JPH01264622A - Magneto-resistance effect type magnetic head - Google Patents

Abstract

PURPOSE:To decrease the noises generated by adjacent tracks by parting a magnetic head element except in a track part from a sliding surface. CONSTITUTION:A magneto-resistance effect type element 2 is curved with respect to the sliding surface 1 so that the part 21 except the track width is parted from the sliding surface 1. A magnetic shielding layer 3 consisting of a soft magnetic material is provided between the surface 1 and the element 2. The Barkhausen noise output increases with an increase in theta if the angle between the curved part of the element 2 and the sliding surface is designated as theta in this constitution. On the other hand, the crosstalk noise output decreases with an increase in the theta. Any noise outputs change with the theta in such a manner and the noises of both can be successfully decreased by setting the theta to a 5-40 deg. range. The similar effect is obtainable even if the layer 3 is not formed; however, the crosstalk noises increase in such a case. The better result is, therefore, obtd. when the layer 3 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to high-density magnetic recording, and particularly to a magnetoresistive magnetic head with high reproduction sensitivity.

[Conventional technology]

A magnetoresistive magnetic head (hereinafter referred to as MR head), which utilizes the magnetoresistive effect of a ferromagnetic metal thin film, has a reproduction output that does not depend on the running speed of the recording medium and can easily narrow the track. It is attracting attention as a reproducing head for high-density magnetic recording. However, in MR hehe,
The narrowing of the track increases Barkhausen noise caused by irregular domain wall movement within the MR element. This Barkhausen noise deteriorates reproduction sensitivity and is one of the factors that prevents narrowing of the track.

In order to reduce this noise, it is effective to make the MR element have a single magnetic domain structure.As a method, the shape of the MR element can be changed to a stripe shape with a large aspect ratio or a closed magnetic circuit structure like a picture frame. It has been proposed that

Such techniques are discussed in Journal of the Japan Society of Applied Magnetics, Vol. 11, No. 2 (1987), pp. 95-98.

[Problem to be solved by the invention]

Although the above technology can reduce Barkhausen noise,
The length of the MR element becomes longer than the track width. Therefore, there is a problem in that crosstalk between adjacent tracks occurs, causing noise.

An object of the present invention is to provide a magnetoresistive head that reduces Barkhausen noise and at the same time reduces crosstalk noise caused by adjacent tracks.

[Means to solve the problem]

The above purpose is to expose only the track width portion to the sliding surface in an MR element having a length longer than the track width, and gradually move the MR elements on both sides of the track width away from the sliding surface to create a curved shape. This is achieved by That is, by increasing the distance between the MR element and the medium in areas other than the track width, the magnetic flux flowing from the rack to the adjacent 1 is drastically reduced, and thus crosstalk noise is reduced.

Further, crosstalk noise can be further reduced by providing a soft magnetic material serving as a magnetic shield layer between the MR element and the sliding surface.

[Effect]

The present invention will be explained in detail using FIGS. 2 and 3. Second
The figure is a plan view showing the structure of the MR head.

The MR element 2 is curved with respect to the sliding surface 1, and the portion 21 other than the track width is separated from the sliding surface 1.

Further, a magnetic shielding layer 3 made of a soft magnetic material is provided between the sliding surface and the MR element. Both ends 21 of the MR element are covered with electrodes 4.

In the figure, the angle between the curved portion of the MR element and the sliding surface is assumed to be 0. FIG. 3 shows a magnetic head manufactured using the above MR element, and the noise during reproduction was investigated using θ as a parameter. The circle indicates the Barkhausen noise output, which increases as θ increases. This is considered to be because as 0 increases, the shape anisotropy of the MR:M element decreases, making it easier for magnetic domains to occur. On the other hand, the mark X indicates the crosstalk noise output, which decreases as θ increases. This means that as θ increases, both ends of the MR element become
It is thought that noise from adjacent tracks is reduced because the tracks are separated from the sliding surface. In this way, both noise outputs change with respect to 0, and in order to reduce both noises, it is better to set θ to a range of 5° to 40', more preferably around 20°. I understand.

Note that even in the case where the magnetic shielding layer 3 shown in FIG. 2 is not provided, similar results can be obtained, but crosstalk noise increases. Therefore, it is preferable to provide a magnetic shielding layer.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. This figure (a) is a perspective view of the MR head, and (b) is a perspective view of the MR head.

(c) shows cross-sectional views along AA' and BB', respectively. In the figure, an MR element 2 is sandwiched between upper and lower magnetic shield layers 31 with an insulating layer 5 in between. The width of the MR element was 40 μm, and only the central 10 μm portion was exposed to the sliding surface, and both sides were set back at an angle of 15° with respect to the sliding surface. Further, the height of the element is 8 μm. Here, the magnetic shield layer 31 is made of permalloy with a thickness of 2 μm. In addition, the MR element 2 is made of permalloy with a film thickness of 500 mm and a film thickness of 20 mm.
It consists of a Ti film of 0.00 people. The electrode pattern 4 has a film thickness of 20
Consists of 00 Au. Here, the bias magnetic field necessary for the operation of the MR element is applied by a current shunted to the Ti film in the element. (Shunt bias method).

Cross 1-1 noise was compared between the reproducing head manufactured according to this example and the reproducing head having a rectangular MR element having a conventional structure, that is, O=0°. As a result, it was found that this example had lower noise by about 2 dB and was more effective in reducing noise.

FIG. 4 shows another embodiment of the invention. In the same figure (a),
It is a perspective view of MR head, and (b) and (C) are sectional views of AA' and BB', respectively. M1-<The width of element 2 is 40 μm and the height is 8 μm. center length 1
Only a 0 μm portion was exposed on the sliding surface, and both sides were set back at an angle of 15° with respect to the sliding surface. Moreover, between this sliding surface and the MR element end 21, there is a magnetic shield layer 3].
There is a shield layer 32 consisting of parts.

Here, the MR element 2 is made of permalloy with a thickness of 500 strands and a Tj film with a thickness of 2000 strands, as in the j-th embodiment. Further, the electrode 4 is made of an Aυ film with a thickness of 2000. The magnetic shield layer is made of permalloy with a thickness of 1 μm,
A shield layer 32 is formed by processing a portion of the shield layer. Further, although a permalloy film is used as the shield layer, other soft magnetic films such as FeA Q b j alloy or co-based amorphous alloy can also be used. Furthermore, when a ferrite substrate such as M n or -Z n is used as the substrate, the substrate can also be used as a magnetic shield layer.

Although a shunt bias method was used as the bias method for the above head, other known bias methods such as barber ball method, permanent magnet bias method, soft film bias method, and a combination of these bias methods can also be used. .

Noise during reproduction was measured for a head having a linear MR element having the same dimensions as the above-mentioned MR element 2, and for the head according to this example. As a result, it was found that the crosstalk noise of the head of this example was about 4 dB lower and was effective in reducing noise. Additionally, Barkhausen noise was hardly observed, and no significant difference was observed between the two heads.

In the above embodiments, each of the MR cords 2 had a curved rectangular shape, but by tilting the MR element end 22 with respect to the sliding surface 1, as shown in FIG. It can also be applied to an MR element with Further, in this embodiment, the same effect can be obtained even if the outline of the MR element is made into a straight line or by using a gentle arc-shaped curve.

〔Effect of the invention〕

According to the present invention, since the MR elements other than the track portion can be moved away from the sliding surface, noise caused by adjacent tracks can be reduced. Furthermore, by providing a soft magnetic layer between the sliding surface and the end of the MR element other than the magnetic sensing portion, noise from adjacent tracks can be more effectively reduced.

[Brief explanation of the drawing]

FIG. 1 is a perspective view and a sectional view of a magnetic head showing an embodiment of the present invention, FIG. 2 is a plan view of an MR element explaining the present invention in detail, and FIG. 3 is a noise output showing the effects of the present invention. 4 is a perspective view and a sectional view of a magnetic head showing another embodiment of the present invention, and FIG. 5 is a plan view of an MR element showing another embodiment of the present invention. be. DESCRIPTION OF SYMBOLS 1... Sliding diagram, 2... MR element, 4... Electrode pattern, 5... Insulating layer, 21... MR element end part, 31
...Magnetic shield layer, 32... Shield layer.

Claims (1)

[Claims] 1. In a magnetoresistive magnetic head, the shape of a magnetoresistive element serving as a magnetic sensing part is curved with respect to a sliding surface,
A magnetoresistive magnetic head characterized by having only a portion exposed to the sliding surface. 2. The magnetoresistive magnetic head according to claim 1, wherein the angle between the sliding surface and the curved portion of the magnetoresistive element is between 5° and 40°. 3. The magnetoresistive magnetic head according to claim 1, further comprising a soft magnetic layer between the sliding surface and the magnetoresistive element except for the portion exposed to the sliding surface. 4. The soft magnetic layer between the sliding surfaces of the magnetoresistive element is
2. The magnetoresistive magnetic head according to claim 1, wherein the magnetoresistive head is magnetically coupled to a soft magnetic layer at both ends or one side of the magnetoresistive element.