JPH03134810A - Magneto-resistance effect type head - Google Patents

Abstract

PURPOSE:To improve output and to reduce noise by forming a magnetic circuit on one side, which faces to a recording medium, of a differential-type magneto- resistance element having three terminals in the sensor part of the element in order to introduce leaked magnetic field from the recording medium. CONSTITUTION:A magnetic gap film comprising an insulating material is formed on a desired substrate such as soft magnetic chromite which works as a magnetic shield or a nonmagnetic substrate equipped with a magnetic shield film. First, a Permalloy thin film having magneto-resistance effect is formed on the substrate, and successively a Nb film is formed by vapor deposition as a shunting film for applying a bias magnetic field. The Nb/Permalloy double- layer film is subjected to fine processing, on which an insulating film for a magnetic gap is provided, and further a magnetic shield material is provided to constitute the magnetic head. By this constitution, output of the head can be improved and noise in electrodes can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetoresistive head for recording and reproducing used in a magnetic storage device.

[Conventional technology]

The conventional differential magnetoresistive head was published in Japanese Patent Application Laid-open No. 61-19.
As described in No. 9684, the structure was such that a magnetoresistive film was provided with three electrode lead wires. The differential magnetoresistive head has advantages such as linearization of the output waveform and (3) effective increase in bias magnetic field strength, but as the track width of the head becomes narrower, one of the three electrodes
Since the central electrode part does not function effectively as a magnetically sensitive film, there is a drawback that the effective output drops when the track becomes narrow.

[Problem to be solved by the invention]

The above-mentioned conventional technology does not take into consideration the non-magnetically sensitive portion of the central electrode portion of the differential magnetoresistive head, and does not effectively utilize the magnetic field penetrating from the magnetic recording medium.

The present invention improves the output of a differential magnetoresistive head by effectively utilizing the magnetic field from the recording medium that enters the non-magnetically sensitive part, that is, the electrode part, and also improves the output of the differential magnetoresistive head. It is an object of the present invention to provide a differential magnetoresistive head in which the influence of a magnetic field that does not contribute to the output, that is, noise, is reduced, and the crack width is strictly set from 1 to 1.

[Means to solve the problem]

”-In order to achieve a magnetic field effect, it is preferable to install a magnetic path 5 (4) close to the magnetically sensitive part 1 of the differential magnetoresistive element shown in FIG. In order to facilitate perpendicular penetration into the section 1, magnetic paths 7 and 8 are installed on the opposite side of the surface 6 facing the recording medium with the magnetically sensitive section in between.

[Effect]

In FIG. 1, the magnetic field entering the magnetic path tip 6 facing the recording medium (not shown) passes through a magnetic path whose width becomes wider as it approaches the magnetically sensitive part 1 of the magnetoresistive element, and passes through the magnetically sensitive part 1 of the magnetoresistive element. 1
to invade. The magnetic field that has entered the magnetic sensing part 1- further passes through magnetic paths 7 and 8 installed on the side opposite to the medium facing surface. 1st
In the figure, if magnetic paths 7 and 8 are not installed,
As the penetrating magnetic field expands, the strength of the magnetic field penetrating into the magnetic sensing part decreases, reducing the output of the magnetoresistive effect, and the noise increases because the penetrating magnetic field does not have a direction perpendicular to the magnetic sensing part. do.

In order to make the penetrating magnetic field penetrate into the magnetically sensitive part more efficiently, as shown in FIG. (5) The penetrating magnetic field enters the two magnetically sensitive parts of the magnetoresistive element in a concentrated manner. In order to further concentrate the penetrating magnetic field, the magnetic path may be separated into two as shown in FIG. 3, 10.11.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

Soft magnetic cramite that acts as a magnetic shield.

The desired substrate (such as a non-magnetic substrate with a magnetic shielding film)
First, a permalloy thin film exhibiting a magnetoresistive effect was deposited to a thickness of about 50 nm by vacuum evaporation on the substrate surface on which a magnetic gap film (not shown) made of an insulating material such as An 20s or Si 02 was formed. Then, Nb is deposited as a shunt film for applying a bias magnetic field. The Nb/permalloy two-layer film produced as described above is microfabricated as shown in Figure 1, a magnetic gap insulating film (not shown) is formed thereon, and the same magnetic shielding material (not shown) as described above is formed. (not shown) was installed to form a magnetic head.

At this time, if the 1-rack width a shown in FIG.
In order to drive with an amount of current on the order of cnY, a minimum width of 5 μm is required as the center electrode width, so the width of the sensor portion into which the signal magnetic field from the recording medium enters is 5 μm or less.

On the other hand, in the head equipped with the magnetic path shown in the example,
It absorbs the signal magnetic field from the entire track width of the recording medium,
Since almost 100% of this signal magnetic field can be input into the sensor section of the differential magnetoresistive element, there is no effect of reduction in the effective 1-rack width of the sensor section due to the electrodes. Therefore, when the track width is about 5 to 20 μm, an output that is 2 to 5 times higher than that of a conventional differential magnetoresistive element without a magnetic path can be obtained. Further, since it is possible to reduce the intrusion of a signal magnetic field into the electrode section compared to a conventional differential magnetoresistive head, it is also possible to reduce noise caused by the electrode section.

〔Effect of the invention〕

As explained in the above embodiments, the present invention can absorb the signal magnetic field from the entire track width of the recording medium by forming a magnetic path in the differential magnetoresistive element (7), thereby increasing the head output. is measured. This effect is particularly effective as the recording I-rack width becomes narrower, and when the track width is several tens of micrometers or less, the output increases by 2 to 5 times or more.

[Brief explanation of the drawing]

FIG. 1 is a plan view of essential parts of a magnetic head according to an embodiment of the present invention;
Fig. 2 is a shoulder view of the main part of the embodiment shown in Fig. 1 in which the magnetic path section has a recess, and Fig. 3 shows the embodiment in which the magnetic path section shown in Fig. 1 is separated into two parts. FIG. 1... Magnetoresistive element, 2, 3.4... Electrode/lead,
5.7.8...Magnetic path. (8)

Claims (1)

[Claims] 1. In a magnetoresistive device that reproduces recorded signals from a magnetic recording medium using the magnetoresistive effect, there is provided a differential magnetoresistive element having three terminals in a sensor section. A magnetoresistive head characterized in that a magnetic path for guiding a leakage magnetic field from a recording medium is formed on a surface facing the recording medium. 2. A magnetoresistive head according to claim 1, wherein the magnetic path is made of a thin film of high magnetic permeability material. 3. In claim 1, the planar dimensions of the magnetic path are close to the recording track width on the surface facing the recording medium, and close to the width of the differential magnetoresistive element in the vicinity of the differential magnetoresistive element. A magnetoresistive head characterized by: 4. The magnetoresistive head according to claim 1, having a structure in which a magnetic path is also provided at the rear of the sensor so that the magnetic field entering from the magnetic path preferentially enters the magnetoresistive sensor section. 5. The magnetoresistive head according to claim 1, wherein the magnetoresistive thin film forming the magnetoresistive sensor and the thin film forming the magnetic path are on the same plane or in a similar position. 6. A magnetoresistive head according to claim 1, wherein the differential magnetoresistive element is made of a single layer of a magnetoresistive thin film, and a thin film for applying a bias magnetic field is disposed adjacent thereto. 7. A magnetoresistive head according to claim 1, wherein the magnetoresistive element is a two-layer film integrated with a conductor thin film for applying a bias magnetic field. 8. The magnetoresistive element according to claim 1, wherein the film thickness of the magnetic path is greater than the thickness of the magnetoresistive film of the magnetoresistive element portion. 9. A magnetoresistive head according to any one of claims 1 and 3, characterized in that the dimension of the magnetic path from the surface facing the recording medium toward the differential magnetoresistive element changes continuously. 10. A magnetoresistive head according to claims 1 and 2, wherein the ferromagnetic material forming the magnetic path is made of permalloy, Fe alloy, Co-based amorphous magnetic material, or sendust. 11. The magnetoresistive head according to claim 1, further comprising a magnetic shield made of ferrite. 12. In claim 1, the magnetic shield is permalloy,
A magnetoresistive head comprising a Co amorphous magnetic material and an Fe alloy.