JPH0256713A - Magneto-resistance effect type reproducing head - Google Patents

Abstract

PURPOSE:To prevent the generation of Barkhausen noise by forming a shunt bias conductor film from a permanent magnet film made from a hard magnetic metallic film magnetized in the core width direction of a magneto-resistance effect element. CONSTITUTION:On a signal detecting part 21a of an MR element 21 in place of a shunt bias conductor film such as a conventional Ti, a hard magnetic metallic film 22 composed of a Co-Ni, Co-P, etc., is directly joined, and on pullout terminals 21b and 21c of both edges of the detecting part 21a, a non- magnetic conductor film 23 composed of Ca is directly joined. The above- mentioned hard magnetic metallic film 22 is magnetized in the core width W direction of the MR element 21 and constituted as a permanent magnetic film 24. By such a constitution, since the permanent magnetic film 24 is directly joined on a signal detecting part 21a of the MR element 21, it is not necessary to enlarge the residual magnetization of the permanent magnetic film 24, the impression of the bias magnetic field to linearly operate the permanent magnet film and the impression of the magnetic field in the core width W direction of the MR element 21 by the permanent magnetic film 24 can be executed.

Description

[Detailed Description of the Invention] [Summary] Regarding the structure of a shunt bias type magnetoresistive reproducing head for reproducing information recorded on a magnetic tape or a magnetic disk, etc., the magnetic domain structure of an MR element with a narrow core width is disclosed. The purpose is to easily apply a sufficient magnetic field in the core width direction of the MR element by providing a magnetic field applying means necessary to control the magnetic recording medium so as not to adversely affect the magnetic recording medium. In an MR read head in which a magnetoresistive element to which a shunt bias conductor film is directly bonded is sandwiched between nonmagnetic insulating layers, a hard magnetic metal film is used as the shunt bias conductor film in the core width direction of the magnetoresistive element. The structure uses a permanent magnet film magnetized to .

[Industrial application field]

The present invention relates to the structure of a shunt bias type magnetoresistive reproducing head for reproducing information recorded on a magnetic tape or a magnetic disk.

Shunt bias type magnetoresistive playback head (
An MR head (hereinafter referred to as an MR head) is a magnetic head that uses a shunt bias conductor and a magnetoresistive element (hereinafter referred to as an MR element), and the electrical resistance value of the MR element changes depending on the strength of the medium magnetic field. Utilizing the characteristics, a constant current (
By supplying a sense current (sense current), the magnetic field generated by the current flowing through the shunt bias conductor film is applied as a bias magnetic field that operates the MR element at an appropriate bias point, and the magnetic field is applied in the direction of the hard axis perpendicular to the axis of easy magnetization. This system detects the change in resistance of the MR element due to the medium signal magnetic field as a voltage change, and is attracting attention as a read head that does not depend on the running speed of the recording medium and can provide a large output.

Since the resistance change of the MR element is caused by the rotation of the magnetization vector, in order to obtain a stable output, it is necessary to control the magnetic domain structure of the MR element so that the magnetization vector rotates smoothly. From this point of view, a single magnetic domain structure is most desirable as a domain structure.

By the way, a magnetoresistive film (M
R films) are generally given induced magnetic anisotropy by a film formation method in a magnetic field so that the axis of easy magnetization points in the core width direction, but as recording media become more densely recorded, the track becomes narrower. As the core width of the MR head becomes smaller, the demagnetizing field in the core width direction increases, so the magnetic domain structure of the MR film is disturbed and many magnetic domains are formed.

Therefore, during reproduction, reproduction waveform distortion called Barkhausen noise due to such irregular movement of the magnetic domain wall of the MR element appears in the reproduction output, which tends to significantly deteriorate the reproduction signal quality. Therefore, it is desired to improve the quality of the reproduced signal by suppressing the occurrence of such Barkhausen noise.

[Conventional technology]

As shown in Figure 3, the conventional shunt bias type MR head that suppresses the generation of Barkhausen noise has Mn
- SiO□ or
As shown in the partially enlarged perspective view of FIG. 4, a shunt bias conductor film 14 made of a non-magnetic metal such as Ti is interposed with a non-magnetic insulating layer 13 such as Ti. ! [An MR element 15 made of bonded permalloy (Ni-Fe) is arranged,
Further, on both sides of the MR element 15 in the direction of the core width W, the MR element 15
Hard magnetic films 16 and 17 made of Co--Ni or the like are magnetized in the direction of the core width W of the R element 15.

By applying a magnetic field in the direction of the core width W to the MR element I5 using these two magnetized hard magnetic films 16 and 17, the irregular movement of the domain wall is caused by narrowing the core width of the MR element 15. This eliminates the occurrence of Barkhausen noise.

[Problem to be solved by the invention]

However, in the MR head having such a configuration, the distance between the two hard magnetic films 16 and 17 disposed on both sides of the MR element 15 in the core width W direction is the distance between the MR element 15 and each hard magnetic film. 16. The distance from 17 was set to 2 due to the relationship between film formation technology
It is difficult to reduce the core width to 3 μm or less, and when the core width W is added, the core width inevitably becomes larger, resulting in a disadvantage that a sufficient magnetic field cannot be applied to the MR element 15.

Therefore, in order to apply a sufficient magnetic field to the MR element 15,
It is sufficient to increase the residual magnetization of each magnetized hard magnetic film 16.17, but in such a configuration, the magnetic recording medium 18 close to the hard magnetic film 16.17, which generates a strong magnetic field during reproduction,
A problem arises in that information already recorded in a portion is demagnetized.

In view of the above-mentioned conventional problems, the present invention provides magnetic field application means necessary for controlling the MR element's partition structure with a narrow core width in a manner that does not adversely affect the magnetic recording medium.
It is an object of the present invention to provide a novel magnetoresistive reproducing head that can easily apply a sufficient magnetic field in the core width direction of an R element.

[Means for Solving the Problems] In order to achieve the above-mentioned objects, the present invention includes a magnetoresistive element in which a shunt bias conductor film is directly bonded between two shielding magnetic bodies, sandwiched between nonmagnetic insulating layers. In the provided magnetoresistive playback head, the shunt bias conductor film is a permanent magnet film in which a hard magnetic metal film is magnetized in the width direction of the core of the magnetoresistive element.

[Function] In the magnetoresistive read head (MR head) of the present invention, a permanent magnet film in which a hard magnetic metal film is magnetized in the core width direction of the MR element is used as a shunt bias conductor film that is directly bonded to the MR element. Therefore, the magnetic field generated by the current flowing through the permanent magnet film is applied as a bias magnetic field to operate the MR element at an appropriate bias point, and the MR element is The magnetic field required to control the magnetic domain structure in the core width direction can also be easily applied.As a result, stable output characteristics without Barkhausen noise can be obtained.

〔Example〕

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

FIG. 1 is a schematic cross-sectional view of essential parts showing an embodiment of the magnetoresistive reproducing device according to the present invention, and parts equivalent to those in FIG. 3, which describes the conventional example, are given the same reference numerals. .

In this embodiment, as shown in the figure, SiO□ or Affi zoz is used between a magnetic substrate 11 that also serves as a shielding magnetic material made of Mn-Zn ferrite or the like and a shielding magnetic material 12 made of permalloy (Ni-Fe) or the like. Permalloy (Ni-P) is disposed with a non-magnetic insulating layer 13 interposed
e) etc., and as shown in the partially enlarged perspective view of FIG.
A hard magnetic metal film 22 made of Co-Ni or Co-P is directly bonded to the lead terminals 21b and 21c at both ends of the detection part 21a instead of the conventional shunt bias conductor film such as Ti. is a nonmagnetic conductive film 2 made of Cu
3 are directly joined. and the hard magnetic metal film 22
is magnetized in the direction of the core width W of the MR element 21 to form a permanent magnet film 2.
It is configured as 4.

With this configuration, the permanent magnet film 24 is directly bonded onto the signal detection section 21a of the MR element 21, so there is no need to increase the residual magnetization of the permanent magnet film 24, and this permanent magnet Applying a bias magnetic field to linearly operate the MR element 21 by a current flowing through the film 24;
Since the permanent magnet film 24 can apply magnetism in the direction of the core width W of the MR element 21, generation of Barkhausen noise is suppressed, and stable reproduction output characteristics without reproduction waveform distortion can be obtained.

〔Effect of the invention〕

As is clear from the above description, according to the magnetoresistive reproducing head according to the present invention, the magnetic domain structure of the MR element can be easily controlled, and stable reproduction output characteristics without generation of pulse noise can be obtained. It has excellent effects and is extremely advantageous in practice when applied as a reproducing head for magnetic recording media with narrow tracks.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view of a main part showing an embodiment of a magnetoresistive reproducing head according to the present invention, and FIG. FIG. 3 is a schematic cross-sectional view of a main part for explaining a conventional magnetoresistive read head, and FIG. 4 shows a magnetoresistive element in a conventional magnetoresistive read head. FIG. 3 is a partially enlarged perspective view for explaining the relationship with a hard magnetic film for applying a magnetic field. 1 and 2, 11 is a magnetic substrate, 12 is a shielding magnetic material, 13 is a non-magnetic insulating layer, 18 is a magnetic recording medium, 21 is an MR element, 21a
21b and 21c are lead terminals, 22 is a hard magnetic metal film, 23 is a nonmagnetic conductor film, and 24 is a permanent magnet film. 4i9HcMR-1"GJsu'neet, aaiim Figure 1 Main e island HR plan Tomasama 1ki Imabikito Kato Takashiba ma/lh
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Claims (1)

[Claims] A magnetoresistive element (21) in which a shunt bias conductor film is directly bonded between two shielding magnetic bodies (11, 12).
In the head configuration in which the shunt bias conductor film is sandwiched between non-magnetic insulating layers (13), the shunt bias conductor film is a hard magnetic metal film (22).
A magnetoresistive reproducing head comprising a permanent magnet film (24) magnetized in the core width direction of a magnetoresistive element (21).