JP3040892B2 - Magnetoresistive thin film magnetic head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magneto-resistance effect type thin film magnetic head for reading out information written on a magnetic recording medium by utilizing a magneto-resistance effect, and more particularly to a structure for obtaining a stable reproduction output. It was done.

[0002]

2. Description of the Related Art A magnetoresistive thin-film magnetic head is mounted on a magnetic recording / reproducing apparatus for recording / reproducing information on / from a magnetic recording medium and used as a read head.

A conventional thin film magnetic head of the magnetoresistive effect type comprises:
Basically, as shown in FIG. 3A, a magnetic substrate 4 made of ferrite or the like, a magnetoresistive element 1 made of a Ni—Fe alloy thin film or the like, and a drive current supplied to the magnetoresistive element 1 It comprises a pair of electrodes 3a, 3b, and a front yoke 7 and a back yoke 8 for guiding a signal magnetic flux output from the magnetic tape from a surface 6 sliding on the magnetic tape to the magnetoresistive element 1. The magnetoresistive element 1 and the front yoke 7 are stacked on a magnetic substrate 4 via an insulating layer as shown in the cross-sectional view of FIG. 3B, and one end of the back yoke 8 is connected to the magnetic substrate 4. They are stacked in contact with each other.

[0004] The insulating layer 5 interposed between the magnetic base 4 and the front yoke 7 determines the gap interval of the magnetic head. The magnetic tape has a sliding surface 6 and a front yoke 7.
The signal magnetic flux output from the magnetic tape is slid in contact with the end surface of the paper and travels in the vertical direction of the paper surface, and is taken into a closed magnetic path including the front yoke 7, the magnetoresistive element 1, the back yoke 8, and the magnetic base 4. The magnetoresistive element 1 changes the resistance according to the strength of the magnetic flux flowing through the closed magnetic circuit. As a result, the voltage between the electrodes 3a and 3b changes according to the strength of the magnetic flux.
That is, it changes according to the signal recorded on the magnetic tape.

In this magnetoresistive thin film magnetic head,
The challenge is to maintain good sensitivity, to provide a stable output without being disturbed by disturbance magnetic fields, and to reduce Barkhausen noise. It is necessary to make the magnetoresistive effect element into a single magnetic domain so that the direction of magnetization of the effect element is entirely uniform.

Therefore, conventionally, a magnetic field is externally applied to the magnetoresistive element of the magnetoresistive thin film magnetic head,
The magnetic domains are adjusted so that the magnetization of the magnetoresistive element is aligned in the longitudinal direction.

FIG. 4 shows, in an enlarged manner, only a portion related to the magnetoresistive element of the magnetoresistive thin film magnetic head in which such measures are taken. In this magnetoresistive element 1, hard magnetic films 2a, 2b, 2c, 2d and 2e made of a Co-Pt alloy film or the like are laminated on some parts thereof, and electrodes 3a and 3b is laminated.

The hard magnetic films 2a to 2e are magnetized so as to apply a magnetic field to the magnetoresistive element 1 in the direction of the axis of easy magnetization. Is controlled.

[0009]

However, in the conventional magnetoresistive thin film magnetic head, since the hard magnetic films 2a to 2e are formed directly on the magnetoresistive element 1, the hard magnetic films 2a to 2e are formed. Operate as a composite film with the magnetoresistive element 1. The hard magnetic film is formed using a material having a large coercive force. On the contrary, since the magnetoresistive element 1 is made of a material having a small coercive force, the exchange interaction of the ferromagnetic exchange coupling at the boundary between the two layers is performed. Accordingly, the magnetization directions of the two-layer film become the same, and the coercive force of the composite film takes an intermediate value between the two films.

As a result, the coercive force of the thin film magnet decreases, and the characteristics of the thin film magnet deteriorate. If the characteristics of the thin film magnet deteriorate, the stability of the magnetoresistive effect element 1 against a disturbance magnetic field is impaired, and a stable reproduction output of the magnetoresistive effect type thin film magnetic head cannot be obtained. Further, the adjustment of the magnetic domain of the magnetoresistive element 1 becomes inappropriate due to the deterioration of the characteristics of the thin film magnet, and a reverse magnetization is formed in the magnetoresistive element, so that Barkhausen caused by the irregular change of the domain wall. Noise will be generated.

An object of the present invention is to solve such a conventional problem and to provide a magnetoresistive thin film magnetic head capable of reducing noise and obtaining a stable reproduction output.

[0012]

SUMMARY OF THE INVENTION Therefore, the present invention provides a magnetoresistive element including a magnetoresistive element, an electrode for applying a current to the magnetoresistive element, and a hard magnetic film for applying a magnetic field to the magnetoresistive element. in effect type thin film magnetic head, electrostatic
The magnetoresistive element between the poles is divided into a plurality of parts, and the hard magnetic film is formed in each of the gaps between the divided magnetoresistive elements.

In addition, a hard magnetic film is formed in the gap so as not to contact the magnetoresistive element, and a conductor film covering the hard magnetic film is formed. The effect elements are electrically connected.

[0014]

As a result, the hard magnetic film has a substantially single-layer structure and does not cause a decrease in coercive force. Therefore, a large magnetic field can be applied to the magnetoresistive effect element,
A single magnetic domain of the magnetoresistive element is realized, the reproduction output of the magnetoresistive thin film magnetic head is stabilized, and noise is reduced.

[0015]

【Example】

(First Embodiment) In the magnetoresistive thin film magnetic head according to the first embodiment, as shown in FIG. 1, a magnetoresistive element made of a Ni—Fe alloy thin film or the like is divided into a plurality of 1a, 1b, 1c and 1d. A Co-P alloy thin film or a Co-P alloy thin film is formed at a gap between each of the magnetoresistive elements 1a to 1d and at a connection point between the magnetoresistive elements 1a and 1d and the electrodes 3a and 3b made of Au / Cr or Cu / Cr alloy thin film. Hard magnetic film 2 made of Co-Pt alloy thin film etc.
a, 2b, 2c, 2d, and 2e are formed. Hard magnetic film 2a-2e
Are arranged so as to slightly overlap with the ends of the magnetoresistive elements 1a to 1d.

Since the overlap between the hard magnetic films 2a to 2e and the magnetoresistive elements 1a to 1d is small as described above, the hard magnetic film is substantially a single-layer film compared to the conventional one in which a complete composite film is formed. Can be seen. Therefore, the coercive force of the hard magnetic film can be maintained as a single-layer film without lowering, and the hard magnetic film is applied to the magnetoresistive elements 1a to 1d in the direction of the axis of easy magnetization as a high-quality thin film magnet. Magnetic field can be applied.

Therefore, in the magnetoresistive elements 1a to 1d, since a large magnetic field is applied from the thin film magnets 2a to 2e,
A single magnetic domain is realized in a stable state, and in a magnetoresistive thin-film magnetic head, reproduction output is stabilized, stability against a disturbance magnetic field is improved, and noise is further reduced.

(Second Embodiment) In the magneto-resistance effect type thin film magnetic head according to the second embodiment, as shown in FIG.
1a, 1b, and 1a, 1b,
1c and 1d, and a Co-P is formed in a gap portion of the magnetoresistive effect elements 1a to 1d and a portion adjacent to the magnetoresistive effect elements 1a and 1d so as not to contact the magnetoresistive effect elements 1a to 1d.
Form hard magnetic films 2a, 2b, 2c, 2d, 2e made of a t-alloy thin film and the like, and further cover the gaps of the magnetoresistive element so as to electrically conduct between the divided magnetoresistive elements. The conductor films 3c, 3d, 3e are formed. Further, one ends of the electrodes 3a and 3b for applying a drive current are extended so as to be connected to the magnetoresistive elements 1a and 1d, respectively.

The conductor films 3c, 3d, and 3e have the same A as the electrodes 3a and 3b.
The electrodes 3a and 3b are formed simultaneously with a material such as u / Cr or Cu / Cr alloy, and the area thereof is set to a sufficient and minimum area to cover the gap. The hard magnetic films 2a to 2e are formed in a non-contact state while being sufficiently close to the magnetoresistive elements 1a to 1d.

Since the hard magnetic films 2a to 2e of the magnetoresistive thin film magnetic head are not in contact with the magnetoresistive elements 1a to 1d at all, the characteristics as a single-layer film are maintained.
Acts on a magnetoresistive element as a good quality thin film magnet. Therefore, the magnetoresistive effect elements 1a to 1d include the thin film magnets 2a to
Since a large magnetic field is applied from 2e, a single magnetic domain is realized in a stable state, and in the magnetoresistive thin-film magnetic head, the reproduction output is stable, the stability against disturbance magnetic fields is improved, and noise is further reduced. Reduce. In addition, since the magnetic field from each hard magnetic film having a large coercive force acts strongly on each edge of the divided magnetoresistive element, disturbance is caused by a magnetic wall at each edge of the divided magnetoresistive element. There is no possibility that a state in which stability to a magnetic field is impaired occurs.

The arrangement of the hard magnetic film is determined in consideration of the reproduction sensitivity of the magnetoresistive element and the stability to a disturbance magnetic field. That is, when the number of hard magnetic films is increased, a large magnetic field is applied to the magnetoresistive element, so that the stability against a disturbance magnetic field is improved. On the other hand, when the number of hard magnetic films is increased, the magnetization of the magnetoresistive element becomes difficult to rotate in accordance with the signal magnetic field, resulting in a decrease in sensitivity. Therefore, in an actual magnetoresistive thin-film magnetic head, it is necessary to determine the number of hard magnetic films in consideration of these points.

[0022]

As is clear from the above description of the embodiment, the magnetoresistive thin-film magnetic head of the present invention can stabilize the single magnetic domain state of the magnetoresistive element, thereby making it possible to reduce the disturbance magnetic field. Stability is improved, and a good reproduction output with little noise can be obtained.

[Brief description of the drawings]

FIG. 1 is a plan view of a magnetoresistive element portion of a magnetoresistive thin film magnetic head according to a first embodiment of the present invention;

FIG. 2 is a plan view of a magnetoresistive element of a magnetoresistive thin film magnetic head according to a second embodiment of the present invention;

3A and 3B are an external view and a sectional view of a conventional magnetoresistive thin film magnetic head,

FIG. 4 is a plan view of a magnetoresistive element portion of a conventional magnetoresistive thin film magnetic head.

[Explanation of symbols]

 1a, 1b, 1c, 1d Magnetoresistive element 2a, 2b, 2c, 2d, 2e Hard magnetic film 3a, 3b Electrode 4 Magnetic substrate 5 Gap insulating layer 6 Magnetic tape sliding surface 7 Front yoke 8 Back yoke

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yuji Nagata 1006 Oaza Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. (56) References JP-A-61-255525 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) G11B 5/39

Claims (2)

(57) [Claims] And 1. A magnetoresistive element, and electrodes for applying an electric current to the magnetoresistive effect element, in the magnetoresistance effect type thin film magnetic head and a hard magnetic film for applying a magnetic field to said magneto-resistive element, said A magnetoresistive thin-film magnetic head , wherein the magnetoresistive element between electrodes is divided into a plurality of parts, and the hard magnetic film is formed in each of the gaps between the divided magnetoresistive elements. 2. The method according to claim 1, wherein the hard magnetic film is formed in the gap so as not to contact the magnetoresistive element.
2. The magnetoresistive effect type according to claim 1, wherein a conductive film covering the hard magnetic film is formed, and the magnetoresistive elements on both sides of the gap are electrically connected by the conductive film. Thin film magnetic head.