JPH05189725A - Thin-film magnetic head - Google Patents

Abstract

PURPOSE:To prevent the generation of Barkhausen noises by forming a axis of easy magnetization of a magneto-resistance effect element, which is constitut ed of three layers consisting of a ferromagnetic thin film, nonmagnetic thin film and ferromagnetic thin film, by inclining the axis of easy magnetization at a prescribed angle with its longitudinal direction, then providing high-coercive force films at both ends of the element. CONSTITUTION:The magneto-resistance effect element 2 is constituted of two layers of the ferromagnetic thin films 2a, 2b and the nonmagnetic thin film 5 which is an intermediate layer. The axis of easy magnetization of this effect element 2 is inclined by 5 to 40 deg. with its longitudinal direction and the high- coercive force films 8 are provided at both ends of the effect element 2. As a result, the axis of easy magnetization of the effect element 2 is stabilized to a desired angle by the weak magnetic field of the high-coercive force films 8, by which the anisotropic dispersion angle of the axis of easy magnetization of the effect element 2 is made smaller even if the length in the longitudinal direction (stripe direction) increases. The discontinuous points of a magnetization curve are thereby moved to the outside of an operating range and the generation of the Barkhausen noises is averted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive thin film magnetic head which utilizes the magnetoresistive effect of a ferromagnetic material and detects a change in a signal magnetic field as a change in electrical resistance.

[0002]

2. Description of the Related Art A magnetoresistive thin film magnetic head reads the recorded contents of a magnetic recording medium by detecting a resistance change of a ferromagnetic thin film due to a signal magnetic field as a change in voltage across the magnetic thin film. Various proposals have heretofore been made in order to prevent Barthausen noise accompanying magnetization switching when a ferromagnetic thin film is magnetized by a signal magnetic field. Conventional magnetoresistive thin film magnetic head (hereinafter referred to as MR
The head. ) Will be described with reference to FIGS. 4 and 5.

In the MR head of FIG. 4, Barkhausen noise is removed by the interaction of a sense current for detecting a signal magnetic field, in which a metal ferromagnetic material having a magnetoresistive effect and a non-magnetic material are arranged in a plurality of layers. It was done. The magnetoresistive effect element 22 of this MR head is a ferromagnetic layer on a non-magnetic substrate 21 such as glass so as to induce an easy axis of magnetization in the longitudinal direction (track direction) by vapor deposition or sputtering in a magnetic field. A Ni-Fe thin film 22
a is formed, and a non-magnetic film 25 such as SiO or SiO ₂ is formed thereon with a film thickness of 10Å to 1000Å. further,
The Ni-Fe thin film 22b is laminated and then patterned by etching. Conductor thin films are formed as electrodes 23 on both ends of the magnetoresistive effect element 22. When an MR head is used, a sense current for detecting the resistance value (strength of the signal magnetic field) of the magnetoresistive effect element 22 is passed, but by making the magnetoresistive effect element 22 have the above structure, The magnetic fields generated by the sense currents of the Ni-Fe films 22a and 22b interact with each other, and both films are made into a single magnetic domain. As a result, Barkhausen noise due to magnetization switching can be suppressed.

On the other hand, in the MR head of FIG. 5, Barkhausen noise is prevented by making the magnetoresistive effect element into a single magnetic domain by a bias magnetic field and a high coercive force film. In this MR head, a conductor thin film 36 for applying a desired bias magnetic field in the stripe width direction of a magnetoresistive effect element is formed on a non-magnetic base material 31 via an interlayer insulating layer, and then a single-layer magnetoresistive effect is formed. The element 32 is laminated, and the high coercive force film 38 is formed on both ends thereof. This high coercive force film 38
The weak magnetic field causes the magnetoresistive effect element 32 to have a single magnetic domain. The axis of easy magnetization is set in a direction inclined by 5 ° to 40 ° with respect to the longitudinal direction of the magnetoresistive effect element 32. With this structure, the magnetoresistive effect element 32 is made into a single magnetic domain, and the easy axis of magnetization of the magnetoresistive effect element 32 is tilted at an anisotropic dispersion angle or more, thereby suppressing Barkhausen noise. It becomes possible.

Although the conventional example shown above is an MR head having a basic structure, a yoke type thin film magnetic head for guiding a signal magnetic field of a magnetic recording medium to a magnetoresistive effect element by a yoke composed of a metal ferromagnetic material is also used. With the magnetoresistive effect element having the above structure, the same effect as the above is obtained.

[0006]

However, the above two examples of M
The R head has the following drawbacks.

In the case of the MR head shown in FIG. 4, generally, the direction of the easy axis of magnetization of the magnetoresistive effect element 22 often causes angular dispersion in the steps after the film formation, and the magnetoresistive effect element 22 is manufactured even after the MR head is manufactured. Not all areas face the same direction. It is difficult to eliminate the distribution of the easy axis of magnetization by the interaction between the magnetoresistive films 22a and 22b. Therefore, the Barkhausen noise caused by the magnetization switching is set for the signal magnetic field, and there is a drawback that the yield of the magnetoresistive effect element is significantly reduced.

On the other hand, in the case of the magnetic head shown in FIG. 5, it is possible to move the discontinuity point of the magnetization curve due to the magnetization switching of the magnetoresistive effect element 32 to the outside of the operation range, and to avoid the occurrence of Barkhausen noise. it can. However, in a reproducing head for reproducing a signal having a wide track width such as an analog signal of a DCC (Digital Compact Cassette), it is necessary to increase the length of the magnetoresistive effect element 32 in the track (stripe) direction. When the film thickness of the magnetoresistive effect element 32 becomes large, the weak magnetic field applied by the high coercive force films 38 provided at both ends of the magnetoresistive effect element 32 becomes weak at the central part of the magnetoresistive effect element 32. The anisotropic dispersion angle of becomes large. Due to the dispersion of the easy axis of magnetization, magnetization switching occurs within the operating range of the magnetoresistive effect element 32, and Barkhausen noise occurs, which is a disadvantage.

In order to solve the above problems, the present invention provides a thin film magnetic head capable of preventing generation of Barkhausen noise even when the length of the magnetoresistive effect element in the stripe direction becomes long. To aim.

[0010]

According to the present invention, a magnetoresistive effect element for detecting a change in a signal magnetic field of a magnetic recording medium as a change in resistance value is composed of a ferromagnetic thin film, a non-magnetic thin film and a ferromagnetic thin film. In addition to the above structure, the easy axis of magnetization of the magnetoresistive effect element is formed to be inclined at 5 ° to 40 ° with respect to the longitudinal direction thereof, and further high coercive force films are provided at both ends of the magnetoresistive effect element. To do.

Furthermore, the present invention is characterized in that, in the above-mentioned invention, the composition of the non-magnetic thin film is a substance having a conductivity equal to or less than that of the ferromagnetic thin film.

[0012]

According to the present invention, the magnetoresistive effect element is composed of two layers of ferromagnetic thin film and the intermediate nonmagnetic thin film, and the easy axis of magnetization of this magnetoresistive effect element is 5 ° to 40 ° with respect to the longitudinal direction.
Furthermore, a high coercive force film was provided at both ends of this magnetoresistive effect element. As a result, the easy axis of magnetization of the magnetoresistive effect element is stabilized at a desired angle by the weak magnetic field of the high coercive force film, and the easy axis of magnetization of the magnetoresistive effect element varies even if the length in the longitudinal direction (stripe direction) becomes long. It is possible to reduce the dispersion angle of the directionality and move the discontinuity point of the magnetization curve to the outside of the operating range to avoid the occurrence of Barkhausen noise.

If the conductivity of the non-magnetic thin film in the magnetoresistive effect element is lower than that of the ferromagnetic thin film forming the magnetoresistive effect element, the signal detection current does not flow in the stripe direction but is insulated in the film thickness direction. The signal detection current flows through each of the ferromagnetic thin films forming the magnetoresistive element, and the detection efficiency can be improved.

[0014]

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

FIG. 1 is an external perspective view of a thin film magnetic head according to an embodiment of the present invention. This thin-film magnetic head comprises a magnetoresistive effect element 2 in which a metal ferromagnetic layer 2a, a nonmagnetic layer 5 and a metal ferromagnetic layer 2b are laminated. Further, a high coercive force film 8 is formed on both ends of the magnetoresistive effect element 2. The lead conductor 3 is connected to the magnetoresistive effect element 2 through the high coercive force film 8. The manufacturing of such a thin film magnetic head is performed in the following steps.

On a non-magnetic substrate 1 such as glass, Ni-Fe
Such as a metal ferromagnetic layer 2a having a magnetoresistive effect, SiO,
A non-magnetic layer 5 such as SiO ₂ and a metal ferromagnetic layer 2b similar to 2a are sequentially laminated and then patterned to form a magnetoresistive effect element 2. At this time, the metallic ferromagnetic thin film having a magnetoresistive effect such as Ni-Fe induces the easy axis of magnetization at a desired angle by a magnetic field vapor deposition method or the like. Further, as the non-magnetic layer 5, a refractory metal such as Nb or Ti whose conductivity is equal to or less than that of the metal ferromagnetic material of the magnetoresistive thin film is used, and the magnetoresistive effect element 2 is formed by an ion-rimming method or the like. Patterning is also possible. Next, a high coercive force film 8 of Co-P or the like is formed on both ends in the longitudinal direction of the magnetoresistive effect element 2 by a plating method or the like, and a lead conductor portion 3 for flowing a signal detection current through the magnetoresistive effect element.
Are formed on the insulating layer 7. The easy axis of magnetization of the magnetoresistive element 2 is 10 ° clockwise with respect to the stripe direction.
Is tilted.

With such a structure, even if the length of the magnetoresistive effect element 2 in the stripe direction becomes long, the anisotropic dispersion angle of the easy axis of magnetization of the magnetoresistive effect element 2 can be made small. In addition, the discontinuity point of the magnetization curve can be moved outside the operating range of the magnetoresistive effect element 2. This makes it possible to avoid the occurrence of Barkhausen noise during medium reading.

2 and 3 are views showing a yoke type MR head (YMR head) which is another embodiment according to the present invention. 2 is a perspective view of the same YMR head, and FIG. 3 is the same YM head.
It is sectional drawing of R head. In this figure, parts having the same functions as those of the MR head shown in FIG. This YMR head is provided with an upper yoke 9 (9a, 9b) for guiding a signal magnetic field of magnetic recording to the magnetoresistive effect element 2 on a ferromagnetic substrate 11 such as Mn-Zn ferrite which functions as a lower yoke. There is. The upper yoke 9 is made of a metal ferromagnetic material. A bias conductor 6 is provided between the magnetoresistive effect element 2 and the lower yoke (ferromagnetic substrate) 11. A bias current for applying a bias magnetic field to the magnetoresistive effect element 2 is passed through the bias conductor. In this YMR head as well, similar to the MR head of FIG. 1, the easy axis of magnetization of the magnetoresistive effect element 2 is inclined at a predetermined angle with respect to its longitudinal direction.

[0019]

As described above, according to the present invention, even if the length of the magnetoresistive effect element in the stripe direction becomes long, the anisotropy dispersion angle of the easy axis of magnetization can be made small, and the bulk It is possible to eliminate the occurrence of Hausen noise. As a result, it is possible to improve the production yield and improve the quality of the reproduction output signal.

[Brief description of drawings]

FIG. 1 is an external perspective view of an MR head according to an embodiment of the present invention.

FIG. 2 is an external perspective view of a yoke type MR head according to another embodiment of the present invention.

FIG. 3 is a sectional view of the same yoke type MR head.

FIG. 4 is a diagram showing a conventional thin film magnetic head.

FIG. 5 is a diagram showing a conventional thin film magnetic head.

[Explanation of symbols]

 1-non-magnetic substrate 2-magnetoresistive element 2a, 2b-metal ferromagnetic thin film 3-lead conductor 5-non-magnetic film 6-bias conductor 9 (9a, 9b) -upper yoke 11-ferromagnetic substrate (lower side yoke)

Claims (2)

[Claims] 1. A magnetoresistive effect element for detecting a change in a signal magnetic field of a magnetic recording medium as a change in resistance value is constituted by three layers of a ferromagnetic thin film, a nonmagnetic thin film and a ferromagnetic thin film, and the magnetoresistive effect is obtained. A thin film magnetic head characterized in that an easy axis of magnetization of the element is formed to be inclined at an angle of 5 ° to 40 ° with respect to its longitudinal direction, and further high coercive force films are provided at both ends of the magnetoresistive effect element. 2. The thin-film magnetic head according to claim 1, wherein the composition of the non-magnetic thin film is a substance having a conductivity equal to or lower than that of the ferromagnetic thin film.