JPS58100217A - Magnetoresistance effect head - Google Patents

Abstract

PURPOSE:To facilitate control over the intensity and position of a permanent magnet and to obtain excellent characteristics, by arranging the permanent magnet for biasing behind the end part where cut grooves are formed in the track widthwise direction on the opposite end part of a magnetoresistance effect element to a magnetic recording medium. CONSTITUTION:A magnetoresistance effect (MR) head consists of a substrate 21, MR element 22 with 0.05mum film thickness, permanent magnet 24 for biasing having 0.2mum film thickness, and electrodes 2 and 3. The MR element 22 is formed in a parallelogram shape while having plural grooves 23 at an angle theta (20-60 deg.) to a trackwidthwise direction at the opposite end part to a magnetic recording medium 6. Because of the grooves 23 and permanent magnet 24, the magnetism M of the MR element 22 slants to a current (i) to optimize an operation point easily, thereby obtaining excellent characteristics over a wide bias magnetic field range.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetoresistive head, which has particularly good characteristics over a wide range of bias magnetic fields, and is suitable for easily controlling the strength and position of bias permanent magnets. The present invention relates to a magnetoresistive head having a structure.

As a magnetic head (hereinafter abbreviated as MR head) using a magnetoresistive element, one having the structure shown in FIG. 1 is generally known. That is, as shown in FIG. 1, one end surface of a magnetoresistive element (hereinafter abbreviated as MR element) 1 made of, for example, a nickel-iron alloy thin film is placed near or in contact with the magnetic recording medium. By this, the magnetization of the MR element 1 is changed by the magnetic field of the magnetic recording medium 6, and the change in the electrical resistance value of the MR element 1 due to the magnetoresistive effect is caused by the electrodes 2. This is taken out as a voltage change of the current source 4 connected through the filter.

Incidentally, reference numeral 5 denotes a permanent magnet disposed close to and facing the MR element 1, so that the permanent magnet 5 applies a bias magnetic field to the MR element 1. This permanent magnet 5 is connected to a magnetic recording medium 6
The sensitivity of the MR element 1 to signals from the MR element 1 is increased, and the response is brought closer to a linear response. That is, since the change in resistance value of the MR element 1 under a magnetic field is quadratic, a bias magnetic field is applied in the height direction of the MR element 1 using the permanent magnet 5, and the direction of magnetization is changed to M'R. It is made to form an angle of 45 degrees with the direction of the current flowing through the element 1, so that the operation of the MR element 1 is optimized.

However, the MR head having the structure shown in FIG. 1 has a problem in that the range of the optimum bias magnetic field strength is narrow and it is difficult to control the position of the permanent magnet.

1. When using multiple channels, there is a drawback that it is not easy to apply a bias magnetic field so that the magnetic field strength is the same for all MR elements.

The present invention has been made in view of the above, and an object of the present invention is to provide a magnetoresistive head that has good characteristics over a wide range of bias magnetic fields and that allows easy control of the strength and position of the bias permanent magnet. Our goal is to provide the following.

A feature of the present invention is that a cut groove is provided at the end of the magnetoresistive element on the side opposite to the magnetic recording medium, and the cut groove is provided at the end of the magnetoresistive element that is inclined with respect to the track width direction. The main feature is that a bias permanent magnet is placed at the rear of the side.

The present invention will be described in detail below with reference to the embodiments shown in FIGS. 2, 5, and 7, and FIGS. 6, 4, and 6.

FIG. 2 is a structural diagram showing an embodiment of the MR head of the present invention, in which (a) is a front view and (b) is a side view of (a). In FIG. 2, 21 is a substrate, 22 is an MR element made of a thin film of 0.05 μm thick having a magnetoresistive effect, such as a nickel-iron alloy, and the MR element 22 is, as shown in FIG. 2(a), It has a parallelogram shape with a plurality of grooves 23 formed at an angle θ (30 degrees in the embodiment) with the track width direction at the end opposite to the magnetic recording medium 6 side. 24 is a bias permanent magnet made of a thin film of magnetite or the like magnetized with a thickness of 0.2 μm as shown in the figure, and the MR element 22 and the permanent magnet 24 are formed on the surface of the substrate 21 as shown in the figure. . Reference numerals 2 and 3 are electrodes for passing current through the MR element 22. In the example shown in the figure, the track width W=150 μm in FIG. 2(a).

a = 157'm + groove width 1) of each cut groove 23 = 1
/1 m, distance from the bottom surface to the cut groove 23 m = 1
5 μm, and the height h of the MR element 22 is −50 μm. Note that in order to apply a uniform bias magnetic field to the MR element 22, it is desirable that the width of the permanent magnet 24 in the track width direction is larger than the track width W.

The notch H25 and the permanent magnet 24 allow the MR element 2
The magnetization M of 2 can be tilted with respect to the direction of the current i,
The operating point can be easily optimized. Note that since the M'R head according to the present invention utilizes the shape anisotropy effect of the magnetic material, it is desirable that a < h/5in0. Furthermore, since the angle of magnetization is mainly determined by the angle θ of the cut groove 23, the position of the permanent magnet 24 and fluctuations in magnetic field strength have little effect on the characteristics of the MR element 22.

The above will be explained using FIG. 6. FIG. 6 is a diagram showing the relationship between the bias magnetic field strength and the output level and second-order distortion level of the MR head, 61 is the characteristic curve of the output level of the MR head according to the present invention, and 32 is the second-order distortion level. This is the characteristic curve of 36 is a characteristic curve of the output level of the conventional bias type MR head shown in FIG. 1, shown for comparison. According to the embodiment of the present invention described above, when the bias magnetic field is 1000 or more, the second-order distortion is significantly improved, and when the magnetic field is higher than that, the distortion is maintained in that state. on the other hand,
The output level shows a gentle change even when the bias magnetic field is increased, and the range of the optimum bias magnetic field becomes very wide.

On the other hand, the output level of a conventional bias type MR head varies greatly depending on the bias magnetic field strength, and the optimum bias range is very narrow. As described above, the embodiment of the present invention exhibits good characteristics over a very wide range of bias magnetic fields, and the strength and position of the bias permanent magnet 24 can be easily controlled.

FIG. 4 shows f for the signal magnetic field of the MR head according to the present invention.
FIG. 3 is a characteristic diagram showing resistance changes of a VIR element.

FIG. 5 is a structural diagram showing another embodiment of the present invention (a and l are a front view, and (b) is a side view; the same parts as in FIG. In Fig. 5, the MR element 22 is exactly the same as Fig. 2, but the permanent magnet is
A permanent magnet 51 is magnetized in the same direction as the longitudinal direction. Therefore, like the MR element 22, the permanent magnet 51 also has a parallelogram shape. The purpose of this is to apply a bias magnetic field parallel to the cut groove 23 of the MR element 22, and according to the embodiment shown in FIG.
There is a new effect that the gradient of magnetization can be made more stable than in the case of FIG. 2, and other effects are the same as in FIG.

Figure 6 shows the cut groove angle θ of the MR head according to the present invention.
6 is a diagram showing the relationship between output level and secondary distortion level, 61 is a characteristic curve of the output level, and 62 is a characteristic curve of the secondary distortion level. The output level is highest near θ-45 degrees, and the second-order distortion level is lowest near θ=30 degrees. From this, if the cut groove angle θ is set in the range of 20 to 60 degrees, the sensitivity decrease will be within 5 dB and the second-order distortion level will be 4.
It can be seen that it falls within the range of 0 to 30 ciB and causes no practical problems.

In the above-described embodiment, the permanent magnet 24 or 51 was placed close to the rear of the MR element 22 (on the side opposite to the magnetic recording medium 6 side); however, this is MR.

This arrangement is for applying a bias magnetic field to the element 22, and is not limited to this arrangement. For example, multi-channel M
It goes without saying that in the R head, one permanent magnet may be placed behind each MR element to apply a bias magnetic field to all MR elements.

FIG. 7 is a structural diagram showing still another embodiment of the present invention.
(a) is a front view, (b) is a partial sectional view of (a), and the same parts as in FIG. 2 are indicated by the same symbols.

This is applied to the head, and is 71.7 in Figure 7.
2 is a high permeability magnetic layer (shield J#) made of nickel-iron alloy etc. with a film thickness of 2 μm, 75.74 is a film thickness of 03
It is a non-magnetic insulating layer of 8 tOz (silicon dioxide) or the like of μm. Other details are the same as in FIG. 2.

According to the embodiment shown in FIG. 7, the output at short wavelengths can be increased and the resolution of the MR head can be improved.

As explained above, according to the present invention, good characteristics can be obtained for a wide range of bias magnetic fields, and the strength and position of bias permanent magnets can be easily controlled, especially when multi-channel is used. This has the effect of significantly improving the dispersion of characteristics.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a conventional MR head, Fig. 2 is a structural diagram showing an embodiment of the R/IR head of the present invention, and Fig. 3 is a perspective view of a conventional MR head.
A diagram showing the relationship between the bias magnetic field of the head, the output level, and the secondary distortion level, FIG. 4 is a diagram showing the resistance change of the MR element with respect to the signal magnetic field of the MR head of FIG. 2, and FIG. FIG. 6 is a diagram showing the relationship between the cutting angle θ, the output level, and the secondary distortion level of the MR head according to the present invention, and FIG. It is a structural diagram showing an example of. 2.6... Electrode 6... Magnetic recording medium 21... Substrate 22... Magnetoresistive element (MR element) 25... Cut groove 24.51... Permanent magnet τ part゛□ Door-1 Figure 1 Figure 2 Figure (a) (shi) 3rd
Senno (Iasu stone eave* <oe) Fig. 4 H (Oe) Fig. 5 Fig. 6 Fig. 02σ30' 45° 6α Cut groove angle e Drawing 7 (cl) (shi) Continued from page 1 @ Inventor Arai Hitachi, Ltd. Home Appliance Research Laboratory, 292 Yoshida-cho, Totsuka-ku, Baidai Yokohama City

Claims (1)

[Scope of Claims] 1. In a magnetoresistive head equipped with a magnetoresistive element that senses changes in a magnetic field as changes in resistance value, a track width is provided at an end of the magnetoresistive element opposite to a magnetic recording medium side. A magnetoresistive head characterized in that it has a structure in which a cut groove is provided that is inclined with respect to the direction, and a bias permanent magnet is arranged at the rear of the end side of the magnetoresistive element where the cut groove is provided. . 2. The magnetoresistive head according to claim 1, wherein the cut groove has an angle of 20 to 60 degrees with respect to the track width direction. 3. The magnetoresistive head according to claim 1 or 2, wherein the bias permanent magnet is configured such that the magnetic field strength applied to the magnetoresistive element is 100e or more.