JPH01184611A - Inductive thin film magnetic head - Google Patents

Abstract

PURPOSE:To take a stable magnetic domain structure, to reduce a waveform distortion and to increase a reproducing output by constituting the plane form of a magnetic core so as to have the angle of about 90 deg. formed by the end of a magnetic pole and a back core. CONSTITUTION:The plane form of the magnetic core is constituted so as to have the angle of about 90 deg. formed by the end P of the magnetic pole and the back core B. In such a way, the magnetic domain structure of the magnetic core is a magnetically stable circulating magnetic domain structure. The magnetic domain structure indicating a magnetic domain wall by the heavy line in the drawing is obtained by a bittering method. In the vicinity of the boundary of the end P of this magnetic pole and a back area B, a stable 180 deg. magnetic wall W substantially parallel to a medium is formed and an unstable triangular magnetic domain S is formed at a part remote from the end part, so that the stable magnetic domain structure is formed as a whole. Thereby, a magnetization is a simple operation to reduce the waveform distortion and increase the reproducing output.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a magnetic head for writing and reading information to and from a recording medium in a magnetic recording device, and particularly relates to a thin film magnetic head suitable for high-density magnetic recording. It is related to.

[Conventional technology]

In general, a thin film magnetic head consists of a magnetic core made of a magnetic thin film having a yoke structure and a conductive layer coil sandwiched between the magnetic core, and a magnetic pole portion P at the tip of the core faces the medium for recording and reproducing. Regarding the shape of the magnetic core, see JP-A-54
As described in No. 144501, the rear core B is designed to have as wide a cross-sectional area as possible for the purpose of increasing recording and reproducing efficiency and preventing magnetic saturation. As shown in FIG. 3, with respect to the rectangular magnetic pole tip P having a width approximately equal to the track width X facing the medium, the planar shape of the magnetic film of the rear core portion B that covers the upper and lower portions of the coil gradually changes. It is designed to be expansive. Further, the upper magnetic layer is depressed at the 0 part and has a structure in which it contacts the lower magnetic layer.

[Problem that the invention seeks to solve]

This conventional technology does not take into consideration the behavior of magnetization that occurs within the magnetic core during head operation, and the magnetic domain structure generated in the core is uneven and unstable, and the magnetization behaves in multiple ways, resulting in a reproduction output. There was a problem in that it caused a decrease in signal strength and waveform distortion. In particular, the magnetic domain structure at the boundary between the magnetic pole tip and the rear core that extends from there is most unstable due to the influence of shape and magnetostriction, and has a large effect on both recording characteristics. The objective is to design a magnetic core shape that has a magnetically stable magnetic structure and whose magnetization behaves simply during head operation.

[Means for solving problems]

The above object is achieved by making the planar shape of the rear core such that the angle θ it makes with the tip of the magnetic pole is approximately 90″, preferably in the range of 80° to 90°.

[Effect]

The magnetic domain structure of the magnetic core is in a second magnetically stable state.
The thick lines in the diagram indicate the domain walls, and such a magnetic domain structure is obtained by the Bitter method or the Kerr effect observation device, as shown in the diagram, where the magnetic pole tip and rear part are formed. In the vicinity of the boundary with the region, a stable 180@ domain wall W is formed along the outer shape with an angle of approximately 90° with the tip region, that is, approximately parallel to the medium, and an unstable triangular magnetic domain S is formed in a portion far from the tip. This results in an overall stable magnetic domain structure. As a result, magnetization does not behave in a complicated manner, suppressing waveform distortion and increasing reproduction output.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a plan view of a thin film magnetic head showing one embodiment of the present invention. 10 is a magnetic core obtained by patterning a magnetic film of permalloy, amorphous, etc. formed on a substrate by sputtering or the like using ion milling or the like using a photoresist as a mask, and 20 is a conductor coil. In this example, the upper and lower magnetic layers have approximately the same size, and the upper and lower magnetic layers of the magnetic core are in contact at C to form a yoke structure, and the conductor fill 20 is provided in this space.

Insulated by an insulating layer. FIG. 2 shows the magnetic core 10 of FIG. 1. In this example, the magnetic pole is made of permalloy alloy, and its planar shape is such that the angle θ between the magnetic pole tip and the rear region is 90''.The dimensions of the magnetic core are Q
, = 100 pm, and Q2 = 80 μm.

The magnetic domain structure of the magnetic core is a uniform reflux magnetic domain structure as shown in FIG. 2, and the magnetization does not behave in a complicated manner, suppressing waveform distortion and increasing reproduction output.

When recording and reproduction was performed using a γ-Fe203 coated medium with a film thickness of 0.4 μm and a spacing of 0.3 μm, the reproduction output in the high recording density region (20 kPCI) was as high as that of the conventional core shape shown in Figure 3. This was approximately 20% higher than the thin-film head, and it was possible to further reduce waveform distortion. Angle θ is 8
A similar effect was seen in the range of 0 to 90 degrees, but when θ was changed to 8
When the angle was made smaller than 0 degrees, waveform distortion increased rapidly. This is because a triangular magnetic domain is generated in the vicinity of the tip and rear core connection portion.

FIGS. 4 and 5 show other embodiments. Figure 4 shows the planar shape of a magnetic core in which the angle between the magnetic pole tip and the rear region is 90°, and the rear region has a portion parallel to the medium, and then has a gradually wider force angle in the perpendicular direction. . Also, since the magnetic domain structure at the boundary between the tip region and the rear region is stable and the magnetization does not exhibit multiple behaviors, waveform distortion is suppressed and the output is increased.

As a result of experiments conducted by changing the length Q3 of the side facing parallel to the medium, it was found that the effect is greatest when j23 is equal to or greater than the track width.

FIG. 5 shows a planar shape of a magnetic core in which the planar shape of the rear region is a rectangle with a convex region at the rear end, and the contact portion C between the upper magnetic layer and the lower magnetic layer is within the aforementioned convex region T. This not only has a stable magnetic domain structure at the boundary between the tip region and the rear region, but also has a stable magnetic domain structure throughout the rear core except for the convex region, which results in even better effects of the present invention and waveform distortion. can be completely suppressed and increase output.

The frequency of occurrence of waveform distortion (wiggle) in the thin film magnetic head having the magnetic pole shape shown in FIG. 5 was investigated by performing recording and reproduction using a disk device using a γFe2O3 coated disk at a flying height of 0.3 μm. Measurements were performed under various external conditions such as varying the external magnetic field, but no waveform distortion that would lead to errors in the disk device was observed. On the other hand, in the conventional thin film magnetic head shown in FIG. 3, when recording and reproducing were performed 100 times, waveform distortion resulting in errors occurred 38 times. In addition, in the head having the magnetic pole shape shown in FIG. 4 according to the present invention, waveform distortion was observed three times in 100 recording and reproducing operations, but all of these distortions can be corrected and do not pose a practical problem.

When the range of the present invention is exceeded, waveform distortion increases rapidly.

The effects of the present invention can be applied to general cases, but are particularly noticeable when the track width becomes narrow.

When the track width is 20 .mu.m, even the conventional magnetic pole shape does not cause any major problem because the output is originally large, but when the track width is 15 .mu.m or less, the effect of the present invention becomes remarkable.

(Effects of the Invention) According to the present invention, the reproduction output of the thin film magnetic head can be increased and the waveform distortion can be reduced, thereby improving the performance of the magnetic storage device.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an inductive thin film magnetic head according to an embodiment of the present invention, FIG. 2 is an enlarged plan view of the magnetic core shown in FIG. 1, and FIG. 3 is an example of a conventional magnetic core. FIGS. 4 and 5 are plan views of magnetic cores showing other embodiments of the present invention. 10... Magnetic core magnetic film, 20... Conductor coil, P
...Magnetic pole tip region, B...rear region, C...upper and lower magnetic film contact area, T...convex region. Multi 7 times 12 times 14 times ￥J's! 45 times

Claims (1)

[Claims] 1. Inductive thin film magnetism having a magnetic core consisting of a rectangular magnetic pole tip with a width approximately equal to the track width facing the magnetic medium and a rear core with a cross-sectional area wider than the cross-sectional area of the magnetic pole tip. An inductive thin film magnetic head characterized in that the planar shape of the magnetic core is such that the angle between the tip of the magnetic pole and the rear core is about 90°. 2. An inductive thin film magnetic head according to claim 1, wherein the length of the side of the rear magnetic core that faces substantially parallel to the medium is longer than the track width. 3. Scope of Claims The head according to claim 1, wherein the planar shape of the rear region has a convex region at the rear end,
An inductive thin film magnetic head characterized in that a contact portion between an upper magnetic layer and a lower magnetic layer has a magnetic core located within the convex region.