnetostriction constant. However, when the addition amount is increased, the saturation magnetic flux density is lowered, so that it is used within the range of 10 at% or less.

As described above, the microcrystalline deposited film having the composition shown here has improved corrosion resistance and magnetic properties, but when used in combination with ferrite, a corrosion battery is formed and the corrosion resistance is not sufficient. There is. Therefore, when used in combination with the ferrite of the present invention, remarkably excellent corrosion resistance and recording / reproducing characteristics can be realized.

The magnetic film used in the magnetic head of the present invention is formed by a thin film forming technique such as a sputtering method or a vacuum evaporation method. In particular, it is preferable to use a sputtering method such as a bipolar sputtering method, a magnetron sputtering method, or an ion beam sputtering method. The microcrystalline deposited film used in the present invention is 400 ° C. after the magnetic film is formed.
The above heat treatment is added. By this heat treatment, from the film structure in which the respective elements are almost uniformly dispersed, at least about 50 nm or less containing Fe as a main component, usually about 20 n
The structure changes to a structure in which fine crystal grains of m or less and a fine compound of the element group T and the element group Z exist around the crystal grains.

In the magnetic head of the present invention, the high saturation magnetic flux density magnetic film is used in at least a part of the magnetic core near the cap. The magnetic head of the present invention can be used as a thin film magnetic head for a magnetic disk. Further, it can be used for a MIG head used for magnetic disks and VTRs, in which a high saturation magnetic flux density magnetic film is formed on the gap surface of a ferrite head. Further, it can be used for a VTR composite head in which a high saturation magnetic flux density magnetic film is formed near the gap of the ferrite head so that the interface between the ferrite and the magnetic film is not parallel to the gap surface.

[0035]

EXAMPLES Next, the present invention will be described with reference to examples.

Example 1 FIG. 1 shows the results of measuring the electrochemical polarization curves of the MnZn ferrite single crystal produced by the Bridgman method and the FeTaC based magnetic film which is a high saturation magnetic flux density microcrystalline film. In the figure, ferrite 1
Is Fe ₂ O ₃ 55.5 mol% used in the magnetic head of the present invention,
A single crystal having a composition of MnO 26.5 mol% and ZnO 18 mol%, ferrite 2 and ferrite 3 are Fe ₂ O ₃ 54 mol% and MnO 33 m used in a conventional magnetic head.
single crystal having a composition of ol%, ZnO 13 mol%, and Fe ₂ O ₃ 53.5 mol%, MnO 28.5 mol%, ZnO 1
It is a single crystal having a composition of 8 mol%.

The FeTaC film is a sample prepared by a high frequency bipolar sputtering method and then heat-treated at 600 ° C. for 30 minutes, has a composition of Fe ₇₆ Ta ₁₁ C ₁₃ (at%), and has a saturation magnetic flux density of 1 The characteristics were 0.53 T, coercive force 0.3 Oe, and magnetostriction constant 0.7 × 10 ^-6 . As a result of observing this magnetic film with a transmission electron microscope, the average crystal grain size is 15 nm.
Met. A borate buffer solution with a pH of 8.3 was used to measure the polarization curve.
Normal NaCl was added. The test temperature is 30 ° C.

As shown in the figure, it can be seen that the FeTaC film, which is a microcrystalline deposited film, has a current flowing from a low potential of about -0.2 V, and dissolution by oxidation starts near this potential. on the other hand,
Fe ₂ O ₃ concentration used in conventional magnetic heads is 55 mol
% Ferrites 2 and 3 have an oxidation potential of about 0.8.
The potential is as high as V and 1.0V. Further, in the ferrite 1 used in the present invention and having a Fe ₂ O ₃ concentration of 55 mol% or more, a melting current flows from around 0 V, and oxidation starts near this potential. The Fe ₂ O ₃ concentration of high ferrite 1 is significantly lower oxidation potential as compared with Fe ₂ O ₃ low density ferrite 2 and 3 reason as is, Fe ₂ O ₃ in the high density ferrite Fe2 monovalent ions It is thought that this is due to the fact that there is a large amount of carbon dioxide, which is oxidized at a relatively low potential.

As described above, in the magnetic head in which the magnetic film having a low oxidation potential and the ferrite having a high oxidation potential are adjacent to each other, when moisture in the environment is condensed, a corrosive battery is formed between the ferrite and the magnetic film. Once formed, the magnetic film is significantly susceptible to corrosion. In order to prevent this, it is necessary to select a ferrite material having an oxidation potential close to that of the magnetic film, such as ferrite 1.

(Example 2) In order to confirm the effect of the above-mentioned oxidation potential, as shown in FIG. 2, MIG in which a high saturation magnetic flux density magnetic film was formed on the gap surface of a ferrite magnetic core.
A head was manufactured and the corrosion resistance and recording / reproducing characteristics of the head were evaluated. As the ferrite, MnZn ferrite single crystal is used, and the (110) plane is the side surface of the magnetic head, and (33)
The surface (2) corresponds to the gap surface and the surface (113) corresponds to the tape sliding surface. However, the influence of the selection of these crystal planes on the corrosion resistance was small, and the effect of the ferrite composition was recognized regardless of the crystal planes. The method for producing the magnetic film is the same as in Example 1. The film thickness of the magnetic film was 5 μm. For the evaluation of corrosion resistance, the magnetic head was immersed in a 1/2 normal NaCl solution, and the ratio of the head in which corrosion occurred on the tape sliding surface of the head after 200 hours of immersion was shown as the corrosion rate. Further, as a recording / reproducing characteristic, a coercive force of 1500
Using a metal tape of Oe, the recording / reproducing output was measured at a relative speed of 3.8 m / s and a frequency of 5 MHz. The results are shown in Table 1.
Shown in

[0041]

[Table 1]

As shown in Table 1, by setting the Fe ₂ O ₃ concentration of ferrite to 55 mol% or more, the occurrence rate of corrosion of the magnetic film was remarkably reduced. The higher the Fe ₂ O ₃ concentration, the more
It was observed that the higher the ZnO concentration, the higher the corrosion resistance. On the other hand, as in the case of the present invention 3, 4, 5, 6, Fe ₂ O ₃ concentration of 60
The output slightly decreased in the region of mol% or more and ZnO concentration of less than 15 mol%. It is considered that this is because the crystal magnetic anisotropy and the magnetostriction constant of ferrite increased and the magnetic permeability decreased. Further, as in the case of the present invention 7, the output slightly decreased even when the ZnO concentration was 22 mol% or more. It is considered that this is because the saturation magnetic flux density of the ferrite was lowered and the recording characteristics were mainly lowered.

(Embodiment 3) Next, the effect of the present invention was examined for various high saturation magnetic flux density magnetic films. Table 2 shows the results of evaluating the corrosion resistance of the magnetic head in the same manner as in Example 2.

[0044]

[Table 2]

As shown in Table 2, no matter which high saturation magnetic flux density magnetic film is used, the corrosion resistance can be remarkably improved by using the ferrite used in the present invention. This effect is particularly suitable for a magnetic head using a film having low corrosion resistance such as a microcrystalline deposition film, and Cr, Ru,
Even in the case of a fine crystal deposition film having improved corrosion resistance by adding Al, Rh, etc., the corrosion resistance deteriorates in the case of a magnetic head combined with a conventional ferrite. Therefore, in order to solve this problem, it is combined with the ferrite used in the present invention. Is effective. Further, as shown in Table 2, the magnetic film used in the present invention is not limited to the microcrystalline deposition film, but is also effective for the Fe-based high saturation magnetic flux density film such as FeSi-based or FeC-based alloy film and the multilayer film thereof.

In this embodiment, only the case of the MIG head is shown, but the effect of the present invention similarly occurs in the magnetic head in which the Fe-based high saturation magnetic flux density magnetic film and the ferrite are combined.

In the magnetic recording apparatus of the present invention, the magnetic head of the present invention is used for at least one of magnetic recording, reproduction, and erasing operations of a signal on a medium, or a plurality of kinds of these operations. This improves the corrosion resistance.

[0048]

As described above, the magnetic head of the present invention has particularly high corrosion resistance by combining the high saturation magnetic flux density magnetic film and the ferrite having the limited composition,
Realizes excellent recording / reproducing characteristics.

[Brief description of drawings]

FIG. 1 is a measurement diagram of electrochemical polarization curves of a high saturation magnetic flux density magnetic film and ferrite of the present invention and a conventional example.

FIG. 2 is a perspective view showing the structure of a magnetic head of the present invention.

Claims (13)

[Claims] 1. A magnetic core made of high-permeability ferrite,
In a magnetic head having a high saturation magnetic flux density magnetic film containing Fe as a main component in at least a part of the vicinity of the gap,
The concentration of Fe ₂ O _{3 in} the high magnetic permeability ferrite is 55 mol%
A magnetic head having a content of not less than 65 mol%. 2. The magnetic head according to claim 1, wherein the high magnetic permeability ferrite is MnZn ferrite. 3. The magnetic head according to claim 1, wherein the ZnO concentration is 10 mol% or more and 25 mol% or less. 4. The Zn according to claim 1, 2, or 3.
A magnetic head having an O concentration of 15 mol% or more and 22 mol% or less. 5. A magnetic head according to claim 1, 2, 3 or 4, wherein the concentration of Fe ₂ O ₃ is 60 mol% or less. 6. The method according to claim 1, 2, 3, 4 or 5.
A magnetic head in which the high saturation magnetic flux density magnetic film is a magnetic film containing 50 at% or more of Fe. 7. The high saturation magnetic flux density magnetic film according to claim 6, wherein the content of Fe is 50 at% or more and C, N, B, Si, A.
0.1% of one or more of l and Ti
A magnetic head containing at least 20 at%. 8. The high saturation magnetic flux density magnetic film according to claim 6, wherein Fe is 50 at% or more and any one or more elements of C, N, B and O are 1 at% or more and 20 at%.
A magnetic head containing 2 at% or more and 20 at% or less of any one or more of Ti, Zr, Hf, Nb, Mo and W below. 9. The high saturation magnetic flux density magnetic film according to claim 8, which is represented by a composition formula: Fe _a M _b T _c X _d Y _e R _f Z _g , wherein the element group M is Co or Ni. One or more of the elements, the element group T is one or more of Ti, Zr, Hf, Nb, Ta, Mo and W, and the element group X is Ru, Rh, Os, Ir, Pd, Pt,
One or more of Au, Ag, and Cu, the element group Y is Cr,
One or more of V, Al and Si, the element group R is one or more of Y (yttrium) and a rare earth element, and the element group Z is one or more of C, N, B and O, and b ≦ 40,2
≤c≤20, 0≤d≤15, 0≤e≤20, 0≤f≤1
0, 1 ≦ g ≦ 20, a + b + c + d + e + f + g = 10
A magnetic head having a composition of 0 (where a, b, c, d, e, f, and g are at%). 10. The magnetic head according to claim 6, 7, 8 or 9, wherein the high saturation magnetic flux density magnetic film has an average crystal grain size of 50 nm or less. 11. The average crystal grain size of the high saturation magnetic flux density magnetic film according to claim 6, 7, 8, 9, or 10.
A magnetic head of m or less. 12. A method according to claim 6, 7, 8, 9, 10 or 11.
2. A magnetic head in which a high saturation magnetic flux density magnetic film having the above composition is laminated using a thin film having another composition as an intermediate layer. 13. Claims 1, 2, 3, 4, 5, 6, 7,
8. A magnetic recording device using at least one of the magnetic heads 8, 9, 10, 11 or 12.