JPS5971123A - Thin film magnetic head - Google Patents

Abstract

PURPOSE:To obtain a thin film magnetic head having a high reproducing efficiency, by specifying the geometrical structure near an MR element, in the MR head foa a vertical magnetization signal reproduction having no width loss and thickness loss corresponding to gap loss. CONSTITUTION:The MR operation of the MR element 14 at a region 14 where the element 4 is overlapped partly on a permeability magnetic body 1 can not be expected, and the resistance change as the entire MR head 12 is decreased, then the electric efficiency is lower as the area of the overlapped part 14 is larger, and on the contrary, the magnetic efficiency is increased. Thus, this is opposite effect to each other. Then, the ratio of an area S1 of the overlapped part 14 to an area S2 of not overlapped area is taken as 0.1<S1/S2<0.6, thereby improving the reproducing efficiency.

Description

[Detailed description of the invention] Industrial applications The present invention is a two-page thin film magnetic spatula suitable for reproducing perpendicular magnetization. Regarding de.

Conventional Structures and Problems Perpendicular magnetic recording is known to be inherently more suitable for high-density recording than conventional longitudinal magnetic recording. However, there were still many problems during the regeneration process. for example,
When playing with a wound magnetic head using electromagnetic induction,
Single magnetic pole heads and ring heads have been proposed.

In the case of reproduction using a ring-shaped head, the gap length must be made extremely small in order to reproduce the short wavelength signal, which is a characteristic of perpendicular recording, and in this case, the efficiency of the magnetic circuit of the magnetic head becomes extremely poor. When the number of windings is increased in order to increase reproduction sensitivity, the self-resonant frequency decreases due to an increase in head inductance. On the other hand, since the signal frequency becomes higher as the recording wavelength becomes shorter, a decrease in the self-resonant frequency of the magnetic head is extremely inconvenient in signal reproduction. A single magnetic pole type head also has a similar problem because it is wound. A common and even bigger problem with electromagnetic induction heads is that when the relative speed between the head and the recording medium is small, the reproduction output voltage becomes small, and the countermeasure is to increase the number of windings, which solves the above problem. Enlarge. On the other hand, in a multi-track configuration in which a large number of magnetic heads are arranged in parallel, the winding space becomes a problem. moreover,
When constructed using thin film technology, the number of windings is limited, making it difficult to realize a highly sensitive reproducing head.

In order to solve these problems, recently the magnetoresistive effect (
(hereinafter abbreviated as MR) heads are attracting attention. A conventional MR head is, for example, a single-piece MR head in which a current is passed in the longitudinal direction of a strip-shaped MR element, the MR element is arranged perpendicularly to the recording medium, and the signal magnetic field is in the plane of the element at right angles to the longitudinal direction.
There is a head. It is known that in this type of MR head, the wavelength response caused only by the head structure is determined by the width of the MR element. In order to sufficiently reduce this wavelength loss, the element width W needs to be approximately the wavelength λ, which is extremely disadvantageous for heads oriented to short wavelengths. On the other hand, there is a shield type MR head in which a magnetic material with high magnetic permeability is arranged on both sides of the MR element in the thickness direction. It is known that this type of MR head exhibits substantially the same wavelength response as a conventional ring-shaped wire-wound head, and can be used at a considerably short wavelength and at high density. However, it is necessary to provide magnetic and electrical insulation between the MR element and the high permeability magnetic materials on both sides, and the insulation layer thickness G1. G2 corresponds to the gap length of a conventional ring-shaped winding head.

Furthermore, since the approximate form is the product of the gap loss of G1 and the gap loss of 02, in order to sufficiently reduce the gap loss at short wavelengths, it is necessary to make both G1 and G2 extremely small. It is extremely difficult to form a narrow gap length with no magnetic or electrical leakage.

In order to solve the above problems, the present inventor proposed the following thin film head. (Special application 1986-6273
No. 1) That is, N i -F e having electrodes at both ends,
A thin film head has a structure in which one end in the width direction of the MR element made of a ferromagnetic material such as N1-Co faces the recording medium, and the other end is magnetically coupled to one end of a permeable material that is in contact with the recording medium. M
It has the characteristic that the width loss caused by the RR element width is eliminated. To explain specifically using the drawings, as shown in FIGS. 1 and 2, a notch groove 2 is provided on the surface of an insulating magnetic substrate 1 such as ferrite, and a non-magnetic material 3 is placed in the notch. For example, a Ni--Fe alloy is deposited to a thickness of about 600 mm on a new surface filled with the same material and finished flush with the surface of the substrate 1, and then an electrode 6 is formed using a photolithography technique.
, 6 are arranged at both ends of the MRR element 4 in the longitudinal direction, and the MRR element 4 is provided parallel to the longitudinal direction of the notch groove 2. After that, M
In order to protect the R element, a protective film or a protective substrate 13 (not shown in FIG. 1) is provided.

The upper end of the MRR element 4 is magnetically coupled to the upper end 9 of the notched groove 2 provided in the magnetic substrate 1, and the lower end of the MRR element 4 is in contact with the recording medium 7. MRR element 4 of magnetic substrate 1
A surface 1o that is substantially perpendicular to this is a surface that comes into contact with the recording medium 7, and an arrow 8 is the direction of movement of the medium. Note that the dimension of the notch groove in the medium movement direction is 6 pages large so that it does not function as a gap for the ring head, and it also varies depending on the signal wavelength to be handled, so it is preferably 5 μm or more.

The above MR head uses base 1 as a recording medium.
By using a perpendicular two-layer film medium in which a soft magnetic layer 11 is interposed between the perpendicular magnetization film 7 and the perpendicular magnetization film 7, higher performance characteristics can be realized. That is, the magnetic flux generated from the signal magnetization recorded on the perpendicular recording medium 7 is guided from the lower end of the MRR element 4, and
The notch groove 2 in the board 1 passes through the RR element 4 and starts from its upper end.
through the substrate 1 to the contact surface 1 with the medium 7.
0, returns to the medium 7, passes through the soft magnetic layer 11, and passes through the MR
A closed magnetic circuit configuration returning to the lower end of the R element 4 is formed.

On the other hand, metal-deposited tapes have recently been actively developed as magnetic recording media, but when such conductive recording media are used, the structure in which the MR element is in contact with the medium as in the MR head described above cannot be achieved. Electrical leakage problems arise.

The inventor has developed a third head that can be used in such cases.
We proposed an MR head as shown in the figure. (Special application 1987-
62728) That is, the basic configuration and operating principle are the same as the MR head previously proposed in 71.-, but the MR element 4 is placed away from the medium, with one end facing the recording medium 7 and the other This configuration includes a magnetically permeable thin film 15 that is magnetically coupled to the MR element 4 and electrically insulated from the MR element 4. Fourth
The figure shows another embodiment in which an insulating film 17 made of a non-magnetic material is disposed between an MR element 4 and a magnetically permeable thin film 15.

The MR head proposed above is a magnetic head suitable for reproducing perpendicular magnetization, but the area where the MR element 4, the magnetically permeable body 1, and the magnetically permeable thin film 14 are magnetically coupled is adjusted to an appropriate range. If this is not done, the regeneration efficiency may drop significantly.

Purpose of the Invention The present invention provides an MR head for reproducing perpendicularly magnetized signals without thickness loss corresponding to width loss or gap loss, as described above, which achieves high reproduction efficiency by limiting the geometric structure near the MR element. The object of the present invention is to provide a thin film magnetic head having the following characteristics.

Structure of the Invention In the thin film magnetic head according to the present invention, one end of the magnetically permeable thin film including the MR element faces the recording medium side, the other end is magnetically coupled to the magnetically permeable body, and one end of the magnetically permeable body faces the recording medium side. The area of the part of the MR element that is arranged near the medium and is magnetically coupled to the magnetically permeable body is 81, and the part that is not magnetically coupled to the magnetically permeable body or other magnetically permeable thin film. The area of 8
2, 0.1〈S1/S2〈o, 6.

DESCRIPTION OF EMBODIMENTS In the case of an MR head with a structure as shown in FIGS. 1 and 2, the reproduction efficiency is determined not only by the efficiency of the magnetic circuit but also by
Since the MR element 4 partially overlaps the magnetically permeable body 1 in a plane and is magnetically coupled, MR operation cannot be expected in this overlapping region 14, and the electrical resistance change due to the small resistance change of the MR head as a whole There is an issue of efficiency. Naturally, this electrical efficiency decreases as the area of the shaped portion increases, but on the other hand, magnetic efficiency increases, which is a contradictory phenomenon, and the reproduction efficiency of the MR head 12 depends on both of these. Since it is in the form of a product, it is expected that the highest reproduction efficiency can be obtained by appropriately setting the ratio between the area of the molded portions 91 and the area of the entire MR element.

Figure 5 is a plot of the reproduction output of prototype MR heads with different molding amounts as described above versus the ratio of the area S1 of the overlapping part to the area S2 of the non-overlapping part, which is S1/52.
It can be seen that the maximum output is given around =0.3 to 0.4. The broken line in the figure is the result of approximate calculation, and the forward direction is seen to be in fairly good agreement. Since it is desirable for the head output variation to be within -3 dB in the system configuration, an MR head with high reproduction efficiency can be obtained by configuring the MR head within the range of o61<S1/S2<o,6.

In the case of an MR head having the structure shown in FIG. 4, in addition to the above-mentioned conditions, the MR element 4 and the magnetically permeable thin film 15 are
A similar phenomenon occurs in the overlapped portion 16 with . Figure 6 is M
This is a plot of the reproduction output of the MR head when the ratio of the area S3 of the overlapping part of the R element 4 and the magnetically permeable thin film 15 to 82 is changed, and the maximum output is obtained near S3/S2-〇, 3 on page 10. is given, −
If variation within 3 dB is allowed, o, 1〈S3/S2
<0.5 range. .

Effects of the Invention As described above, the thin film magnetic head of the present invention has no thickness loss corresponding to width loss or gap loss, and can reproduce high-density perpendicular magnetization signals with high reproduction efficiency.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a thin film magnetic head, FIG. 2 is a sectional view taken along lines A and A' in FIG. 1, FIG. 4 is a perspective view of another thin film magnetic head, and FIG. 5 and 6 are cross-sectional views showing other embodiments of the main parts of the same head shown in S1/S2. FIG. 6 is a diagram showing head output distribution when S3/S2 is changed. 1...Magnetic permeable material, 3...Nonmagnetic material, 4
...MR element, 7...Recording medium, 15
・・・・・・Magnetic permeable thin film. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] (1) One end of the magnetically permeable thin film containing the magnetoresistive element faces the recording medium, the other end is magnetically coupled to a magnetically permeable body, and one end of the magnetically permeable body is disposed near the recording medium. , the area of the part of the magnetoresistive element that is magnetically coupled with the magnetically permeable body is 81, and the area of the part that is not magnetically coupled with the magnetically permeable body or other magnetically permeable thin film is 82. A thin film magnetic head characterized in that, when 0.1<S1/S2<0.6. (Rumor: When the area of the part where the magnetoresistive element is magnetically coupled to another magnetically permeable thin film is 83, 0.1〈S3/
The thin film magnetic head according to claim 1, characterized in that S2<o,6.