JPH038105A - Magnetic head - Google Patents

Abstract

PURPOSE:To improve the reproducing efficiency and the recording efficiency of the head by forming a magnetic domain structure of a magnetic core to a laminar reflux magnetic domain structure in its operation gap part. CONSTITUTION:The lower magnetic core 1 is brought to film formation in a recessed part provided on a substrate consisting of, for instance, a non- magnetic ceramics material, and thereafter, shaped to a prescribed shape and manufactured. Thereafter, an insulating film 4 is formed, a head driving thin film coil 5 is formed on the insulating film 4, and thereafter, the insulating film 4 is formed on a thin film coil 5 again. Subsequently, a through-hole is formed in a prescribed part of the insulating film 4, and thereafter, in a front part of the lower magnetic core 1, a gap control film is formed by a non- magnetic insulating material of Cr, SiO2, etc. Thereafter, the upper magnetic core 2 is formed and in the front part, an operation gap 6 is formed by joining the lower magnetic core 1 and the upper magnetic core 2 through the gap control thin film, and also, in the rear part, both of them 1, 2 are connected directly. Thereafter, by executing the heat treatment in a magnetic field, a protective film 7 of ceramics is formed and after controlling an anisotropic constant and an easy axis, assembly working is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used in video tape recorders, magnetic disk recording and reproducing devices, and the like. The present invention relates to a magnetic head such as a thin film magnetic head having a magnetic core made of a 6B metal thin film, and particularly to the magnetic domain structure of the magnetic core.

[Prior Art] Conventionally, the structure of the magnetic core of a thin-film magnetic head was reported in [Thin-film head for hard disk drives (Applied Magnetic Recording Research Group material MSJ39-5)] reported by Narishige et al., and is shown in Fig. 6. As shown, it had a planar circulating magnetic domain structure.

In FIG. 6, 50 is a magnetic body (magnetic core), 51 is a domain wall, 52a and 52b are magnetization directions, and 53 is a magnetic flux propagation direction. As shown in the figure, a magnetic body 50
At the center, the magnetization direction 52a is perpendicular to the magnetic flux propagation direction 53, and at the ends, the magnetization direction 52b is parallel to the magnetic flux propagation direction 53.

[Problems to be Solved by the Invention] Incidentally, in the above-mentioned prior art, no consideration was given to the effective cross-sectional area of the magnetic flux propagation path.

That is, when the magnetic body 50 has a planar circulating magnetic domain structure as shown in FIG. 6, the magnetization in the central portion is perpendicular to the magnetic flux propagation direction 53 as shown at 52a.
It has high magnetic permeability and sufficient magnetic flux propagation efficiency. However, at the end, as shown at 52b, the magnetization is parallel to the magnetic flux propagation direction 53, so the magnetic permeability is very small and does not contribute to effective magnetic flux propagation. Therefore, the effective magnetic flux propagation path The cross-sectional area is smaller than the cross-sectional area of the magnetic body 50.

When the above-mentioned situation occurs in the magnetic core, it immediately leads to an increase in magnetic resistance, leading to a decrease in head reproducing efficiency.

An object of the present invention is to provide a magnetic head in which the effective cross-sectional area of the magnetic flux propagation path matches the cross-sectional area of the head core, thereby improving head reproduction efficiency.

[Means for Solving the Problems] The above objects of the present invention are achieved by making the magnetic domain structure of the magnetic core a layered circulating magnetic domain structure at least in the working gap portion.

[Function] The relationship between the magnetic flux propagation direction and the magnetization direction when the layered circulating magnetic domain structure is realized will be explained using FIG. 5.

As shown in the figure, the magnetic flux propagation direction 31 and the magnetization directions 32a and 32b of the amorphous body 30 are orthogonal to each other at any location. Therefore, unlike the case of the planar circulation magnetic domain structure shown in FIG. 6, there is no difference in magnetic flux propagation efficiency depending on location. In addition.

In the figure, 33 indicates an m wall.

A layered perfusion domain structure appears only when its free energy is small compared to the free energy of a planar perfusion domain structure. As a result of theoretical and experimental studies regarding the core magnetic properties and the shape of the sliding surface, the inventors of the present application found that when the following conditions are satisfied, an N-shaped circulating magnetic domain structure appears with good reproducibility.

However, in the above formula, T is the total value of the upper and lower core thickness of the sliding surface,
A is the conversion stiffness constant of the core material, Ku is the magnetic anisotropy constant, W is the magnetic core width, and N is a natural number.

[Example] Examples of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 is a perspective explanatory view showing a magnetic core and a thin film coil of a thin film magnetic head, and FIG. 2 is a front view of a main part of a sliding surface.

In FIG. 1, 1 is a lower magnetic core, 2 is an upper magnetic core, and in this embodiment, both 1 and 2 are Co-Nb-Zr films (saturated magnetic flux Density: 0.95T), and is formed and shaped by known thin film forming techniques such as sputtering and photolithography. Also, the track width W shown in FIG. 2 is 48
The thickness T4 of the lower magnetic core 1 is 35 μm, the thickness T2 of the upper magnetic core 2 is 20 μm, and the total core thickness T is set to 55 μm. In addition, in Figure 1, 3
1 indicates the direction of magnetic flux propagation, 32a and 32b indicate the direction of magnetization,
33 indicates a domain wall.

The lower magnetic core 1 is produced, for example, by forming a film in a recess provided in a substrate 3 made of a non-magnetic ceramic material, and then shaping the film into a predetermined shape. After this.

After forming the insulating film 4 and forming the thin film coil 5 for driving the head on the insulating film 4, the insulating film 4 is again formed on the thin film coil 5.
form. Next, after forming a through hole in a predetermined portion of the insulating film 4, a gap regulating film is formed on the front portion of the lower magnetic core 1 using a nonmagnetic material (for example, a nonmagnetic insulating material such as Cr or SiO2). After that, the upper magnetic core 2 is formed, and the lower magnetic core 1 and the upper magnetic core 2 are joined at the front part through a gap regulating thin film to form an operating gap 6, and at the rear part, both 1 and 1 are joined. ,2
Connect directly.

Then, for anisotropy constant and easy axis control, in a magnetic field (
Heat treatment (magnetic field: 11 KOe) at 400°C.

30 minutes), a protective film 7 is formed using a ceramic thin film, and finally an assembly process is performed to complete the film magnetic head.

As a result of observing the magnetic domain structure of the thin film magnetic head shown in FIGS. 1 and 2 prepared by the above method using the Bitter method and the microcar effect, it was confirmed that a layered circulating magnetic domain structure had appeared.

FIG. 3 shows the frequency characteristics of the reproduction output of the thin film magnetic head having a layered perfusion magnetic domain structure according to the above-described embodiment of the present invention and the conventional thin film magnetic head having a planar perfusion magnetic domain structure. The plotted characteristic line A shows the thin film head according to the embodiment of the present invention, and the characteristic line B plotted with one mark shows the conventional example. As is clear from the figure,
The reproduction output of the thin film magnetic head with the layered circulating magnetic domain structure according to the present invention is 2 times higher than that of the conventional planar circulating magnetic domain structure.
It is improved by ~4dB.

In FIG. 4, reference numeral 5 shows a ward structure when the core width W is constant and the anisotropy constant and core film thickness are varied.

The 0 dotted line indicating the conditions under which O indicates a planar circulating magnetic domain structure and . indicates a condition under which a layered circulating magnetic domain structure appears, is calculated using the above-mentioned relational expression (1) for Ku, W, and T.

As is clear from the figure, it is clear that a single-layer circulating magnetic domain structure can be obtained if the condition of relational expression (1) is satisfied. Note that the anisotropic magnetic field was controlled by the heat treatment temperature in the magnetic field.

In the above embodiments, the entire magnetic core has a layered circulating magnetic domain structure, but the same effect can be expected even if only the narrow gap forming part (front part) of the magnetic core has a layered circulating magnetic domain structure. Furthermore, in addition to so-called thin-film magnetic heads in which the instant-acting coil is a thin-film coil, there are also magnetic heads of a type in which a metal magnetic thin film is coated as the core main body on a core base made of a non-magnetic or magnetic material. The invention is applicable.

[Effects of the Invention] As described above, according to the present invention, the effective cross-sectional area of the magnetic flux propagation path is expanded, and head reproducing efficiency and recording efficiency can be improved.

[Brief explanation of drawings]

1 and 2 relate to a thin film magnetic head according to an embodiment of the present invention, in which FIG. 1 is a simplified perspective view of the main part, FIG. 2 is a front view of the main part showing the sliding surface, and FIG. 3 is a main part front view showing the sliding surface. An explanatory diagram showing the frequency characteristics of the reproduction output of the thin-film magnetic head according to the present invention and the conventional single-film magnetic head. Figure 4 shows the magnetic domain structure when the core width is constant and the core film thickness and anisotropy constant are varied. An explanatory diagram showing appearance conditions. FIG. 5 is an explanatory diagram showing a layered circulating magnetic domain structure, and FIG. 6 is an explanatory diagram showing a planar circulating magnetic domain structure. 1...Lower magnetic core, 2...Upper magnetic core,
3. Substrate, 4... Insulating film, 5... Thin film coil, 6... Operating gap, 31... Magnetic flux propagation direction, 32a, 32b... Magnetization Direction, 33...
...Domain wall, W...Track width, T...
Total core thickness. 1st Figure 32 σ 5: i hard M) L 6: i busy motion setup 31: tsJ 臥東Iunoh 17! r phrase, 52a, 32b: Sekigu Ihi direction 33: Bansho 5 [Fig. 2 1 Fig. 3 @ JIAton] Exchange iMHz) No. 4 @ Layer thickness (&, is placed) Fig. 15 Fig. 6

Claims (1)

[Scope of Claims] 1. A magnetic head equipped with a magnetic core made of a magnetic metal thin film, characterized in that the magnetic domain structure of the magnetic core is a layered circulating magnetic domain structure at least in the working gap portion. head. 2. In claim 1, the film thickness of the magnetic core is T,
When the width of the magnetic core on the sliding surface is W, the exchange stiffness constant of the magnetic core is A, the magnetic anisotropy constant is Ku, and N is a natural number, the film thickness T of the magnetic core is T■2N(2W√[ A magnetic head characterized by a relationship of A/Ku])^1^/^2.