JPS5922216A - Magneto-resistance effect type magnetic head - Google Patents

Abstract

PURPOSE:To simplify a process and to improve yield by arranging magneto- resistance (MR) elements close to a part of magnetic yorks, generating magnetic coupling between the magnetic york and the MR element and changing the electric resistance of the MR element to obtain a reproduced signal. CONSTITUTION:The magnetic flux 38 of a magnetic signal and magnetic flux 36 projected from the MR element interact each other, and as the result, the anti-magnetic field of the MR element is changed and the magnetized direction 35 in the MR element is changed and read out as a signal. In the figure A, the MR element is formed only on one side of the yorks 18, 19, but the same effect appears at the formation of the MR elements on both sides. The same effect is also observed in case of forming the MR elements on both right and left end surfaces of the yorks 18, 19. Although a current course shown in the figure B is prepared for the MR element, it is also available to wind a wire around the MR element as the ordinary method and make faint current flow into the winding to form a bias magnetic field.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetoresistive magnetic head, and more particularly to a magnetoresistive magnetic head with improved corrosion resistance and wear resistance.

In response to demands for high-density magnetic recording, various improvements have been made to magnetic heads.

There are two main types of improvements.One is that the structure is the same as the conventional ring-shaped magnetic head, but the gap formation method, winding position, external dimensions, etc. have been improved. One method is to improve the magnetic field by using a Hall element or a magnetoresistive element as a magnetoresistive element.

Of these two methods, magnetoresistive magnetic heads made of ferromagnetic thin films are suitable for high-density magnetic recording, and can be manufactured using the so-called thin film deposition method.
It is suitable for mass production and is attracting wide attention.

A magnetoresistive element has a property that its electrical resistance changes when an external magnetic field approaches while a constant current is applied thereto, and a magnetic signal is detected based on this change in electrical resistance.

FIG. 1 shows a general structure of a magnetoresistive magnetic head (hereinafter referred to as MR head) using a conventional magnetoresistive element (hereinafter referred to as MR element) of this type.

In FIG. 1, the reference numeral 1 indicates a substrate, which is white.

Conductive layers 2, 2 are formed on the side surfaces of this substrate 1. The conductive layers 2, 2 are made of M+ metal such as Cu or Au with a thickness of 1 μm.
It is molded with a film thickness of 8 degrees, and serves as an electrode for supplying current to the MR element.

On the other hand, what is indicated by the reference numeral 3 is an MR element, which is formed on the side surface closer to the magnetic recording medium sliding surface 6 side.

This MRR element 3 is made of a ferromagnetic alloy thin film of Ni--Fe or Co--Ni alloy with a thickness of about 0.05 .mu.m. When the signal magnetic field is weak, for example when the magnetic field strength is 100e or less, Ni-Fe is suitable as the detection element material.

In the case of the example shown in FIG. 1, the thin film of the MRR element 3 is the conductive layer 2.
, 2, but this is caused by omitting the removal process to shorten the manufacturing process, and has no function for signal reproduction.

The reference numeral 4 designates a permanent magnet, which is used as a magnetic field generation source for applying a bias magnetic field to the MR Hijiko 3, as will be described later.

Further, the reference numeral 5 indicates a protective plate, which is often made of the same material as the substrate 1 or transparent glass. After forming the conductive layer 2 and the MRR element 3 on the substrate 1, this protective plate 5 is bonded to the magnetic recording medium sliding surface 6 with an adhesive.
, 6. This sliding surface polishing is an extremely important step in determining the stripe width W of the MRR element 3 and in reducing spacing loss due to warping.

By the way, 7 shown as a male diagram in FIG. 1 is a coordinate system for clarifying the directions of each member in FIG. 1 and aiding understanding. The X-axis direction is the track width direction and the direction of the current flowing through the MRR element 3. and coincides with the easy axis direction of magnetization. The y-axis direction indicates the running direction of the magnetic recording medium, and the Z-axis direction indicates the direction of the magnetic field component that contributes to a change in the electrical resistance of the MRR element 3 in the signal magnetic field emitted from the magnetic recording medium.

Here, the signal magnetic field and the change in electrical resistance of the MR element will be explained with reference to FIG. 2 (5). In Figure 2 (5),
The same parts as in FIG. 1 or corresponding parts are given the same reference numerals, and the explanation thereof will be omitted.

In FIG. 2(5), the reference numeral 8 indicates a power source, and the direction of the current supplied by this power source is indicated by the arrow 9. 1, the dotted line indicated by the arrow IO is the easy axis direction of magnetization of the MRR element 3, which coincides with the X-axis direction shown as a male diagram in FIG. 2(A).

Reference numeral 11 indicates the direction of a signal magnetic field leaking from the magnetic recording medium, and is applied to the MRR element 3 in parallel to the Z-axis direction. Assuming that the magnetization direction M of the MRR element 3 when this signal magnetic field is applied has an inclination of θ with respect to the X-axis direction, as shown by the arrow 12 in the figure, the resistance value R of the MRR element 3 is Assuming that the minimum resistance of No. 3 is R6 and the resistance change width is ΔR, it is expressed by the following equation (1).

R=R6+ΔRcos2θ ・Convex curve...(+)
When the above-mentioned equation (1) is graphed, it becomes a curve indicated by reference numeral 13 in FIG. 2(B).

On the other hand, the anisotropic magnetic field HK of the MRR element 3 and the demagnetizing field H due to the magnetization M of the MR element shown in FIG.
d (Assuming that this direction is indicated by reference numeral 14 in FIG. 2(g)), the direction θ of magnetization M is expressed by the following equation (2).

The demagnetizing field Hd mentioned above is the stripe width W of the MR element 3,
Using the thickness T, it can be expressed by the following equation (3).

This demagnetizing field Hd changes depending on the direction of magnetization M.

The effect of this is shown in the area indicated by diagonal lines 15 in FIG. 2 (03). That is, as the direction of magnetization M becomes biaxial, the sensitivity of the MR element 3 decreases.

On the other hand, as the stripe width W becomes smaller, the demagnetizing field increases and the sensitivity decreases. This was mentioned above.

As a result of equation (1), the positive and negative signs of the signal magnetic field direction H3 are different, and the resistance change is the same for signals with the same absolute value, and the resistance change is the same for signals with the same absolute value. It can be seen that a reproduced signal can be obtained.

To correct this and improve linearity, a magnetic field Hn is applied. This bias magnetic field Hn is shown in Figure 2 (3
) is indicated by an arrow 17.

This bias magnetic field Hn is as shown in FIG.
This means moving the operating point of the R element to the most sensitive part of the element.

By the way, when reproducing a magnetic signal using the MR head having the above-described structure, unless a stripe width W of at least five times the wavelength λ to be reproduced is provided, the reproduced signal voltage will be extremely reduced. It has been known.

Now, when considering a wavelength of 0.6 μm, the stripe width is 3 μm. This value not only makes it extremely difficult to form the stripe width by polishing, but also causes an increase in the demagnetizing field and the bias magnetic field, which erases the signals recorded on the magnetic recording medium. This is an inconvenient phenomenon that occurs.

Then, it becomes 1700e from equation (3).

Generally, it is said that the bias magnetic field requires 1 to 3 times the demagnetizing field, and in the above case, the magnetic field is 170 to 5000 e. When such a large magnetic field is applied to the MR element, the same degree of magnetic field is also applied to the magnetic recording medium placed very close to the MR element, and there is a possibility that the magnetization signal will be erased.

Furthermore, since the MR element 3 of the conventional MR head is exposed on the sliding surface of the magnetic recording medium, it is easily corroded by the outside air and lacks durability. Furthermore, when this MR head is used as a magnetic head for a VTR,
The relative speed between the magnetic recording medium and the reproducing head is high, and the amount of wear per hour is large, with a speed of 3 μm! - It was difficult to guarantee the operating time (usually about 1000 hours) with the live width.

The shortcomings of the conventionally structured MR head described above can be summarized as follows.

(1) Processing is difficult because the stripe width is extremely narrow.

(2) Since the stripe width is reduced by 11\, the required bias magnetic field becomes extremely large, causing the inconvenience that the applied bias magnetic field erases the magnetic signal of the magnetic recording medium.

(3) Since the MR element was exposed to the outside air, there was a problem in corrosion resistance.

(4) The stripe width was narrow and there were insufficient measures against abrasion, resulting in poor durability.

(5) Since the stripe width was narrow, the sensitivity of the MR element was significantly reduced.

SUMMARY OF THE INVENTION An object of the present invention is to provide an MR head that eliminates the above-described drawbacks of the conventional MR head, simplifies the manufacturing process, improves yield, and reduces noise.

In the present invention, in order to achieve the above object, MR
A structure in which the element is placed close to a part of the magnetic yoke of a magnetic head using an MR element, and the electric resistance of the MR element is changed by magnetic coupling between the magnetic yoke and the MR element, thereby making it possible to obtain a reproduced signal. It was adopted.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 3 (5), [F]) explains one embodiment of the present invention. In FIG. In the example shown in 6), the shape is the same as the conventional one, but it is shown without winding. Reference numeral 20 indicates a magnetic gap.

Further, numerals 21 to 26 indicate MR elements. The width of this element need not be limited to 3 μm as described above, but is selected so as to obtain a desired resistance value.

Reference numerals 27 to 32 indicate electrodes, and MR elements 21 to 2
Care is taken so that the azimuth relationship between the current flowing through the magnetic head 6 and the magnetic field passing through the MR head is constant.

Further, the reference numeral 33 is a terminal for passing a current through the MR elements 21 to 26 and extracting a signal.

Although the MR elements 21 to 26 are connected in series in FIG. 3(G), they may be connected in series or connected as needed.
Parallel and non-coupled connection states may be mixed.

Next, the fact that a magnetic signal can be detected by the structure shown in FIG. 3 (A>) will be explained using FIG. 3 ([3)].

In FIG. 3 [F]), FIG. 3 (3) is a partially enlarged sectional view taken along the line A-A.

In Fig. 3 03), the reference numeral 34 is an insulating layer;
It is formed from a vapor-deposited film of 5i02 or a thin film formed by a chemical vapor deposition (CVD) method. The arrow designated by numeral 35 indicates the magnetization direction of the MR element, and the magnetic flux emanating from this is designated by numeral 36. This magnetic flux 3
6 passes through the yoke 19 to form a closed loop according to the principle of minimum magnetic energy. This state is called magnetic coupling.

In addition, in Figure 3 (B), the one indicated by the symbol 37 is the third
This is a current path formed of a thin film for applying an appropriate bias magnetic field to the MR element (not shown in FIG. 3), and replaces the permanent magnet 4 shown in FIG. 1. The notch of this current path almost matches the shape of the MR element and the electrode, and is formed with an insulating layer 37a interposed therebetween.

Further, reference numeral 38 indicates magnetic flux due to the signal magnetic field entering from the gap 20.

In the state shown in FIG. 3 (0), most of the magnetic flux that provides a demagnetizing field to the MR element is absorbed within the yoke due to the above-mentioned magnetic coupling, and the demagnetizing field becomes less than one-tenth of that of the conventional structure. Moreover, since the stripe width can be set relatively large, the demagnetizing field can actually be lowered by 2 to 30 e.
It becomes.

Therefore, if the width of the current path is 10 μm (approximately the same as the stripe width), a current of 10 to 30 mA is sufficient for the current path. In addition, in FIG. 3(B), the magnetic flux of the bias magnetic field due to the current path 37 is omitted.

Based on this structure, the magnetic flux 38 of the magnetic signal and the magnetic flux 36 emitted from the MR element interact within the yoke, and as a result, the demagnetizing field of the MR element changes, and the magnetization direction 35 within the MR element changes. It can be changed and read out as a signal.

Further, in FIG. 3(3), the MR element is formed only on one side of the yokes 18 and 19, but the same effect can be obtained even if the MR element is formed on both sides. Further, the same effect can be obtained by forming the grooves on the left and right end surfaces of the yokes 18 and 19.

Furthermore, although the current path 37 shown in FIG. 3(B) is provided for the MR element, it is wound in the conventional manner.
This is possible by passing a small current through this winding to create a bias magnetic field.

Since this embodiment is configured as described above, the drawbacks that conventionally occurred due to narrowing the stripe width are eliminated.
There are no problems with wear resistance and durability because the structure of the yoke is the same as the conventional structure.

1. Since it is possible to easily adopt a structure in which the MR elements 21 to 26 are not directly exposed to the outside air, there is no problem with corrosion resistance.

Furthermore, the piano winding (current path) and the recording winding (current path) can be the same, making it possible to take advantage of the characteristics of reproduction by an MR head, that is, to perform magnetic recording and reproduction based on magnetic flux response.

Furthermore, since the magnetization of the MR element is stabilized by magnetic coupling, the noise is reduced, the S/N ratio of the signal is improved, and a remarkable effect is obtained for low-frequency magnetic signals of 100 melt or less. It will be done.

FIG. 4 explains another embodiment of the present invention, and this embodiment is exemplified as a writing thin film magnetic head.

In the figure, the reference numeral 39 is a magnetic substrate (magnetic yoke) made of Mn--Zn ferrite, Ni--Zn ferrite, etc., and an insulating layer 40 is formed on its side surface. This insulating layer 40 also serves as a spacer for forming a head gap 41'. An electrode 42 is formed on the outer surface of the insulating layer 40, and serves as both a write current path and a bias magnetic field current path.

An insulating layer 43 is formed on the outside of the electrode 42, an MR element 44 is formed on the outside of the insulating layer 43, and another insulating layer 45 is formed on the outside of the MR element 44. An upper magnetic layer 46 is formed outside the insulating layer 45. 5in2 or SiO is suitable for the insulating layers 43 and 45.

A night retaining plate 48 is bonded to the outside of the MR element 46 via an adhesive layer 47 made of water glass, low melting point glass, epoxy resin, or the like. The reference numeral 49 is a magnetic recording medium sliding surface.

Even if such a structure is adopted, M
Magnetic coupling occurs between the R element 44 and the upper magnetic layer 46, and an appropriate bias magnetic field is applied by the weight 42, making it possible to detect the signal magnetic flux passing through the upper magnetic layer 46.

As a result, in addition to the effects similar to those shown in FIG. 3 being obtained, there is also the effect that a multi-I rack recording/reproducing head can be easily obtained.

In the embodiment shown in FIG. 4, the MR element 44 is provided between the substrate 39 and the upper magnetic layer 46, but it may be provided between the protective plate 48 and the upper magnetic layer 46. An example employing such a structure is shown in FIG.

In the embodiment shown in FIG. 5, an insulating layer 50 is formed above the upper magnetic layer 46, and MR elements 51 to 54 are formed in a plurality of stages outside the insulating layer 50. The reference numeral 55 indicates a current path for applying a bias magnetic field.

If such a structure is adopted, a plurality of MR elements can be arranged in a row, and a large signal output can be obtained.

FIG. 6 illustrates another embodiment of the present invention,
This is an example of a magnetic head for perpendicular magnetic recording.

In the figure, the reference numeral 56 indicates an auxiliary magnetic pole, around which a coil 57 is wound. This auxiliary magnetic pole 56 and the magnetic recording medium 5
A main magnetic pole 59 is arranged with the main magnetic pole 8 in between. This main magnetic pole 5
9 is provided with an MR element 61 via an insulating layer 60, and further provided with a current path 63 for a bias magnetic field via an insulating layer 62. The MR element 61 is provided at a position where it will not be affected even if the main magnetic pole 59 wears out.

Note that the magnetic recording medium 58 has N 1 on the base film 64.
A layer of a high permeability magnetic thin film 65 made of a -Fe alloy thin film or the like is formed, and a recording layer 66 is formed on the outside thereof. This recording layer 66 is a layer with vertical 611 anisotropy, and has a thickness of 1 μm.
Generally, a Co--Cr film of about 100% is used.

On top of this, if the 111 structure is adopted, the main magnetic pole 59 and MR
Magnetic coupling occurs between the main magnetic pole and the main magnetic pole, and the MR element 61 can detect a change in magnetic flux passing through the main pole as a change in resistance.

Note that the perpendicular magnetic recording method is attracting attention because it can perform high-density recording with a recording wavelength of about λ-02 μm in the running direction of the magnetic recording medium, but the perpendicular magnetic recording method is attracting attention because it can perform high-density recording with a recording wavelength of about λ-02 μm in the running direction of the magnetic recording medium. In many cases, a constant output can be obtained regardless of the read speed, making it extremely effective as an intermediate memory.

As is clear from the above description, according to the present invention, the MR element is provided close to a part of the magnetic yoke, magnetic coupling is caused between the magnetic yoke and the MR element, and the electrical resistance of the MR element is Since a configuration is adopted in which a reproduced signal is obtained by changing the , it is possible to simplify the manufacturing process, improve yield, and obtain an MR head with reduced noise.

[Brief explanation of drawings]

Figure 1 is a partially enlarged exploded perspective view explaining the conventional structure;
Figure (G) is an explanatory diagram of the operating principle of the MR element, Figure 2 (B)
3 (6) is a front view showing an embodiment of the present invention, and (5) in FIG. 3 is a diagram showing the output characteristics of the MR element.
4 to 6 are partially enlarged side views showing different embodiments of the present invention. 18.19...Magnetic yoke 20...Gap 2
1-26...MR element 27-32...electrode 3
4...Magnetic layer 37...Current path Figure 3 Figure M4 Figure 5 Procedural amendment (spontaneous) October 8, 1980 Mr. Commissioner of the Japan Patent Office 1, Indication of the case 1982 Patent Application No. 131133 2,
Name of the invention: Magnetoresistive magnetic head 3, relationship with the case of person making corrections Name of patent applicant (100) Canon Corporation 4
, agent telephone 03 (268) 2481
(Contents of the amendment (1) The scope of claims is amended as shown in the attached sheet in Column 6 of Detailed Description of the Invention in the Specification, Contents of the Amendment as shown in the attached sheet. (2) Line 7 of page 3 of the specification Correct “recording” to “recording and playback”. (3) Correct rHKJ on page 6, line 17 to “H”. (4) Formula (2) on page 7, line 2 rH3J of rH
Correct to s J. (5) "rHs" on page 7, line 20 of the same page rHs J
Correct. (6) On page 8, line 12, "5 times or more" is corrected to "5 times or less." (7) "Same shape" on page 11, line 9 is corrected to "same ring-shaped magnetic core." (8) "rMR element 46" on page 16, line 3
The upper magnetic layer 46J is corrected. (8) Change "intermediate memory" on page 18, line 14 to "
Correct to "memory". The scope of patent claims will be amended as follows. (1) By providing a magnetoresistive element close to a part of the magnetic yoke and magnetically coupling the magnetic yoke and the magnetoresistive element, the electric resistance of the magnetoresistive element is changed to obtain a reproduction signal. A magnetoresistive magnetic head characterized by being configured as follows. (2) A magnetoresistive magnetic head according to claim 1, wherein the magnetic yoke is a 6-magnetic core. (3) The magnetoresistive effect according to claim 1, characterized in that the magnetic yoke is one part of a thin film magnetic head, and the setting position of the magnetoresistive element is provided close to the current path. type magnetic head. (4) A magnetoresistive magnetic head according to claim 3, wherein the magnetoresistive element is covered with a magnetic layer. (5) A magnetoresistive magnetic head according to claim 1, wherein the magnetic yoke is a main pole of a perpendicular magnetic recording magnetic head. (6) Claims 1 to 5 are characterized in that a current path formed by an @ line or a thin film deposition method is provided for applying a bias magnetic field to the magnetoresistive element.
The magnetoresistive magnetic head according to any one of the above items. (7) A magnetoresistive magnetic head according to claim 6, wherein the current path formed by a winding or a thin film deposition method also serves as a recording current winding. C

Claims (6)

[Claims] (1) By providing a magnetoresistive element close to a part of the magnetic yoke and magnetically coupling the magnetic yoke and the magnetoresistive element, the electric resistance of the magnetoresistive element is changed to obtain a reproduction signal. A magnetoresistive magnetic head characterized by being configured as follows. (2) A magnetoresistive magnetic head according to claim 1, wherein the magnetic yoke is a magnetic core. (3) The magnetic yoke is the magnetic substrate of the thin film magnetic head,
2. A magnetoresistive magnetic head according to claim 1, wherein the magnetoresistive element is set in a position close to a current path. (4) A magnetoresistive magnetic head according to claim 3, wherein the magnetoresistive element is covered with a magnetic layer. (5) For the magnetic yoke, go to the perpendicular magnetic record 8! ! 2. A magnetoresistive magnetic head according to claim 1, wherein the magnetoresistive magnetic head is a main pole of a magnetic head. (6) Claims 1 to 5 are characterized in that a current path formed by a winding or a thin film deposition method is provided for applying a bias magnetic field to the magnetoresistive element.
The magnetoresistive magnetic head according to any one of the above items. The magnetoresistive magnetic head according to claim 6, wherein the current path formed by a force winding or a thin film deposition method also serves as a recording current winding.