JPH0419810A - Magneto-resistance effect type head - Google Patents

Abstract

PURPOSE:To suppress the generation of Barkhausen noises and to prevent the fluctuation in output level by impressing the magnetic field similar to the diamagnetic field generated in the magneto-resistance effect type head (MR element) as current magnetic field. CONSTITUTION:The current magnetic field H generated by the current J 19 flowing in a current conductor layer 18 near the MR element 11 is impressed in the easy axis direction of the MR element 11 so as to negate the diamagnetic field. The current magnetic field to be impressed suffices, insofar as this current is larger than the current to negative the diamagnetic field generated in the MR element 11. The magnitude of the current J is adjustable by a power source. The MR head detects the signal magnetic field from a magnetic recording medium 17 moving right thereunder when the MR acts linearly. The MR element 11 has the monodomain structure in this way and does not generate the Barkhausen noises. The fluctuation in the output level of the MR element is averted.

Description

[Detailed Description of the Invention] [Summary] Regarding magnetoresistive heads, the present invention aims to prevent Barkhausen noise that occurs in the reproduced waveform of the magnetoresistive head and to avoid variations in the output level of the magnetoresistive element. In a magnetoresistive head that detects a magnetic field by a change in the resistance value of a magnetoresistive element disposed between two magnetic shields with a nonmagnetic insulating layer interposed therebetween, one of the magnetic shields is insulated. a conductor layer made of a magnetic material and provided between the insulating magnetic material and the non-magnetic insulating layer, one end of which is exposed to the outside of the insulating magnetic material;
and a member that supplies current to the conductor layer in order to apply a current magnetic field in the easy axis direction of the magnetoresistive element through the conductor layer.

[Industrial application field]

The present invention relates to a magnetoresistive head (hereinafter referred to as MR head).

In recent years, with the increase in the capacity of magnetic disk drives, which are external storage devices for computers, there has been a demand for high-performance magnetic heads. An MR head that can obtain high output regardless of the speed of the recording medium is attracting attention as one that satisfies this requirement.

[Conventional technology]

The MR head is a read-only magnetic head made of a ferromagnetic thin film (MR film), and uses the magnetoresistance effect, in which the electrical resistance of a ferromagnetic thin film made of permalloy or the like changes depending on an external magnetic field, to generate a signal magnetic field. This detects changes in electrical resistance as changes in electrical resistance. The element constituted by the ferromagnetic thin film is called a magnetoresistive element (hereinafter referred to as an MR element).

A conventional MR head has a structure as shown in FIGS. 2(a) and 2(b). 21 is a rectangular MR element, 22 is an extraction conductor layer, and 23a and 23b are magnetic shields.

The MR element 21 is patterned so that its longitudinal direction (y-axis direction) coincides with the direction of the easy axis of magnetization (hereinafter referred to as easy axis) of the MR film. The lead-out conductor layer 22 is
The MR element 21 is cut by a predetermined width in the longitudinal direction.
Both ends of the R element 21 are connected to the element. MR element 21
And the lead-out conductor layer 22 has two magnetic shields 23a.
, 23b (corresponding to the regeneration cap),
Magnetic shields 23a, 23b via nonmagnetic insulating layer 24
electrically insulated. Sense current 25 flows through the element through extraction conductor layer 22 and into a rectangular signal detection area 26 defined by MR element 21 and extraction conductor layer 22 . Then, the magnetic recording medium 27 moves under the head in the X-axis direction, and the MR head detects the signal magnetic field from the medium as a resistance change in the signal detection area 26.

Further, in this case, the sense current 25 is M
It was also used to linearize the reproduction of R-heads.

That is, the MR element 21 is placed close to one of the magnetic shields 23a, and a bias magnetic field is applied in the element height direction by the leakage magnetic field from the surface of the magnetic shield 23a magnetized by the sense current. This method is called the self-bias method. ) [Problem to be solved by the invention] In the shape of the conventional MR element 21, since the length of the MR element 21 is finite with respect to the magnetization direction of the easy axis (y-axis direction), a magnetic pole (N, A magnetic field (demagnetizing field) in the opposite direction to the magnetization direction was generated inside the element. For this reason, the MR element 21 has a magnetic domain structure divided into several magnetic domains as shown in FIG. was occurring.

On the other hand, in general, MR films have non-uniformities such as crystal grain boundaries, lattice defects, impurity inclusions, etc. due to incomplete film formation.

For this reason, in conventional MR heads, the domain wall moves while being caught in the signal magnetic field from the recording medium, causing magnetization rotation to become discontinuous, causing Barkhausen noise in the reproduced waveform, and causing the output level of the MR element to change. There was an issue with fluctuations.

[Failure to solve the problem]

In order to solve the above problems, the present invention provides an MR head that detects a magnetic field by a change in the resistance value of an MR element disposed between two magnetic shields with a nonmagnetic insulating layer interposed between the magnetic shields. one side of the body is an insulating magnetic material, a conductive layer is provided between the insulating magnetic material and the non-magnetic insulating layer, and one end thereof is exposed to the outside of the insulating magnetic material; A member for supplying current to the conductive layer so that a current magnetic field is applied in the easy axis direction was adopted.

[Effect]

By eliminating the demagnetizing field within the element using a current magnetic field from the MR element or the conductor layer, the element can be made into a single-axis structure without domain walls.

〔Example〕

FIG. 1(a) shows a sectional view of essential parts of an MR head according to an embodiment of the present invention.

As shown in the figure, the MR head has two magnetic shields 1
3a13b, the MR element 11 is arranged inside the lead-out conductor layer 12 via the nonmagnetic insulating layer 14.

Here, the MR element 11 is made of a ferromagnetic material such as a NiFe film, and the thickness tl is a thin film of 400 to 500 mm.
The width t2 is 3 μm, and the length t3 in the longitudinal direction is 50 to 100 μm.
It is set to about μm. Here, the shape of the MR element is either rectangular like the conventional MR element as shown in FIG. The shape does not matter as long as it is perpendicular. Then, it is excised with a predetermined width t4, and the MR
A lead-out conductor layer 12 having a width that matches the radiation t of the element.
and are connected at both ends of the signal detection area 16, as shown in FIG.

Due to the shape anisotropy of the MR element, the easy axis direction of the MR element 11 is the longitudinal direction. That is, the direction of the easy axis varies depending on the shape, and the direction of the easy axis generally coincides with the longer length direction, in this case the longitudinal direction. Here,
Since the MR element 11 is formed at its length or growth limit length with respect to its magnetization direction, a domain wall is generated inside the element, and a second
A demagnetizing field as shown in Figure (C) will be generated.

The lead-out conductor layer 12 is made of an Au film or the like. In this embodiment, it has the same radius t2 as the MR element as shown in FIG. 1, and is formed in a right-angled shape, but is not limited to such a shape. This is because it is sufficient that the sense current 15 flows through the signal detection region 16. Radiation t4 of signal detection area is 2 to 3 μm
That's about it.

The magnetic shield 13a is made of insulating magnetic NiZn ferrite material, and 13b is made of NiFe or ferrite material. These serve to enhance the reproduction resolution of the MR element 11 with respect to the signal magnetic field from the recording medium 17.

The MR element 11 and the extraction conductor layer 12 are arranged between two magnetic shields 13a and +3b, and both are electrically insulated from the magnetic shield via a nonmagnetic insulating layer 14 of SiO2 film or AI, O, film. The structure is as follows. M.R.
Element 11 is arranged inside nonmagnetic insulating layer 14 .

This is to block external magnetic fields or external currents other than the current conductor layer 118a.

A current conductor layer 118a is provided between the nonmagnetic insulating layer 14 and the magnetic shield 13a. The current conductor layer 118a is made of an Au film or the like similar to the lead-out conductor layer 12. This current conductor layer 118a is provided near the MR element 11.

Specifically, the distance t between the MR element 11 and the current conductor layer 118a in FIG. 1(a) is approximately several μm. Here, the reason why it is placed near the MR element 11 is to prevent current from flowing into the MR element due to contact with the MR element 11. As described above, the present invention has a structure in which a current conductor layer is placed in the vicinity of the element of a shield type MR head having a magnetic shield, and is not intended for, for example, a yoke type MR head. It is also different from the structure in which a coil or the like is wound around the element itself.

In this embodiment, the current conductor layer 118a serves as the current supply mechanism.
One end of the magnetic node 'r''l 3a is embedded in an insulating substrate together with the magnetic shield 13a, and the magnetic node 'r''l 3a is exposed to the outside on the side facing the recording medium 17. One end is the current conductor layer l1
18b, and the other end of the current conductor layer 118b is exposed during slider processing and becomes a current supply terminal. Here, the current conductor layer (2) does not have to extend in a direction perpendicular to the magnetic recording medium as in this embodiment, but may extend in a direction as shown in FIGS. 1(d) and 1(e). As will be described later, the object of the present invention can be achieved if the current magnetic field H is applied in the easy axis direction of the MR element 11 through the current conductor layer 1) 8a. Here, FIG. 1(d) shows the current conductor layer n18b.
Figure 1(e) shows the current conductor layer II+8b extended horizontally.

Further, if the substrate A is a conductor (for example, Al2O, TiC, etc.), there is no need to provide the current conductor layer II+8b independently as long as a portion to be connected to the current conductor layer T18a is provided. In this case, the substrate A is provided with a power supply terminal. Similarly, the current magnetic field H is applied to the MR element 11 by the current conductor layer 118.

FIG. 1(b) shows a principle diagram of the MR head of the present invention.

Current J1 flowing through current conductor layer 18 near MR element 11
The current magnetic field H generated by 9 is applied in the easy axis direction of the MR element 11 in an attempt to cancel the demagnetizing field. However,
The applied current magnetic field only needs to be strong enough to cancel out the demagnetizing field generated in the MR element 11. The magnitude of the current J can be adjusted by a power source (not shown).

As described above, the present invention is characterized in that one end of the current conductor layer 118a is exposed to the outside of the magnetic shield 13a. When connecting the power supply to the current conductor layers I and ■, the magnetic shield 13a
This is because it is preferable that it not be between 13b and 13b.

The sense current 15 flows into the signal detection region 16 of the MR element 11 through the extraction conductor layer 12. This state is clearly shown in the main part perspective view of the MR head in FIG. 1(C). Then, the MR head detects a signal magnetic field from the magnetic recording medium 17 moving directly below by linearly operating the MR head using the above-described self-bias method. At this time, the MR element 11 has a single magnetic domain structure according to the above-mentioned inventive principle, and no Barkhausen noise is generated. Furthermore, fluctuations in the output level of the MR element can be avoided.

As a first example of the manufacturing process of the MR head according to the embodiment of the present invention, as shown in FIG.
A block-shaped magnetic shield 13a (for example, NiZ
There is a method of stacking layers one after another, such as n, etc., and then cutting them at the machined surface.

〔Effect of the invention〕

As explained above, according to the present invention, by applying a magnetic field similar to the demagnetizing field generated in the MR element as a current magnetic field, the MR element is made into a single magnetic domain structure without domain walls, suppressing the occurrence of Barkhausen noise, and Prevents fluctuations in the output level of the MR element.

[Brief explanation of drawings]

FIG. 1(a) is a sectional view of essential parts of an MR head according to an embodiment of the present invention, FIG. 1(b) is a principle diagram of the MR head of the present invention, and FIG.
c) is a perspective view of the main parts of an MR head according to an embodiment of the present invention, FIG. 1(d) is a diagram of an embodiment of the present invention in which the arrangement of the current conductor layer 2 is changed, and FIG. 1(e) is a diagram of the current conductor layer. Figure 1(f) is a diagram illustrating the process of creating an MR head according to an embodiment of the present invention; Figure 2(a) is a diagram of a conventional MR head. 2(b) is a perspective view of essential parts showing a conventional MR head. FIG. 2(C) is a MR element magnetic domain structure in the conventional MR head. In the figure, 1 is an MR element, 2 is an extraction conductor layer, 3a is a magnetic shield, 3b is a magnetic shield, 4 is a non-magnetic insulating layer, 5 is a sense current, 6 is a signal detection area, 7 is a magnetic recording medium, 8 is a magnetic recording medium Current conductor layer, 8a is a current conductor r@I, 8b is a current conductor layer ■, 9 is a current J, 1 is an MR element, 2 is an extraction conductor layer, 3a is a magnetic shield, 3b is a magnetic shield, 4 is a non-magnetic insulation 25 is a sense current, and 26 is a signal detection region.

Claims (1)

[Claims] A magnetoresistive element (
11) In a magnetoresistive head that detects a magnetic field by a change in resistance value, one of the magnetic shields (13a
) is an insulating magnetic material, and a conductive layer (18a) is provided between the insulating magnetic material (13a) and the non-magnetic insulating layer (14), and one end thereof is exposed to the outside of the insulating magnetic material (13a).
), and the magnetoresistive element (11) by the conductor layer (18a).
) for applying a current magnetic field in the easy axis direction of the conductor layer (18a).