JPS6325817A - Magneto-resistance effect type magnetic head - Google Patents

Abstract

PURPOSE:To set the bias magnetization in a magneto-resistance (MR) magnetic sensing part to an optimum state in all of its area by specifying the practical arrangement constitution of an electrode, which gives a sense current to the MR magnetic sensing part, and a bias magnetic field impressing means. CONSTITUTION:An MR magnetic sensing part 2, which is so arranged that a sense current Is flows in the same direction as a signal magnetic field Hs, and a pair of electrodes 7 and 8 which flow the sense current Is to the magnetic sensing part 2 are provided. One electrode 7 is provided with a part 7A, which overlaps one end of the magnetic sensing part 2 and is electrically connected there, and a part 7B which is extended in the direction approximately orthogonal to the essential supply direction of the sense current Is in the magnetic sensing part 2 and is electrically insulated from the magnetic sensing part 2. The magnetic sensing part 2 is formed on the first magnetic substrate 1 with an insulating layer 11 between them by sticking. The unstable mutual influence between the magnetic field due to the front electrode 7 to the MR magnetic sensing part 2 and the bias magnetic field is avoided to stably obtain a proper bias magnetization state in the MR magnetic sensing part 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetoresistive (hereinafter referred to as MR) effect type magnetic head.

[Summary of the invention]

The present invention improves the bias magnetization in the MR magnetic sensing part by specifying the substantial arrangement of the electrodes for applying a sense current to the MR magnetic sensing part having the MR effect of the magnetic head and the means for applying a bias magnetic field. To make it possible to set the optimum state in almost the entire range.

[Conventional technology]

A magnetic head that adopts the shield type structure of a conventional MR type magnetic head has first and second magnetic substrates (21) as shown in FIG. and (2
2) A configuration is adopted in which a magnetic head main body consisting of an MR magnetic sensing part (2) etc. having an MR effect is sandwiched between them. (3) is a surface that is in contact with or faces the magnetic medium, which is not shown, but is adapted to move relative to the magnetic head in a direction perpendicular to the plane of the paper in FIG. MR magnetic sensing part (
2) is formed on the substrate α) with its front end facing the surface (3) facing or facing the magnetic medium.

At both front and rear ends of the magnetically sensitive section (2), a sense current Is is supplied to the magnetically sensitive section (2) for detecting a change in resistance based on a signal magnetic field applied to the magnetically sensitive section (2), for example, as a voltage change. A pair of front electrodes (7) and rear electrodes (8) used for
and is provided. These electrodes (7) and (8) are attached so that each end overlaps each front and rear end of the magnetically sensitive part (2), and the front electrode (7) is attached to the magnetically sensitive part (2). It is drawn out from the front end in a direction along the surface (3), that is, in a direction perpendicular to the original direction of conduction of the sense current IS in the magnetically sensitive part (2).

On the other hand, the MR1!5 magnetic part (2) is formed with the required optimum bias magnetization state so that it can receive the signal magnetic field in a state where its magnetoresistive characteristics exhibit the most excellent linearity and high sensitivity characteristics. A bias magnetic field applying means is provided for applying a bias magnetic field for the purpose of applying the bias magnetic field.

As this bias magnetic field applying means, a bias conductor (10) which generates a required bias magnetic field when energized is provided across the magnetic sensing part (2) in order to simplify assembly and manufacturing.

Then, a first magnetic substrate (21) is placed over the magnetically sensitive part (2).
A second magnetic substrate (22) is bonded thereon by a non-magnetic insulating bonding material (13) such as glass, and the first and second
The magnetic substrates (21) and (22) provide a magnetic shielding effect. (11) is an insulating layer interposed between the bias conductor (work 0) and both electrodes (7) and (8) or the magnetic sensing part (2), and for example, the substrate (21
) is deposited on this when it has conductivity.

However, in the MR type magnetic head with such a configuration,
It is difficult to obtain an appropriate bias magnetization state due to the MR magnetic sensing portion (2).

That is, in the magnetic head with this configuration, the magnetization distribution at each position along the original direction of conduction of the sense current Is in the magnetic sensing portion (2), that is, the direction of application of the signal magnetic field, is calculated as follows. The result will be as shown in the figure. In this figure, the curve (9■) is the bias conductor (1
0) shows the distribution of magnetization due to the magnetic field generated when a current of 15 = 2 (lnA) is passed through the electrode (7) without energizing the bias conductor ( 10) shows the distribution of magnetization due to the bias magnetic field generated by flowing Ib=30mA only in the MR magnetic sensing part (2), the bias conductor (10)
In addition to the bias magnetic field from the MR magnetic sensing part (2)
It is also affected by the magnetic field due to the current flowing through the electrode (7) for energizing. Therefore, when 1s=2On+A is set and the bias current 1b to the bias conductor (10) is changed, the magnetization distribution of the MR magnetic sensing part (2) becomes as shown in FIG. 10. In this figure, curves (101) to (
104) sets the current direction to the bias conductor (10) to the seventh
As shown by the arrow in the figure, the magnetically sensitive part (2 ) is the magnetization distribution of the curve (10
5), when Ib=O, the curve (106) shows the current 1
This figure shows a similar magnetization distribution at I b =-30 mA when the direction b of b is opposite to the current direction a in the electrode (7).

In this way, it is difficult to set the optimum bias state over the entire area of the MR magnetic sensing part (2) due to the influence of the magnetic field generated from the front electrode (7), especially in the magnetic sensing part (2). (2) The fact that it is difficult to set an appropriate bias in the front section, which is essentially the sensing section for the signal magnetic field, has a large effect on the characteristics of the magnetic head.

This is due to the fact that in the magnetically sensitive part (2) °ζ, in the part where the electrode (7) is attached, the current is substantially applied to the electrode (7), and the current direction is the same as the current direction to the electrode (7). In other words, the direction is perpendicular to the original current direction in the magnetically sensitive part (2), and is affected by the magnetic field.

[Problem that the invention seeks to solve]

The present invention provides M in an MR type magnetic head as described above.
Aiming to solve the problem of bias magnetic field for the R magnetic sensing part.

Means for Solving Problem f] The present invention, as shown in a plan view in FIG. 1 and in a sectional view in FIG. i! M arranged to flow T s
R1F! ! , a magnetic part (2), and a pair of electric currents Th (71 and (8)) for flowing a sense current Is through this magnetically sensitive part (2). Part (2
) is electrically connected to one end of the part (7A
) and a portion (7B) extending in a direction substantially perpendicular to the original direction of conduction of the sense current Is of the magnetic sensing portion (21) and electrically insulated from the magnetic sensing portion (2).

The magnetically sensitive part (2) is formed on the first magnetic substrate +11 via an insulating rf4 (11), for example. (3) indicates a surface that faces or faces the magnetic medium, and although the magnetic medium is not shown, it moves in a direction perpendicular to the plane of the paper in FIG. 1, facing or facing this surface (3). ing. Then, from the surface (3), so that the signal magnetic field HS due to the recording signal magnetic field on the magnetic medium is applied to the magnetic sensing part (2).
The magnetically sensitive portion (2) is formed so that its front end face faces a surface (3) that faces or faces the magnetic medium, and extends in a direction substantially perpendicular to the surface (3).

On the other hand, the direction of the sense current Is in this magnetically sensitive part (2) is selected to be along the direction of the signal magnetic field, so that the pair of electrodes (7) and (8) for this magnetically sensitive part (2) is selected. ) are arranged at the front and rear ends of the magnetically sensitive part (2), and the electrodes (7) on the front end side (hereinafter referred to as front electrodes) are greatly affected by the signal magnetic field of the magnetically sensitive part (2). )
In, the connection part (7^) to the magnetic sensing part (2) mentioned above
is electrically insulated from the magnetic sensing part (2), and the sense current I
A portion (7B) extending in a direction substantially perpendicular to the direction of s is provided.

Then, the bias conductor (10) for giving the required bias magnetic field to the magnetic sensing part (2) is connected to the sense current I as necessary.
Provided in a direction substantially perpendicular to s. When such a bias conductor (10) is provided, at least the magnetically sensitive part (2)
Insulate the parts that cross the front electrode (7) and the vicinity so that they overlap each other with the same width and the same position as the front electrode (7)! <11).

For example, as shown in FIG. At least one of the soft magnetic thin films (4) and (5) in FIGS. 1 and 2 is made of a soft magnetic thin film having an MR effect, such as Fe+Co, Ni, or an alloy of two or more of these. Moreover, one of these soft magnetic thin films (4) and (5) is Sendust.

It can be constructed from a high magnetic permeability soft magnetic thin film such as a Co-based amorphous alloy or MO permalloy. The non-magnetic thin film (6) interposed between the soft magnetic thin films (4) and (5) is
5i (h, Aj22031 Ti, Mo, Heg, etc.), non-magnetic metal VRT film, etc.Then, this non-magnetic thin film (6) is composed of an inner soft magnetic thin film (4
) and (5), the thickness is selected to be 5 to 10,000 people, or 5 to 500 people in one row, such that magnetostatic interaction acts more dominantly than exchange interaction.

In addition, the inner soft magnetic S crotches (4) and (5) of this magnetic sensing part (2)
1 is selected so that the amount of magnetic flux of both thin legs (4) and (5) matches by selecting the saturation magnetic flux density, thickness, etc., so that the magnetic flux is closed as a whole regarding both 991Q f41 and (5). be done. Then, the inner soft magnetic thin film (4) and (
When 5) is a magnetic thin film having an MR effect, it is desirable that the inner soft magnetic MIIQ (41 and (5) be the same material, size, and shape, but one of them should be made of a material that has no or almost no MR effect. When constructed by, this soft magnetic thin film is
The specific resistance, thickness, etc. of the constituent material are selected so that the electrical resistance is sufficiently larger than that of the other soft magnetic thin film that has the MR effect.

[Effect]

According to the configuration of the present invention, an appropriate bias magnetization state can be obtained in the MR magnetic sensing section (2). That is, in the configuration in which the bias conductor (10) is arranged on the front electrode (7) so as to match the front electrode (7) as shown in FIG. 2, the original sense current Is in the MR magnetic sensing part (2) is The magnetization distribution at each position from the front end in the direction along the energization direction is as shown in FIG. In this figure, the curve (41
) to (43)- are respectively l5-20m8, I b
= 30m^, Ib=OmA.

Each magnetization distribution when Ib=-30mA is shown. According to the graph, a flat magnetization state is obtained in a wide range of the MR magnetic sensing part (2) at a position offset to the front side, and therefore in the substantial sensing part. Therefore, the magnetization state can be reliably set to the open state.

As can be seen from the above, in the present invention, when the signal magnetic field is in the same direction as the sense current Is in the MR magnetic sensing part (2), in other words, the magnetic field sensing part (2)
One electrode (7) is provided at the front end of the , and this is the sense current! This is especially lazy when extending in a direction substantially perpendicular to the direction of S and forcing the feeding end to be drawn out.
As such a magnetic head, as mentioned above, MR
The magnetically sensitive part (2) may have a laminated structure in which soft magnetic thin films (4) and (5) of 21- are connected together via a non-magnetic film (6). Note that when the MR magnetic sensing section (2) has a laminated structure in this way, Barkhausen noise is effectively removed. This will be explained.

First, to explain the cause of Barkhausen noise, when the magnetic sensing part is composed of a single layer of MR magnetomagnetic mirror, as in conventional general MR type magnetic heads,
This MRm thin film has a magnetic domain structure as shown in Figure 11 in order to maintain a state in which the sum of magnetostatic energy caused by magnetic anisotropy energy, shape anisotropy, etc. is minimized as a whole layer. Take. In other words, if this single-layer magnetic thin film is a rectangular magnetic layer IQ (51) and has magnetic anisotropy in the short side direction, within the city, the magnetization direction is alternately opposite along the short side direction. Magnetic domains (52) are generated, and magnetic domains (53) in opposite directions are generated in sequence along the long side direction of the magnetic layer between both ends of the adjacent magnetic domains (52) so as to form a closed loop. Therefore, when an external magnetic field is applied to such a magnetic layer, fIi! Wall (54
), (55) move, which generates Barkhausen noise.

In contrast, in the configuration of the present invention, the magnetically sensitive portion (2)
is a soft magnetic M crotch (41 and () through a non-magnetic thin film (6)
5) has a laminated structure, so that when no external magnetic field is applied, the magnetism @pJ (41 and (5) are indicated by arrows M1 and M2, as shown in Fig. 3).
As shown in , the magnetization states are antiparallel to each other in the direction of the easy axis of magnetization, and no domain wall is generated. In addition, regarding the absence of domain walls in this way, the bitter using magnetic fluid
This was confirmed by magnetic domain observation using the (Bitter) method. And for such a magnetically sensitive part (2),
When the external magnetic field H is strengthened in the direction of the hard magnetization axis, the first
The magnetization state is schematically shown in FIG. 3, shown in FIG. 12A, as shown in FIG. The external magnetic field H causes the magnetization to rotate from the antiparallel magnetization state through the rotational magnetization process as shown in FIG.
) and (5) are magnetized in the same direction. In this case, since the magnetization rotates within the side magnetic thin films (4) and (5), no domain wall is generated, and Barkhausen noise is avoided. In other words, both magnetic thin ff! X! (4
Barkhausen noise caused by domain wall movement can be avoided by setting the direction of the hard magnetization axis of 1 and (5) as the propagation direction of the magnetic flux.

Further, the operation of the magnetic head having such a magnetic sensing portion (2) will be explained with reference to FIGS. 13 to 15. Figure 13~
Figure 15 shows both magnetic thin samples (4) and (5) of the magnetically sensitive part (2).
) is shown schematically, and these magnetic M IIQ
(4) and (5) have an axis of easy magnetization in the initial state in the direction of the edge at ea in FIG. And these magnetic tW
A sense current Is is passed through the crotch f4+ and (5). This energization generates magnetic fields in opposite directions perpendicular to the current Is in both magnetic thin films (4) and (5) facing each other with a non-magnetic thin film (not shown) in between, which causes the magnetic thin film (4)
) and (5) are magnetized as shown by solid line and broken line arrows M1 and M2 in the figure. On the other hand, when a bias magnetic field HFI is externally applied to the +iI part (2) in the direction along the current Is, the direction of magnetization of the magnetic thin films (4) and (5) is changed by this bias magnetic field H. Arrow M in Figure 14
It is rotated by the required angle as shown by B1 and MB2. The direction of magnetization given by this bias magnetic field Ha is approximately 45° with respect to the direction of the current Is,
The magnitude of the bias magnetic field H, is selected.

In this way, the bias magnetic field HB causes the sense current I
The fact that it is possible to obtain jealousy sensitivity and linearity by applying magnetization at an angle of approximately 45° with respect to s is the same as in ordinary MR type magnetic heads.

In this state, as shown in FIG. 15, the signal magnetic field H
5 is applied in the direction along the sense current Is, that is, in the direction of the hard magnetization axis, the magnetization rotates, and the direction of the magnetization rotates counterclockwise and in the hour hand direction by angles θ1 and -01, respectively, as shown by arrows MS and MS2. .

As a result, if the magnetic thin films (4) and (5) are both MR magnetic thin films, a change in resistance will occur, but the change in resistance of this MR magnetic thin film is calculated when the change in angle is θ. Since it is proportional to cos2 θ, if the magnetizations MB1 and MB2 of the inner magnetic thin films (4) and (5) in FIG. 14 are shifted by 90 degrees from each other, then
By changing θ1 and -θ1, the internal magnetic thin films (4) and (5)
The increase or decrease in resistance changes with respect to In other words, if the resistance of one magnetic thin film (4) increases, the resistance of the other magnetic thin film (4) increases.
5) The resistance also changes in the direction of increasing.

Then, the resistance change of these magnetic FX IIQ (4) and (5), that is, the resistance change occurs between the terminals t1 and 2 at both ends of the magnetic sensing part (2), and this resistance change is caused by the voltage between the terminals t1 and +2. This means that it can be detected as a change.

As described above, the MR magnetic sensing part (2) has a structure in which the first and second soft magnetic thin films (4) and (5) are laminated with the nonmagnetic thin film (6) in between. (Barkhausen noise is improved, but in this case, from the above, it is understood that the sense current I to the magnetically sensitive part (2)
The direction of s is selected to be the same direction as the direction in which the signal magnetic field HS is applied.

〔Example〕

An example of the present invention will be described in detail with reference to FIGS. 1 and 2.

In this case, for example, Ni-Zn ferrite, Mn-Zn
For example, an insulating layer (11) of 5i02 or the like having a thickness of 0.8 μm is formed on a first magnetic substrate (Ll) made of a magnetic ferrite or the like, and a first soft magnetic thin film (4) and a non-magnetic thin film (4) are formed on this. A magnetic thin film (6) and a second soft magnetic thin film (5) are sequentially formed by sputtering or an evaporation device, and patterned by photolithography to form an MR magnetically sensitive part (2).

The non-magnetic thin film (6) is made of an insulating or conductive non-magnetic material such as 5T02, Ti, etc., and its thickness is such that there is no substantial exchange interaction between the inner magnetic thin films (4) and (5). The thickness is selected to be, for example, 20, so that there is almost no effect and coupling by interaction according to Coulomb's law, that is, magnetostatic coupling occurs.

One of the two magnetic thin layers (4) and (5) may be composed of Fe, Ni, Co, or an alloy of two or more of these, as described above.

At the front and rear ends of the MR magnetic sensing part (2),
An electrode (7) and (
8) is electrically deposited. Ll and +2 indicate the terminals of these electrodes (7) and (8).

The front electrode (7) has a portion (7A) that is electrically connected and attached on the front end of the magnetically sensitive part (2), and a part (7A) that is electrically connected to the front end of the magnetically sensitive part (2) and the original direction of the sense current Is in the magnetically sensitive part (2). It has a portion (7B) that extends in a perpendicular direction and is electrically insulated from the magnetically sensitive portion (2) via an insulating layer (11).

The width W of the electrode (7) is selected to be 7 μm, for example, and the portion (7)
8) The adhesion width W1 to the magnetically sensitive portion (2) is selected to be, for example, 2 μm.

Then, a bias conductor (10) is placed on the electrode (7) via an insulating layer (11) with a width W and a position that match the electrode (7), at least in the overlapped portion with the magnetically sensitive part (2).
). That is, this bias conductor (10) is
Sense to the magnetic sensing part (2)'! ! It extends in a direction perpendicular to the sense current Is, and is energized in this direction to apply a bias magnetic field H8 in the direction along the sense current Is to the magnetic sensing part (2). conductor(
10) shows the current-carrying terminal.

Then, a non-magnetic adhesive material (13) such as glass is placed on the substrate (envelope) so as to cover the magnetic head components such as the magnetic sensing part (2).
For example, the second magnetic substrate (22) is bonded to the first magnetic group N1 (21) at a distance of 0.8 μm through the substrate.

In the above structure, each layer, such as the insulating layer (11), the bias conductor (10), the electrodes (7) and (8), etc., is formed by sputtering or vapor deposition, and is formed into a desired pattern by photolithography. obtain.

In the above configuration, the magnetically sensitive Ql (2+ is in a state where a DC sense current Is is applied between its electrode conductive layers (7) and +8), and a required current is applied to the bias conductor (10). is applied so that the required bias magnetic field HB is applied. In this state, by moving the magnetic recording medium in a direction perpendicular to the paper plane in FIG. 1 while facing or facing the magnetic recording medium, the recorded magnetization on this medium is A signal magnetic field HS corresponding to the magnetic field Hs is applied to the MR magnetic sensing part (2) in the same direction as the sense current IS, and a resistance change corresponding to the change in the magnetic field Hs occurs in the magnetic sensing part (2). Reading of the recording on the recording medium will be performed.

In addition, the magnetic layer M'A (41 or (5) of either one of the bivalent thin films (4) and (5) of the MR magnetic sensing part (2) is
Even in the case of using a magnetic thin film that has almost no MR effect, the thickness etc. are selected so that the magnetic flux amounts of both magnetic layers (4) and (5) match as described above, and the one that has almost no MR effect is selected. Regarding the magnetic thin film, the electrodes (7) and (8) at both ends of the non-MR magnetic thin film are connected so that the main part of the sense current flows through the magnetic thin film having the MR effect.
The resistance between FeCo51B series and CoZrNb, which have high specific resistance, is sufficiently larger than that of the MRfa thin film.
It can be constructed by a high resistivity, high permeability magnetic layer, such as amorphous alloys of the system or so-called sendust alloys of Fe-^1-3t threads. Mo permalloy or the like may be considered as a material that can be used for this high permeability magnetic layer with a small MR9J1 effect. Of course, these materials are used for electrodes (7) and (8).
It can also be considered as the first material.

In the above example, the bias conductor (10) is provided to apply the external magnetic field HB to the magnetically sensitive part (2), but if the bias conductor (10) is superimposed on the electrode (7), If the bias conductor (10) is provided as shown in FIG. 5 and its cross-sectional view is shown in FIG. is provided across the magnetic sensing part (2), and a bias current 1b is supplied from a constant current source SR between both ends of the electrode (7).
It is also possible to superimpose and supply the sense current ■S from the constant current source SS between (8) and (8).

〔Effect of the invention〕

As described above, according to the present invention, since the unstable mutual influence between the magnetic field by the front electrode (7) and the bias magnetic field on the MR magnetic sensing part (2) is avoided, stable and appropriate bias magnetization can be achieved. state can be obtained in the MR magnetic sensing part (2),
This makes it possible to reliably obtain a magnetic head with high sensitivity and excellent linearity.

[Brief explanation of the drawing]

FIG. 1 is an enlarged plan view of an example of the magnetoresistive magnetic head according to the present invention, FIG. 2 is a cross-sectional view taken along the line A-A, FIG. 3 is an explanatory diagram of the magnetic sensing part, and FIG. 4 5 is an enlarged plan view of another example of the magnetoresistive magnetic head according to the present invention, and FIG. 6 is its A-
7 is a cross-sectional view along line A, FIG. 7 is an enlarged plan view of a conventional magnetoresistive magnetic head, FIG. 8 is a sectional view taken along line A-A in FIG. 7, and FIGS. 9 and 10 are respectively A diagram of the magnetization distribution curve of the magnetic sensitive part, Fig. 11 is a diagram showing the ffi layer extramagnetic thin film structure, Fig. 12 A-C is an explanatory diagram of the magnetization state of the magnetic sensitive part due to an external magnetic field, and Fig. 13 ~FIG. 15 is an explanatory diagram of the operation of the magnetic head. (21) and (22) first and second magnetic substrates, (2)
(4) and (5) are the first and second soft magnetic thin films, (6) is the non-magnetic thin film, (71 (81 is the electrode, (
10) is a bias conductor.

Claims (1)

[Scope of Claims] A magnetoresistive magnetic sensing part arranged to flow a sense current in the same direction as the direction of a signal magnetic field, and a pair of electrodes that flow a sense current in the magnetic sensing part, One side extends in a direction substantially perpendicular to the direction of the sense current of the magnetically sensitive section and a portion connected to one end of the magnetically sensitive section, and is electrically insulated from the magnetically sensitive section. 1. A magnetoresistive magnetic head, comprising a portion extending upwardly.