JPH06325327A - Magnetoresistance effect type thin film magnetic head - Google Patents

Abstract

PURPOSE:To suppress the generation of Barkhausen noise and to obtain good reproducing output by forming yokes in a such a manner that the yokes are made thin near the magnetoresistance effect element and thick in other area. CONSTITUTION:The substrate 1 consists of a magnetic material having high magnetic permeability such as Ni-Zn ferrite, and insulating layers 2, 3 consist of SiO2, etc. A conductive material 4 such as Al to apply a bias magnetic field on a MR element 5 is disposed between these layers. The MR element 5 is a Ni-Fe allay thin film and is formed into a shape of 0.05mum thick, 10mum wide, and 70mum long along the track width direction. A first yoke 7 and a second yoke 8 consist of Ni-Fe alloy thin films of 1mum thickness. The first and second yokes 7, 8 are processed to have 0.05mum thickness in the area within 5mum distance from the MR element. The insulating layer 6 acts as an electric insulating layer between the MR element 5 and the first or second yokes 7, 8, and further, it acts as a magnetic gap between the lower yoke and the first yoke 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive thin film magnetic head (hereinafter referred to as M
R head).

[0002]

2. Description of the Related Art As a conventional MR head, the one shown in FIG. 2 is known. This is called a yoke type MR head, and has a structure in which the MR element is separated from the magnetic recording medium during actual use, and a yoke made of a magnetic material for guiding the signal magnetic flux from the magnetic recording medium to the MR element is arranged.

FIG. 2 is a sectional view of the yoke type MR head in a direction perpendicular to the track width direction. Substrate 1 is Ni-Z
It is a high-permeability magnetic material such as n-ferrite and Mn-Zn ferrite, and serves as the lower yoke. A conductor 4 for applying a bias magnetic field to the MR element 5 is arranged between the insulating layers 2 and 3. For the MR element 5, a Ni-Fe alloy thin film or the like is used. The first yoke 7 and the second yoke 8 which serve as magnetic paths for guiding the signal magnetic flux recorded on the magnetic recording medium to the MR element 5 are usually N having a thickness of 0.5 to 1 μm.
An i-Fe alloy thin film or the like is used. The insulating layer 6 serves as an electrical insulating layer between the MR element 5, the first yoke 7 and the second yoke 8, and a magnetic gap between the lower yoke and the first yoke 7.

In the above-mentioned MR head, magnetic anisotropy having an easy axis of magnetization is usually provided in the track width direction of the MR element, and the MR element is used in a single magnetic domain state. M
The reproduction of the R head is to detect the change in the resistance value of the MR element caused when the magnetization of the MR element is rotated by the signal magnetic flux from the magnetic recording medium.

[0005]

However, the conventional yoke type MR head has a problem that magnetic domains are generated in the MR element and the magnetic domains discontinuously move to generate Barkhausen noise in the reproduced signal. . Disturbance in the magnetic anisotropy of the MR element can be cited as a cause for generating magnetic domains in the MR element. As a factor that disturbs the magnetic anisotropy of the MR element, the films forming the first yoke and the second yoke have internal stress, and stress is applied to the MR element from the yoke.
It can be mentioned that stress-induced magnetic anisotropy is imparted to the MR element by the inverse magnetostriction effect and the magnetic anisotropy in the track width direction is disturbed. The yoke film is formed of Ni-Fe alloy or the like by sputtering, vapor deposition, plating or the like, but the film has an inherent internal stress in any manufacturing method, and it was difficult to reduce this internal stress. .

[0006]

In order to solve the above-mentioned problems, the present invention is characterized in that the thickness of the yoke is thin near the MR element and thick in other portions.

[0007]

By reducing the stress applied from the yoke to the MR element, the stress-induced occurrence of magnetic anisotropy is reduced, and the disturbance of the magnetic anisotropy of the MR element in the track width direction is suppressed. For that purpose, it is conceivable to dispose the yoke away from the MR element. However, when the yoke is arranged away from the MR element, there arises a problem that the signal magnetic flux from the magnetic recording medium guided to the yoke hardly reaches the MR element and the reproduction output is lowered. Therefore, in the present invention, the yoke is M
The yoke is arranged without being separated from the R element, and the thickness of the yoke is reduced only in the vicinity of the MR element to reduce the stress applied to the MR element from the yoke. If the yoke thickness is, for example, 0.05 μm only in the vicinity of the MR element and 1 μm in other portions, the stress can be reduced to about 1/20. The reproduction output is reduced due to the thin yoke.
Since it is only in the vicinity of the R element, it hardly occurs.

According to the present invention, it is possible to obtain the yoke type MR head which reduces the stress from the yoke, which has a detrimental effect on the MR element, and has less Barkhausen noise.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of a yoke type MR head according to the present invention and is a sectional view in a direction perpendicular to the track width direction. The substrate 1 is a high-permeability magnetic material such as Ni-Zn ferrite and serves as a lower yoke. Insulating layer 2,
The insulating layer 3 is made of SiO ₂ or the like, and a conductor 4 such as Al for applying a bias magnetic field to the MR element 5 is provided between them.
Are placed. The MR element 5 is a Ni—Fe alloy thin film or the like, and is processed into a shape having a thickness of 0.05 μm, a width of 10 μm, and a length of 70 μm in the track width direction. The first yoke 7 and the second yoke 8 are Ni-Fe alloy thin films having a thickness of 1 μm, etc., and have a thickness of 0.05 μm in the range of 5 μm near the MR elements of the first yoke 7 and the second yoke 8. Is processed.
The insulating layer 6 serves as an electrical insulating layer between the MR element 5, the first yoke 7 and the second yoke 8, and a magnetic gap between the lower yoke and the first yoke 7.

When the magnetic recording medium is reproduced by the head according to the present invention shown in FIG. 1, the characteristics of the conventional head having the thickness of the first yoke 7 and the second yoke 8 shown in FIG. In comparison, Barkhausen noise was small, and the reduction in reproduction output was within 1 dB. Also, the first yoke and the second
The thickness of the yoke is 1 μm, and the MR element and the yoke are 2 μm.
Barkshausen noise is as small as that of the head of the present invention in the heads separated by m, but the reproduction output is reduced by 10d.
It was B or more.

[0011]

As described above, according to the MR head of the present invention, it is possible to reduce the occurrence of stress-induced magnetic anisotropy in the MR element portion, and it is possible to suppress Barkhausen noise. It is possible to obtain a proper reproduction output.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of a magnetoresistive thin film magnetic head according to the present invention.

FIG. 2 is a sectional view of a conventional magnetoresistive thin film magnetic head.

[Explanation of symbols]

 1 Substrate 2, 3, 6 Insulation Layer 4 Conductor 5 Magnetoresistive Element 7 First Yoke 8 Second Yoke

Claims (1)

[Claims] 1. A magnetoresistive effect thin-film magnetic head provided with a yoke serving as a magnetic path for guiding a signal magnetic flux generated from a magnetic recording medium to a magnetoresistive effect element, wherein the yoke has a thickness near the magnetoresistive effect element. A magnetoresistive thin-film magnetic head characterized by being thin and thick in other portions.