JPS61158017A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To obtain the titled thin film magnetic head having high electromagnetic transducing efficiency and reliability by providing plural grooves to both the upper and the lower pole piece, and directing the grooves in almost the same direction as the easy magnetization axes of the pole pieces. CONSTITUTION:Rugged grooves are provided to both the upper and the lower pole piece 6 and 3 and insulating layer 2 and 4 used as the substrates. The magnetic anisotropy of a CoZr film is controlled so that the grooves may be directed in almost the same direction as the easy magnetization axis of the Co90Zr10 film constituting the lower pole piece 3. Consequently, the deterioration of magnetic permeability is remarkably controlled even in the amorphous CoZr soft magnetic material whose aged deterioration is known to be remarkable, the deterioration in the magnetic characteristics of both the upper and the lower pole piece constituting the magnetic circuit which controls considerably the electromagnetic transducing efficiency of the magnetic head is reduced, and high electromagnetic transducing efficiency and reliability can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic head, and more particularly to an inductive thin film magnetic head used in magnetic disk devices, magnetic tape devices, etc.

(Prior art and its problems) As is well known, in the recent field of magnetic deployment.

As recording densities continue to increase, magnetic recording media with high coercive force are being researched and developed. Reflecting this situation, the magnetic circuits of magnetic heads, which support magnetic recording technology as well as deployment media, are being improved. Excellent magnetic properties and high reliability are required for the soft magnetic materials that make up the pole pieces.

Generally, in an intactive thin film magnetic head,
When writing information, the head drive current flowing through the coil generates heat, and due to this heat, the ball pieces that make up the magnetic circuit of the thin film magnetic head are constantly subjected to heat cycles of heating and cooling. The magnetic domain structure within the pole piece is disrupted, and magnetic anisotropy with a different direction locally appears, the magnetic permeability decreases significantly, the initial excellent magnetic properties deteriorate, and the electromagnetic conversion efficiency of the thin-film magnetic head decreases. In particular, with amorphous soft magnetic materials that are being used in place of conventional crystalline soft magnetic materials such as NiFe alloys, the amorphous material itself has the problem of However, there was a problem in that the magnetic properties were thermally unstable and their magnetic properties changed over time, further accelerating the deterioration of the properties due to the heat cycle described above.

Therefore, is the pole piece material crystalline?

Regardless of whether it is amorphous or not, suppressing changes in magnetic properties over time has been an extremely important problem.

(Object of the Invention) In view of the above points, an object of the present invention is to eliminate the above-mentioned conventional drawbacks and realize a thin-film magnetic head with high electromagnetic conversion efficiency and reliability. According to the present invention, a coil made of a conductive material and an absolute wire layer made of an insulating material are sandwiched between upper and lower pole pieces constituting a magnetic circuit made of a soft magnetic material. In the thin film magnetic head, at least one of the upper and lower pole pieces has a plurality of grooves, and the direction of the grooves and the easy axis of magnetization of the pole piece having the grooves are substantially the same direction. (Detailed explanation of the structure) The present invention provides a thin-film magnetic head characterized by the above-mentioned structure, which makes it possible to provide a thin-film magnetic head that improves the conventional problems. By forming uneven grooves in the insulating layer that serves as the base of at least one of the side pole pieces, and laminating a soft magnetic thin film on top of the insulating layer to form the pole piece, the uneven grooves can be formed. B. Stabilizes the magnetization state of the soft magnetic thin film, prevents the appearance of locally oriented magnetic anisotropy in the upper and lower pole peels, and deteriorates magnetic properties, especially decreases in magnetic permeability. and has excellent electromagnetic conversion efficiency. A highly reliable thin film magnetic head is realized (Example) An example of the present invention will be described below with reference to the drawings. 1st
Figure (a) is a schematic cross-sectional view showing an example of the structure of a thin film magnetic head according to the present invention. Figure 1 (at k120B
- KLVOSK is formed as an insulating layer 2 on a substrate l made of Tic ceramics, and amorphous Cogo Zr with a film thickness of 2 μm is further formed on the insulating layer 2 using integrated thin film technology. (Weight ratio) Upper and lower pole pieces 6 and 3 made of a soft magnetic material are formed, and a coil 5 made of Cu is placed between the pole pieces 3 and 6, and a heat exchanger serving as a magnetic gap or step elimination layer is placed between the pole pieces 3 and 6. It has a structure in which an insulating layer 4 made of a hardened organic material is sandwiched therebetween. Here, the upper and lower pole pieces 6.3 and the underlying insulating layers 2 and 4 have uneven grooves.

That is, for example, in the case of the lower pole piece 3,
FIG. 1 [Substrate 1 in at. Insulating layer 2. Lower pole piece 3
As shown in FIG. 1(b), which is an enlarged view of the part shown in FIG. A plurality of grooves are formed, and the lower pole piece 3 is formed thereon by a sputtering method or the like. Here, the direction of the groove and the lower pole piece 3 are
The magnetic anisotropy of the CoZr film is controlled so that the axis of easy magnetization of the t-forming COgoZr10 film is approximately in the same direction (perpendicular to the plane of the paper in FIG. 1(b)).

FIG. 2 shows changes in magnetic permeability over time between the thin film magnetic head according to the present invention and a conventional head, that is, a head having the same structure as the head according to the present invention except that the pole piece does not have a groove. In FIG. 2, the solid line shows the case of the thin film magnetic head according to the present invention, and the broken line shows the case of the conventional thin film magnetic head. Here, the horizontal axis shows the processing time left in the atmosphere at 80°C on a logarithmic scale, and the vertical axis shows the magnetic permeability μ0 before treatment and the magnetic permeability μ(t
It is normalized and shown by l.

In addition, the measurement of magnetic permeability is carried out by Review Op Scientia I.
Tsuku Instrument Magazine (Review of Sci
Entific Lnstruments) No. 46
Volume (1975) e page 904, that is, when a test sample is inserted into the lower part of a thin film coil formed in a figure 8 shape and the test sample is excited by another coil for applying a magnetic field, The magnetic permeability was determined by calculating the magnetic permeability from the ratio of the magnetic flux density determined by the amount of magnetic flux interlinking to the figure-8 coil and the excitation magnetic field. Further, the measurement frequency of magnetic permeability is I MHz.

As shown in FIG. 2, in the thin film magnetic head according to the present invention, the change in magnetic permeability over time is suppressed compared to the conventional thin film magnetic head, that is, a head without uneven grooves on the pole piece. for example.

Even after 1000 hours, the magnetic permeability is about 90% of the initial value. On the other hand, in conventional heads, the initial value is approximately 6.
5- also shows a decrease in magnetic permeability and a large change over time.

As described above, since the pole piece has the uneven grooves, the thin film magnetic head according to the present invention can reduce the magnetic permeability even in the amorphous CoZr soft magnetic material, which is known to have a large change over time. The deterioration of the magnetic properties of the lower pole piece, which constitutes the magnetic circuit that greatly influences the electromagnetic conversion efficiency of the magnetic head, is reduced.
High electromagnetic conversion efficiency and high reliability are achieved.The soft magnetic material forming the pole piece is not limited to the amorphous CoZr soft magnetic material, but may also be made of other materials such as C.
oTaZr, CoZrNb, CoTa, C
oNb.

CoHf, CoHfNb? CoNbTiF
Amorphous soft magnetic materials such as e-Co-8i-B or N
It goes without saying that crystalline soft magnetic materials such as iFe-based alloys, re-8i-based alloys, and re-N-based alloys may also be used. Furthermore, materials other than those in the examples can be used for the insulating layers 2, 4 and the coil 5. Furthermore, the shape of the uneven groove formed in the pole piece, the width W (pitch 2W) and the depth d of the tab should be determined according to the type of soft magnetic material forming the pole piece, the film thickness, magnetic properties, etc. Of course, this does not define the present invention.

Furthermore, although the above embodiment shows a configuration in which grooves are formed in both the upper and lower pole pieces, even if grooves are formed in either pole piece, the decrease in magnetic permeability is extremely small compared to conventional thin-film magnetic heads. 90 (Effects of the Invention) As stated above, in the thin film magnetic head according to the present invention, in addition to forming the magnetic circuit, the magnetic properties of the soft magnetic material that constitutes at least one of the lower pole pieces, such as magnetic permeability. A thin film magnetic head with high electromagnetic conversion efficiency and high reliability is realized.

[Brief explanation of the drawing]

FIG. 1 (at is a cross-sectional view showing the structure of a thin film magnetic head according to the present invention, FIG. 1(b) is an enlarged view of FIG. 1(a), and FIG. 2 is a graph showing changes in magnetic permeability over time. In the figure, 1...substrate, 2, 4... insulating layer, 3...
...lower pole piece, 5...coil, 6...mouth which is the upper pole piece

Claims (1)

[Claims] In a thin film magnetic head comprising a coil made of a conductive material and an insulating layer made of an insulating material sandwiched between upper and lower pole pieces made of a soft magnetic material constituting a magnetic circuit, at least one of the upper and lower pole pieces A thin film magnetic head having a plurality of grooves on one side, and the direction of the grooves and the easy axis of magnetization of the pole piece having the grooves are substantially the same direction.