JPH09167317A - Magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a MR head with little variation in output by providing a magnetresistive element between 2-layered magnetic shields and making the recess width of the tip part of the magnetic shield smaller than the height of the recess. SOLUTION: Height (b) of a recessed part of a magnetic shield A is made larger than the with (a) of the recessed part. In this way, the stress in the direction of the width at the tip part of the magnetic shield A is relieved, and a tensile stress is added in the direction of the height, and a main magnetic domain and a closure magnetic domain are finely formed in the whole magnetic shield. Such a magnetic domain structure becomes a magnetization process of a rotary magnetization main body, and it can easily return to its original magnetic domain structure when an impressed current is switched off.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive head used in a magnetic disk device.

[0002]

2. Description of the Related Art For a small disk, an MR head using a magnetoresistive effect (MR) element provided between two layers of magnetic shields as a reproducing head, and an electromagnetic head whose output does not depend on the peripheral speed of the disk as a recording head. MR using inductive magnetic head
/ Inductive composite magnetic heads (recording / playback separation type magnetic heads) are widely used.

In this composite magnetic head, a magnetic flux generated by passing a current through a coil is guided to the magnetic core in the recording head, and the magnetic flux leaks to the outside in a gap of the magnetic core to record a signal on a recording medium. . The magnetoresistive effect element for reproduction is a head that utilizes the phenomenon that its electric resistance changes due to an external magnetic field.

Next, FIG. 6 shows the structure of a general MR / inductive composite type magnetic head. Figure 6 (A) and (B) shows MR /
It is explanatory drawing of the prior art example of an inductive compound type magnetic head.

FIG. 6A is a sectional view and FIG. 6B is a plan view. In the figure, 1 is a magnetoresistive (MR) element, 2 is a lower magnetic shield, 3 is an upper magnetic shield (lower magnetic pole), 4 is an upper magnetic pole for writing, 5 is a write coil, 101 and 102 are magnetoresistive effect elements. The terminals (electrodes), 501 and 502 are the terminals of the light coil.

[0006]

Generally, in order to improve the linear recording density of the recording medium (disk), the MR head is
Magnetic shields are provided on both sides of the MR element. In the MR / inductive combined magnetic head, so-called yaw angle loss occurs due to the difference in distance between the MR element part of the reproducing head and the gap part of the recording head. Therefore, as shown in the schematic cross-sectional view of FIG. 2, a head having a structure in which one side of the magnetic shield and the magnetic pole of the recording head are combined has been considered.

As described above, since the MR head is a read-only head, it is necessary to combine it with a recording inductive head to form an MR / inductive composite type magnetic head when used in a magnetic disk device. Before the MR head was adopted, there was no difference in position between the recording track and the reproducing track because recording and reproducing were performed with a single inductive head. However, in the composite type head, there is a difference in distance between the MR element part for reproduction and the recording gap part for recording. Due to this difference in distance, a positional deviation occurs between the recorded track and the reproduced track, and output fluctuations occur due to a loss called yaw angle loss.

Magnetostriction usually occurs in a magnetic material, and the positive / negative of the magnetostriction (magnetostriction constant ± λ) can be controlled to some extent when a magnetic film is formed. In FIG. 2, the magnetic shield A
Is the tensile stress (σ
> 0) and negative magnetostriction (λ <0). At this time, the axis of easy magnetization is the slider surface (magnetic sensing surface).
Becomes parallel to and causes anisotropy.

Because the angle formed by the spontaneous magnetization and the tension σ is θ
Then, the energy E of elastic magnetic anisotropy can be expressed by the following equation.
(See Chikaku: “Physics of ferromagnets” p140), E = − (3/2) λσ cos 2θ where E = 0, which is the most stable state, is θ = π
/ 2, that is, the angle between spontaneous magnetization and σ is 90 °.

If the tip of the shield is wide, stress tends to occur in the width direction (direction parallel to the slider surface) due to its shape effect. Compared to when the width of the tip is wide, the force is dispersed and it is difficult to give anisotropy in the intended direction. As a result, the anisotropy becomes weaker toward the tip.

When the anisotropy is strong, the main magnetic domain (Figs. 1, 3,
4, 5 slender hexagonal magnetic domains occupy a large area, and reflux domains (magnetic domains that return magnetic flux so that magnetic flux does not hit the surface and create magnetic poles so as to keep magnetostatic energy low in the shield, The triangular magnetic domains adjacent to the outer circumference of the magnetic shield in FIGS. 1, 3, 4, and 5 are small. At this time, anisotropy is strongly generated in the longitudinal direction of the main magnetic domain, and the easy axis of magnetization is in the longitudinal direction of the main magnetic domain.

When the anisotropy becomes weak, the difference between the easy axis and the hard axis disappears, and the ratio of the area occupied by the reflux magnetic domain increases. When the area of the reflux magnetic domain becomes large, the magnetization process becomes a domain wall motion-dominant type, resulting in poor reproducibility of the magnetic domain structure and unstable output.

That is, in the conventional magnetic shield shape, as shown in FIG. 5 (A), since the width of the shield tip portion is wide, only the tip portion tends to have a tensile stress direction parallel to the slider surface. The magnetic anisotropy weakens toward the part.

When the magnetic anisotropy at the tip portion becomes weak, the ratio of the area occupied by the reflux magnetic domain to the total area of the magnetic shield A increases, and the magnetic domain structure shown in FIG. 5B or 5C can be easily obtained. Therefore, in Fig. 5 (C), a vertical cracked domain wall is formed perpendicular to the slider surface. In such a magnetic domain structure, when a current flows through the write coil during recording, the magnetic domain wall moving becomes the main magnetization process, and even if the current is removed, the original magnetic domain structure may not be restored, and a magnetic charge is generated near the slider surface. The direction and size of the magnetic charge differ with each recording. Such a magnetic charge changes the magnetic bias of the MR element (the bias magnetic field applied to set the waveform of the reproduction voltage to the linear operation point to increase the reproduction output) during reproduction, resulting in a large output to the MR head. It will cause fluctuations.

An object of the present invention is to obtain an MR head with less output fluctuation.

[0016]

To solve the above problems, 1) a magnetoresistive element is provided between two layers of magnetic shields, and the width of the recess at the tip of the magnetic shield is greater than the height of the recess. A small magnetic head, 2) a magnetic head having a magnetoresistive effect element provided between two layers of magnetic shields, the width of the tip of the magnetic shield being smaller than the height of the magnetic shield, or 3) the magnetic shield This is achieved by the magnetic head as described in 2 above, in which the width gradually increases from the tip to the inside.

According to the present invention, as shown in FIG. 1, by making the height b of the recess portion of the magnetic shield A larger than the width a of the recess portion, the stress in the width direction at the tip portion of the magnetic shield A is released. , A tensile stress is applied in the height direction, and a clean main domain and freewheeling domain are formed in the entire magnetic shield. Such a magnetic domain structure becomes a magnetization process mainly of magnetization rotation, and when the applied current is removed, the original magnetic domain structure is easily returned.

That is, due to the shape effect of the recess width or the width of the shield tip portion being wide, stress is easily generated in the width direction. Therefore, by reducing the width, only the tensile stress in the gap direction caused by the composition acts, and the eccentricity is enhanced in the entire shield, so that clear main and return magnetic domains can be formed.

Therefore, harmful magnetic charges are less likely to occur during reproduction, and the output fluctuation of the MR head can be suppressed.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a magnetic head of the present invention will be described with reference to the drawings. 3A and 3B are explanatory views of the first embodiment.

FIG. 3A is a block diagram of the head, and FIG. 3B is a magnetic domain structure model of the magnetic shield A. Figure 2, Figure 3 (A)
1 is a magnetoresistive (MR) element, 2 is a magnetic shield B, 3 is a magnetic shield A (also serves as a lower magnetic pole), 4 is an upper magnetic pole for writing, and 5 is a write coil for writing.

In this example, the magnetic shield A made of NiFe is used.
Has the illustrated recess structure, and the recess height b is the recess width a.
Since it is larger, the stress in the recess width direction can be relieved and the output fluctuation of the MR head can be relieved.

In FIG. 3B, a slender hexagonal magnetic domain occupying a large area is a main magnetic domain, and a triangular magnetic domain adjacent to the outer periphery of the magnetic shield is a return magnetic domain, and its occupied area ratio is small. At this time, anisotropy is strongly generated in the longitudinal direction of the main magnetic domain, and the easy axis of magnetization is in the longitudinal direction of the main magnetic domain.

FIGS. 4A and 4B are explanatory views of the second embodiment. FIG. 4A is a block diagram of the head, and FIG. 4B is a magnetic domain structure model of the magnetic shield A.

In the figure, 1 is a magnetoresistive (MR) element, 2 is a magnetic shield B, 3 is a magnetic shield A (also serves as a lower magnetic pole), 4 is an upper magnetic pole for writing, and 5 is a write coil for writing.

In this example, the magnetic shield A has a shape without a recess, but the height b of the magnetic shield A is larger than the tip end width a thereof. Even in this case, a magnetic domain structure having a small return magnetic domain area up to the tip of the magnetic shield A can be obtained, and the reproduction output can be stabilized.

[0027]

According to the present invention, it is possible to obtain an MR head with little output fluctuation during reproduction.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a sectional view of the head of the present invention.

FIG. 3 is an explanatory diagram of the first embodiment of the present invention.

FIG. 4 is an explanatory diagram of a second embodiment of the present invention.

FIG. 5 is an explanatory view of a conventional example.

FIG. 6 is a structural explanatory view of a conventional example.

[Explanation of symbols]

 1 Magnetoresistive (MR) element 2 Magnetic shield B 3 Magnetic shield A (lower magnetic pole) 4 Upper magnetic pole 5 Write coil

Claims (3)

[Claims] 1. A magnetic head having a magnetoresistive effect element provided between two layers of magnetic shields, wherein the width of the recess at the tip of the magnetic shield is smaller than the height of the recess. 2. A magnetic head having a magnetoresistive effect element provided between two layers of magnetic shields, wherein the width of the tip of the magnetic shield is smaller than the height of the magnetic shield. 3. The magnetic head according to claim 2, wherein the width of the magnetic shield gradually increases inward from the tip.