JPH0827910B2 - Magnetic head - Google Patents

Description

The present invention relates to a magnetic head, and more particularly to a video tape recorder (VTR) and a digital audio tape recorder (DA).
The present invention relates to a magnetic head used in a magnetic recording / reproducing apparatus such as T).

(B) Conventional Technology In recent years, in a magnetic recording / reproducing device such as a VTR or a DAT, the density of recording signals has been increased. Corresponding to this high density recording, a metal tape having a high coercive force using a ferromagnetic metal powder such as Fe, Co or Ni as a magnetic powder has been used. For example, a small VT called 8mm video
For R, a metal tape having a high coercive force of Hc = 1400 to 1500 Oersted is used. The reason is that there is a demand for a recording medium capable of shortening the signal recording wavelength because of the necessity of increasing the recording density in order to downsize the magnetic recording / reproducing apparatus.

On the other hand, if a conventional magnetic head made of only ferrite is used for recording on this metal tape, the saturation magnetic flux density of ferrite is at most about 5500 gauss, and the magnetic saturation phenomenon occurs. Cannot be used for. Therefore, as a magnetic head corresponding to the metal tape having the high coercive force, in addition to the wear resistance of the high frequency characteristics of the magnetic core normally required as the magnetic head, the saturation magnetic flux density in the vicinity of the gap of the magnetic core is It is required to be large. As a magnetic head compatible with a metal tape satisfying this requirement, a magnetic magnetic material having a saturation magnetization larger than that of ferrite used as a magnetic core (for example, permalloy, sendust, A magnetic head composed of an amorphous magnetic material (referred to as a composite magnetic head) has been proposed. This composite type magnetic head has excellent characteristics such as reliability, magnetic characteristics, and wear resistance.

FIG. 16 is a perspective view showing the appearance of a conventional magnetic head. As shown in FIG. 16, a pair of magnetic core halves (1a) (1b) made of a ferromagnetic oxide such as Mn-Zn ferrite are butted against each other through a non-magnetic material to form an operating gap (2). A ferromagnetic metal thin film (3) such as sendust having a high saturation magnetic flux density is formed in the vicinity of the. The magnetic core halves (1a) (1b) are joined by glass (4) to form a winding groove (5).

In the case of the composite magnetic head as described above, the ferromagnetic metal thin film (3) is deposited and formed on the upper surface of the substrate made of the ferromagnetic oxide subjected to the mirror surface treatment by sputtering.
However, the vicinity of the junction interface between the ferromagnetic metal thin film and the substrate made of ferromagnetic oxide is demagnetized due to mutual diffusion of component elements, chemical reaction, incompatibility of crystal structure, etc., and acts as a pseudo gap. It adversely affects the performance as a head.

That is, as shown in FIG. 16, in addition to the original working gap (2), a pseudo gap is formed at the boundary surface (6) between the magnetic core halves (1a) (1b) and the ferromagnetic metal thin film (3). To be done. For example, when the isolated reversal magnetization on the magnetic tape is reproduced by using the magnetic head having the boundary surface (6) where such a pseudo gap is formed, the original signal (7) is obtained as shown in FIG. On the other hand, the pseudo signals (8a) and (8b) are reproduced before and after the time τ = t / v. Note that t is the thickness of the ferromagnetic metal thin film (3) in the head-tape relative running direction, and v is the relative running speed between the head and tape.

Further, when reproducing the continuous reversal magnetization whose recording wavelength λ is equal to or shorter than t, it is difficult to directly observe the pseudo signals (8a) and (8b) as shown in FIG. However, if the frequency characteristic of the reproduction output is measured, as shown in FIG. 19, f == due to the superposition of the reproduction output due to the original working gap (2) and the reproduction output due to the pseudo gap.
At the frequency satisfying n · (v / t), f = (n−1 /
2) A frequency characteristic curve with undulations that forms a valley at frequencies that satisfy (v / t) is obtained. In addition, n is a natural number and f is a frequency (v / λ). Therefore, if a magnetic head having a boundary surface (6) in which such a pseudo gap is formed is used in a VTR, a DTA or the like, a pseudo signal due to the pseudo gap becomes noise, which adversely affects image quality deterioration or error rate increase. Affects the performance as a magnetic head. In particular, when a magnetic head in which the boundary surface (6) where a pseudo gap occurs and the working gap (2) are parallel to each other as shown in FIG. It causes deterioration of the ratio.

In order to suppress the occurrence of the pseudo gap as described above, a method of performing reverse sputtering on the surface of the substrate made of a ferromagnetic oxide such as ferrite under the condition of an appropriate input power immediately before forming the ferromagnetic metal thin film, For example, it is disclosed in JP-A-62-57115 (G11B5 / 133).
However, even with this method, there is a problem that the work-affected layer that causes the pseudo gap cannot be completely removed, and the generation of the pseudo gap cannot be suppressed sufficiently.

Furthermore, as shown in FIG. 17, the magnetic core half body (1a)
The interface (6) between the ferromagnetic metal thin film (1) and the ferromagnetic metal thin film (3) is made non-parallel by inclining it with respect to the surface where the working gap (2) is formed, so that even if a pseudo gap occurs, the head There has been proposed a composite magnetic head that does not adversely affect the performance of the above. However, the magnetic head having such a structure has a more complicated manufacturing process and a higher cost than the magnetic head in which the boundary surface (6) and the working gap (2) shown in FIG. 16 are parallel. Therefore, it is not suitable for mass production.

In addition, the inventors of the present application, the parallel type MIG shown in FIG.
Attention is paid to the following three points as a cause of the generation of the pseudo gap in the magnetic head having the (Metal In Gap) structure.

(I) Deterioration of the crystallinity of the surface of the substrate made of a ferromagnetic oxide such as ferrite (ii) Amorphization of the initial layer of a ferromagnetic thin film made of a ferromagnetic metal material such as sendust (iii) A ferromagnetic metal thin film Or chemical reaction at the bonding interface between the substrate and a substrate made of a ferromagnetic oxide (c) Problems to be solved by the invention The present invention has been made in view of the drawbacks of the above-mentioned conventional example, and it has been proposed that a magnetic core half body and a strong magnetic core are used. An object of the present invention is to provide a magnetic head capable of suppressing occurrence of a pseudo gap at a bonding interface with a magnetic metal thin film as much as possible, or sufficiently suppressing an adverse effect caused by the bonding interface operating as a pseudo gap. is there.

(D) Means for Solving the Problems A magnetic head according to the present invention is a magnetic head in which a pair of magnetic core halves are butted against each other through a non-magnetic material to form an operating gap. A pair of magnetic core halves having gap forming surfaces to be butted to form the working gap, an intervening thin film formed on the gap forming surface and made of a non-magnetic oxide, and the intervening thin film. And a ferromagnetic thin film made of a metallic material having ferromagnetism, wherein the ferromagnetic thin film is a thin film having crystal grains grown from just above the surface of the intervening thin film. A crystal grain having a (110) plane parallel to the gap forming surface, and a crystal grain having a (200) plane parallel to the gap forming surface,
A crystal grain having a (211) plane parallel to the gap forming plane is included.

(E) Operation When a ferromagnetic thin film is formed on the gap forming surface made of ferromagnetic oxide, the initial layer of the film has an atomic arrangement due to the inconsistency of the crystal structure with the underlying surface. There is a possibility of becoming a disordered magnetic deterioration layer. According to the magnetic head of the present invention, a thin film made of a nonmagnetic oxide is interposed between the magnetic core half body made of a ferromagnetic oxide and the ferromagnetic thin film.
This non-magnetic oxide thin film has an effect of blocking the influence of the atomic arrangement on the surface of the magnetic core half body made of a ferromagnetic oxide on the formation process of the initial layer of the ferromagnetic metal thin film. Therefore, the ferromagnetic metal thin film formed on this non-magnetic oxide thin film has crystal grains having (110) planes parallel to the gap formation surface and (200) parallel to the gap formation surface from the initial formation layer. The film is grown as a film including crystal grains having a plane and crystal grains having a (211) plane parallel to the gap formation surface.
Therefore, since the magnetic deterioration layer in which the atomic arrangement is disturbed is not formed in the initial layer of the ferromagnetic thin film, the factor causing the pseudo gap can be eliminated. As a result, it is possible to suppress the deterioration of the reproduction output of the magnetic head due to the pseudo gap.

That is, according to the present invention, by forming the non-magnetic oxide thin film on the gap forming surface made of the ferromagnetic oxide, it is possible to prevent the amorphization of the ferromagnetic metal thin film initial layer which causes the pseudo gap. obtain.

(F) Example Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

As shown in Fig. 1, Mn-Zn single crystal or polycrystalline ferrite, Ni-Zn single crystal or polycrystalline ferrite,
A non-magnetic oxide thin film (10) is formed on the gap forming surface of a magnetic core half body (9a) (9b) of a ferromagnetic oxide such as a ferro sprayer. This non-magnetic oxide thin film (10) is a non-magnetic oxide containing a semi-metal element such as Si or Ge, or a metal element such as Mg, Al, Zn, Ti, Cr, Zr, Mo, Ta or W. It is made of a non-magnetic oxide containing a and is formed as a thin film having a thickness of several nm to several tens nm by a vapor-phase quenching method such as a sputtering method.

In this case, the gap forming surface on which the non-magnetic oxide thin film (10) is formed is subjected to at least an etching treatment, or after the etching treatment is performed, the magnetic core is cleaned by reverse sputtering. It suffices if the planes of the as-grown ferromagnetic oxide crystals forming the halves (9a) and (9b) are exposed. On the non-magnetic oxide thin film (10), polycrystalline substances such as sendust alloy, permalloy alloy, Fe-Al alloy, Fe-Co alloy, Fe-Si alloy, Fe-C alloy, etc. A ferromagnetic metal thin film (11) made of is formed by sputtering. The working gap (12) located between the ferromagnetic metal thin films (11) is made of Si.
It is composed of a non-magnetic thin film such as O ₂ , TiO ₂ , Al ₂ O ₃ , Ta ₂ O ₅ , Ti and Cr. The magnetic core halves (9a) (9b) are joined by glass (13). A winding groove (14) is formed in the magnetic core halves (9a) (9b) joined by the glass (13).

In addition, referring to FIG. 2, the ferromagnetic metal thin film (11) has a thickness of 1 to 10 μm, and the working gap (12) has a thickness G of 0.1 to 10 μm.
1 μm, preferably 0.2 to 0.4 μm, the thickness δ of the non-magnetic oxide thin film (10) is 1 nm or more, 1/1 of the working gap length G.
It is 0 or less.

Next, an embodiment of a method of manufacturing a magnetic head according to the present invention will be described.

First, mirror-polishing is performed using diamond abrasive grains or the like on the upper surface that is the gap forming surface of the substrate made of Mn-Zn single crystal ferrite. After that, the work-affected layer on the upper surface of the substrate formed by the polishing treatment is removed by the etching treatment with a phosphoric acid aqueous solution or the like. The ferrite substrate (17) having the etched gap forming surface is mounted in the sputtering apparatus shown in FIG. 15, which is kept in a high vacuum. Impurities adhering to the upper surface of the ferrite substrate (17) are removed by reverse-sputtering the gap forming surface with inert gas ions such as Ar ⁺ generated by the glow discharge. In FIG. 15, the ferrite substrate (17) is attached to the second plate (42) set to the negative potential, and the first plate (41) is set to the positive potential. An inert gas such as Ar or He is introduced into the container (40),
High frequency power is applied to the plate (41) and the second plate (42) by the external AC power supply (43). In this way, reverse sputtering is applied to the gap forming surface (23) of the ferrite substrate (17) mounted in the sputtering device.

Next, a nonmagnetic oxide thin film made of SiO ₂ is formed on the gap forming surface of the ferrite substrate by sputtering, and a ferromagnetic metal thin film made of sendust is formed on this nonmagnetic oxide thin film by sputtering.

The step of forming the nonmagnetic oxide thin film and the step of forming the ferromagnetic metal thin film are performed using the sputtering apparatus shown in FIG. A positive potential is set on the second plate (42) to which the ferrite substrate (17) is attached, and the first plate (4) facing the ferrite substrate (17).
In 1), a target made of SiO ₂ as an example of a material forming the non-magnetic oxide thin film or Sendust as an example of a ferromagnetic metal material is attached and set to a negative potential. A nonmagnetic oxide thin film made of SiO ₂ is formed on the upper surface of the ferrite substrate (17) by sputtering so as to have a film thickness of about 5 nm.

Furthermore, a ferromagnetic metal thin film made of sendust is deposited on the non-magnetic oxide thin film by about 3 μm by sputtering.
It is formed to have a film thickness of about m. On this ferromagnetic metal thin film, a non-magnetic thin film made of SiO ₂ that forms the working gap is formed to have a film thickness of about 0.1 μm.

In this case, the conditions for forming the ferromagnetic metal thin film are, for example,
The conditions are as follows. When using a high-frequency magnetron sputtering device, the ferrite wafer is placed facing the target made of sendust alloy, and 5 × 10
^{After the} container (40) is evacuated to a high vacuum of ^-6 Torr or less, RF is applied with an input power of 500 W in an atmosphere of Ar gas pressure of 5 × 10 ^-3 Torr.
(Radio Frequency) Discharge causes film formation by sputtering. It is generally considered that the sendust film formed by the sputtering method needs to be heat-treated in order to obtain good soft magnetic characteristics. This heat treatment is performed in the glass welding process for joining the magnetic core halves in the process of manufacturing the magnetic head to which the present invention is applied.

3 (a) and 3 (b), the non-magnetic oxide thin film (10), the ferromagnetic metal thin film (11), and the working gap are formed on the upper surface of the ferrite substrate (17) by the above steps. The magnetic core half members (9a) and (9b) in which the constituent non-magnetic thin films (12) are sequentially formed are shown.

Next, referring to FIG. 4 (a) and FIG. 4 (b),
The track width regulating grooves (16a) (16b) (16c) (16) are left on the upper surfaces of the magnetic core half members (9a) (9b) by leaving only the track widths (15a) (15b) corresponding to the gap butting portions.
d) is formed by ion beam etching or the like.

Further, as shown in FIGS. 5 (a) and 5 (b), the upper surface of the ferrite substrate (17) is wound with grooves (13a) (13b) filled with glass for joining magnetic core half members. The line groove (14) and the glass rod insertion groove (13c) are formed using a rotary grindstone or the like. Then, by inserting the glass rod into the glass rod insertion groove (13c) and pressing and heating the magnetic core half members (9a) and (9b) in a state where the gap equivalent portions of the magnetic core half members (9a) and (9b) are abutted, 9a) and (9b) are glass-bonded to form a block.

In this way, the block (18) shown in FIG. 6 is completed. This block (18) is cut into core blocks along the line AA ', and each tape sliding contact surface is R-polished. In addition, B-
By slicing along the line B ', the magnetic head chip of the present invention shown in FIG. 1 is completed.

According to the manufacturing method of the above-mentioned embodiment, as shown in FIG. 9, a non-magnetic oxide thin film (10) made of SiO ₂ was formed on the gap forming surface (23) of the substrate (17) made of Mn-Zn single crystal ferrite. ) Is interposed to form a ferromagnetic metal thin film (11) made of sendust. At this time, the ferromagnetic metal thin film (1
The X-ray diffraction pattern using CuKα ray for each film thickness of 1) is shown in FIG. 7. The gap forming surface (23) is Mn−
This is the (100) plane of Zn-based single crystal ferrite.

According to the X-ray diffraction pattern shown in FIG. 7, the gap forming surface (2
The planes parallel to 3) are (110) planes and (200) planes of body-centered cubic in Sendust that constitutes the ferromagnetic metal thin film (11).
An angle of 44.6 ° (approx. 45 °) indicating that it is the (211) plane, 65.
Peaks are detected at 0 ° (about 65 °) and 82.4 ° (about 82 °). In this case, even when a ferromagnetic metal thin film made of sendust with a thickness of 200 Å (20 nm) is formed,
X-ray diffraction peaks corresponding to each crystal face of the body-centered cubic crystal are detected. This means that when a non-magnetic oxide thin film (10) made of SiO ₂ having a film thickness of about 5 nm is interposed, a ferromagnetic ferromagnetic material having crystallinity is formed immediately above the surface of the non-magnetic oxide thin film (10). This means that a metal thin film (11) is formed.
As shown in FIG. 9, this ferromagnetic metal thin film (11)
Is a crystal grain (19) having a (110) plane as a plane substantially parallel to the gap forming plane (23) as a film-forming base plane, and (2
It is composed of a body-centered cubic polycrystal having a crystal orientation including a crystal grain (20) having a (00) plane and a crystal grain (21) having a (211) plane.

As a comparative example, using the manufacturing method of the above example, the tenth
As shown in the figure, the substrate (17) made of Mn-Zn single crystal ferrite is composed of sendust directly on the (100) plane as the gap forming surface (23) without interposing a non-magnetic oxide thin film. A ferromagnetic metal thin film (22) is formed. X using CuKα ray at each thickness of the ferromagnetic metal thin film at this time
The line diffraction pattern is shown in FIG.

According to the X-ray diffraction pattern shown in FIG. 8, the plane substantially parallel to the gap forming surface (23) of the ferrite substrate (17) which is the film-forming underlayer constitutes the ferromagnetic metal thin film (22). In Sendust, a peak is detected only at an angle of 44.6 ° (about 45 °), which indicates a body-centered cubic (110) plane. Further, as shown in FIG. 10, the initial layer (22a) of the ferromagnetic metal thin film (22) made of sendust formed directly on the ferrite substrate (17) has an inconsistent crystal structure with the underlying surface. For example, it is formed as a magnetic deterioration layer in which the atomic arrangement is disturbed, that is, an amorphous layer. for that reason,
When a sendust film having a thickness of 500 Å (50 nm) or less corresponding to the initial layer (22a) is formed, a peak corresponding to a specific crystal plane is not detected as shown in FIG. The presence of the amorphous layer at the sendust / ferrite interface causes the generation of the pseudo gap. That is, as shown in FIG. 10, the ferromagnetic metal thin film (22) directly formed on the ferrite substrate (17) is used as an initial layer (22a) composed of an amorphous layer and a film-forming base surface. A body-centered cubic polycrystal having a crystal orientation consisting only of crystal grains (19) having a (110) plane substantially parallel to the gap forming surface (23).

In FIGS. 9 and 10, even if the film thickness of the ferromagnetic metal thin films (11) and (22) is further increased to 1 μm or more, the positions of the peaks shown in FIGS. 7 and 8 do not change. It was

FIG. 11 is a diagram showing a frequency characteristic curve of reproduction output measured using a magnetic head according to the present invention in which a sendust film is formed by interposing an SiO ₂ film on a ferrite gap forming surface. Is. As a comparative example, FIG. 12 is a diagram showing a frequency characteristic curve of reproduction output measured by using a magnetic head having a sendust film formed directly on the gap forming surface of ferrite. In both magnetic heads, the gap length G was 0.25 μm, the thickness of the sendust film was 3 μm, and the thickness of the SiO ₂ film interposed between the ferrite and the sendust film was 50Å (5 nm). The measurement of the frequency characteristic curve uses a metal tape having a holding force Hc of about 1400 Oersted (Oe), and records a frequency sweep signal of 0.1 to 10 MHz under the condition of the relative traveling speed v between head and tape v = 3.1 m / s, The reproduction output was detected by using a spectrum analyzer.

As is clear from FIG. 12, when a magnetic head in which the sendust film is formed directly on the ferrite gap forming surface is used, a large undulation occurs in the frequency characteristic of the reproduction output. On the other hand, as shown in FIG. 11, when the magnetic head of the present invention is used, the frequency characteristics of the reproduction output hardly undulate. This means that by forming the sendust film with the SiO ₂ film interposed on the ferrite gap forming surface, it is possible to prevent the initial layer of the sendust film, which causes a pseudo gap as a magnetic deterioration layer, from being amorphized. It is considered to be a thing.

In the magnetic head according to the embodiment of the present invention, as shown in FIG. 9, the ferromagnetic metal thin film (11) made of sendust has three kinds of crystal grains (19) (having different crystal orientations). 20) and (21) are included. Therefore, when the ion beam etching treatment shown in FIGS. 4 (a) and 4 (b) is performed in the above-mentioned manufacturing method, the crystal grains (19) (20) (of the ferromagnetic metal thin film (11) ( Due to the difference in the etching rate of 21), unevenness occurs on the surface of the ferrite substrate (17) exposed at the end of etching. Whether or not the ferromagnetic metal thin film (11) formed on the ferrite substrate (17) contains three kinds of crystal grains (19) (20) (21) by detecting this unevenness during the manufacturing process. It becomes possible to inspect.

FIG. 13 shows that a ferromagnetic metal thin film (11) made of sendust having a thickness of 1 μm is formed by interposing a non-magnetic oxide thin film (10) made of SiO ₂ according to the above embodiment, and then a ferromagnetic metal thin film ( It is a figure which shows the measurement result of the surface roughness of a ferrite substrate (17) when removing 11) using an ion beam etching process. In addition, FIG. 14 shows, as a comparative example, a ferromagnetic metal thin film (22) made of sendust having a thickness of 1 μm is formed directly on a ferrite substrate (17), and then the ferromagnetic metal thin film (22) is formed. It is a figure which shows the measurement result of the surface roughness of a ferrite substrate (17) when it removes using an ion beam etching process. Referring to these figures, after forming the ferromagnetic metal thin film (11) according to the above-mentioned embodiment,
Those who have undergone ion beam etching (Fig. 13)
It is understood that the surface roughness of the ferrite substrate (17) is larger than that of the comparative example (Fig. 14). When actually manufacturing a magnetic head, the thickness of the ferromagnetic metal thin film is generally 1
It is at least μm, and the above-mentioned difference in surface roughness can be clearly distinguished by visual observation.

(G) Effect of the Invention As described above, according to the present invention, a ferromagnetic metal thin film is formed by interposing a nonmagnetic oxide thin film on the gap forming surface of a magnetic core half body made of a ferromagnetic oxide. Amorphization of the ferromagnetic thin film initial layer, which causes a pseudo gap, can be prevented. As a result, it is possible to minimize the deterioration of the reproduction output of the magnetic head due to the pseudo gap.

[Brief description of drawings]

1 to 6 relate to the present invention, FIG. 1 is a perspective view showing the appearance of a magnetic head, and FIG. 2 is a view showing the main part of a tape sliding contact surface of the magnetic head, FIG. 3, FIG. FIGS. 5, 5 and 6 are perspective views showing a method of manufacturing a magnetic head, respectively. Seventh
Figures 8 and 9 show the X-ray diffraction pattern of the ferromagnetic metal thin film, Figures 9 and 10 show the crystal structure of the ferromagnetic metal thin film, and Figures 11 and 12 show the reproduction output. FIG. 13 is a diagram showing the frequency characteristics of FIG. 13, FIG. 13 and FIG. 14 are diagrams showing the surface roughness measurement results, and FIG. 16 and 17 are perspective views showing the external appearance of a conventional magnetic head, FIG. 18 is a view showing a reproduced signal, and FIG.
The figure shows the frequency characteristics of the reproduction output. (9a) (9b) ... magnetic core half, (10) ... non-magnetic oxide thin film (intervening thin film), (11) ... ferromagnetic metal thin film, (1
2) …… Actuation gap, (19) (20) (21) …… Crystal grains, (23) …… Deposited substrate surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takao Yamano 2-18 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd. (72) Inventor Kazuo Ino 2-18-2 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric (72) Inventor Kozo Ishihara 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (72) Inventor Tsukasa Shimizu 2-18 Keihan Hondori, Moriguchi City, Osaka Sanyo Electric Co., Ltd. (56) References JP-A-2-192006 (JP, A) JP-A 1-220208 (JP, A) JP-A 64-7308 (JP, A) JP-A 61-74110 (JP, A)

Claims (5)

[Claims] 1. A magnetic head in which a pair of magnetic core halves are butted through a non-magnetic material to form an operating gap, the magnetic head being made of a ferromagnetic oxide and being butted to form the operating gap. Pair of magnetic core halves having a gap forming surface, an intervening thin film formed on the gap forming surface and made of a non-magnetic oxide, and a metallic material having ferromagnetism formed on the intervening thin film. And a ferromagnetic thin film comprising a ferromagnetic thin film having crystal grains grown from immediately above the surface of the intervening thin film, wherein the ferromagnetic thin film is parallel to the gap forming surface. A grain having a (110) face, a grain having a (200) face parallel to the gap forming face, and a grain having a (211) face parallel to the gap forming face. Magnetic De. 2. The magnetic head according to claim 1, wherein the thickness of the intervening thin film is 1 nm or more and 1/10 or less of the thickness of the working gap. 3. The magnetic head according to claim 1, wherein the intervening thin film is made of an oxide containing Si. 4. The magnetic head according to claim 1, wherein the crystal grains of the ferromagnetic thin film have a body-centered cubic crystal structure. 5. The magnetic head according to claim 1, wherein the ferromagnetic oxide is single crystal ferrite.