JPS5984328A - Magneto-resistance effect type film head - Google Patents

Abstract

PURPOSE:To eliminate the asymmetry of a reproduced waveform, by arranging conductors to two gaps formed by two shield layers and a magnetoresistance effect element and making a bias current to flow in the opposite direction. CONSTITUTION:An insulating layer (SiO2) 8A, conductor (Al, Au, etc.) 3a, insulating layer 8B, magnetoresistance effect (MR) element (Fe-Ni alloy) 2, conductor 3B, and shield layer 4 are successively formed on a shield plate 1 made of a high-magnetic-permeability material by sputtering, evaporation, etc. When the distances, namely the length of the gaps between the MR element 2 and the shield layer 1 and between the MR element 2 and the shield layer 4 are made equal and a bias magnetic field is impressed upon the MR element 2 by making an electric current to flow to the conductors 3a and 3b in the opposite direction, the asymmetry of a reproduced waveform can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION This invention provides ferromagnetic I? The present invention relates to a magnetic head that utilizes the magnetoresistive effect of a film, and particularly to a configuration for applying a bias that applies a magnetic field to a magnetoresistive thin film element.

The thin-film read head, which utilizes the magnetoresistive effect of the ferromagnetic metal S film, has high sensitivity, the playback output does not depend on the relative speed with the medium, and high-frequency operation is possible.Furthermore, it has been developed using microfabrication technology such as IC. It has attracted attention because it can be produced in bulk and is being actively researched.

FIG. 1 shows a configuration for explaining the principle of thin film deposition using a current bias method using a magnetoresistive element (hereinafter referred to as MR hydrogen).

A thin film MR element 2 is arranged close to the recording medium 7. Electrodes 5 are provided at both ends of the MR element 2,
A DC voltage is applied to this electrode, so that a current (1) flows in one direction of the MR element 2 (-ζ). Furthermore, there is a bias conductor 3 for not applying a bias magnetic field to the MR hydrogen. or,
In order to improve the resolution in the short wavelength region, shields N1 and 4 made of high transmission rate grinding holes are installed on both sides of the MR hydrogen.

The operating principle of the magnetoresistive type "a-crotch belly button 1" constructed in this way will be explained.

Place the MR element 2 close to the recording medium 7 -B, MI? A DC voltage is applied to electrodes provided at both ends of the element, causing a constant current to flow through the MR element 2. At this time, the operating characteristics of the MR element 2, which detects the 11L resistance change of the MR element 2 due to the y-direction signal magnetic field component try from the recording medium as a voltage change across the electrodes 5, are as shown in FIG.

In order to linearly change the operating characteristics, it is necessary to apply a bias magnetic field He to the MR element 2 so that the operating point is near the entry point. As methods for applying the bias magnetic field, there are two main methods: passing a current through the bias conductor 3, and using a permanent magnet film. FIG. 3 is a sectional view of a magnetoresistive thin film head showing a specific structure, and the same reference numerals as in FIG. 1 do not indicate the same members. Note that numbers 8, 9, and 10 are insulating layers that insulate the shield N1, the MR element 2, the bias conductor 3, and the shield layer 4.

The MR element 20 resolution is from the MR element 2 to the shield layer 1,
The distance to 4 is determined by 1tll1g++g2. That is, g
+ consists of an insulating film 8 such as 5i02 between the shield layer 1 and the MR element 2, and g2 consists of the MR element 2 and the bias conductor 3.
This is the sum of the insulating film 9 such as 5i02 between them, the bias conductor 3, and the insulating film 10 such as SiO□ between the bias conductor 3 and the shield layer 4.

The thickness of the insulating layers 7 and 8.9 is about 0.3 μm, and the thickness of the bias conductor 3 is about 0.4 to 0.5 μm, which is 38 m1.
Gap g2cwJ, pm becomes ~gap g+ Gap g2 becomes considerably larger. In this way, if the gear g+ and the gap g2 are not equal, the reproduced waveform will be
The disadvantage is that the peak shifts toward the larger gap.

This invention was made in view of the above-mentioned drawbacks, and its purpose is to provide a magnetoresistive thin film head that equalizes the gap length gltg2 between the MR hydrogen and the shield and eliminates the asymmetry of the reproduced waveform. is to provide.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

FIG. 4 is a cross-sectional view of the magnetoresistive J-shaped thin film head of the present invention, and the same reference numerals shown in FIG. 3 indicate the same members. In FIG. 4, the first
Using the shield plate 1 as a medium, spankling on this,
Insulating layer 8A made of 5i02 with a thickness of 0.3 μm by vapor deposition etc.
A first conductor 38 for bias application is formed on E of the insulating layer 8A using a conductive material such as A11%Ca%Au to a thickness of 0.2 pm by sputtering, vapor deposition, etc. has been done. An insulating layer 8B is formed on the first conductor 3Δ in the same manner as the insulating layer M8A, and this insulating layer 8B has a thickness of 50 mm.
An MR element 2 of Fe--Ni alloy is formed. M.R.
On top of the element 2 are an insulating layer 9 (thickness 0.3 μm), a second conductor 3B (thickness lO 12 μm) for bias application, and an insulating layer M
9 (thickness 0.3+um) is formed in the same manner as the insulating layer 8A and the first conductor 38, and on the insulating layer 9, re-Ni is formed.
The shield layer 4 is formed by forming a high permeability magnetic material such as the above by sputtering, vapor deposition, etc. to a thickness of about 1 μm.

And a first conductor 3A for bias application, a second conductor 3
Since the configuration is such that a current is passed in the opposite direction to B and a bias magnetic field is applied to the MR element 2, the MR
The distance between the element 2 and the shield plates (layers) 1 and 4, that is, the gap length gl9g11, can be made approximately equal.

As explained above, the present invention provides a magnetoresistive element made of a ferromagnetic thin film, which is provided on both sides with nonmagnetic layers interposed therebetween.
In a magnetoresistive head equipped with a sealing layer made of a high permeability magnetic material, a conductor is placed in each of the two gaps formed by the shielding layer and the magnetoresistive element, and the conductors are placed in opposite directions. Since the configuration is such that a bias magnetic field is applied to the magnetoresistive element by passing a current in the direction, the reproduced waveform is symmetrical and has little distortion.

[Brief explanation of the drawing]

Figure 1 shows the magnetic navel 1' of current bias using MR hydrogen.
Figure 2 is an operational waveform diagram, Figure 3 is a cross-sectional view of a conventional magnetic effect thin film head without showing an example of its length, and Figure 4 is a diagram explaining the principle of
The figure is a sectional view showing an embodiment of the magnetic effect type VRI film (node) of the present invention.

Claims (1)

[Claims] A non-magnetic layer is placed on both sides of a magnetoresistive element made of a ferromagnetic thin film.
Established through support. In a magnetoresistive head equipped with a shield layer made of a highly permeable magnetic material, a conductor is placed in each of the two gaps formed by the shield layer and the magnetoresistive element, and the conductors are placed in opposite directions. A magnetoresistive thin film head is characterized in that a bias magnetic field is applied to a magnetoresistive element by flowing a current in the direction of the magnetoresistive element.