JPS59162615A - Magneto-resistance effect head - Google Patents

Abstract

PURPOSE:To extend a region accompanied with magnetizing rotation without requiring the working of minute grooves by providing parallel and linear projecting parts or recessed parts on the surface of a substrate constituting a ferromagnetic magneto- resistance effect element (MR element) or the surface of an antiferromagnetic material which is brought into contact with the MR element. CONSTITUTION:Grooves 3 are formed in parallel on the surface of a substrate 2, and an MR element 1' is formed on the substrate 2. An antiferromagnetic material 4 which performs of direct exchanging action with the MR device is laminated on the element 1'. Consequently, if an axis E.A of easy magnetization of the element 1' is set to the direction of grooves 3, the direction of magnetization of an atom layer, which forms an interface with the MR device, of the antiferromagnetic material 4 is set to the direction of grooves 3. An angle made by the direction of a length l of the element 1' and the direction of grooves 3 is set to a prescribed value theta. Consequently, a sense current I forms the angle theta with grooves 3. Because of the existence of grooves 3, the element 1' is magnetically divided to stripe-shaped MR devices 6 and 7. Consequently, when an external signal magnetic field is applied to the element 1', magnetization M of devices 6 and 7 is rotated smoothly from the start point theta in accordance with the intensity of the external signal magnetic field, and the action of the unstable magnetization M is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention includes a ferromagnetic magnetoresistive element (hereinafter referred to as an MR element) that reads magnetic information written on a magnetic storage medium using a so-called magnetoresistive effect. The present invention relates to a magnetoresistive head (hereinafter referred to as an MR head).

MR heads are attracting attention as a device that greatly contributes to improving recording density in magnetic recording.

However, as is well known, when an MR ice is used as a highly efficient reproducing head that exhibits a linear response to magnetic information written on a magnetic storage medium, the MR cumulative If the angle formed by the sense current (2) flowing through the element 1 and the magnetization M of the MR element is (rho), the above-mentioned - is set to approximately 45' (earth means must be provided).

Conventionally, a specific method for providing the bias means described above includes MR.
Place it close to (or in contact with) the element and magnetically
A strong magnetic material or a good electrical conductor is placed, and the magnetic field generated by the current flowing through the magnetic material or the good electrical conductor is used as a bias magnetic field, and the angle 6 of the MR hydrogen magnetization M is the sense current angle of approximately 4.5°. There are known ways to set it. However, these biasing methods require relatively large magnetic fields, which can alter the information on the magnetic storage medium. In particular, the former magnetically hard magnetic material is M
When the R hydrogen atoms are closely opposed (or in contact), the angle is 6.
It is difficult to set the angle exactly at 45 degrees, and if the latter electrically conductive material is placed close to (or in contact with) MR hydrogen atoms, it is necessary to flow a relatively large current through the electrically good conductor. , the electrical resistance of the M element causes thermal drift,
It also caused thermal noise.

In addition, as another known example, in contrast to the bias method using an external magnetic field described above, as shown in FIG. There is a method of setting the EA to approximately 45 degrees. This method has advantages such as the ability to externally attach an MR hydrogen element for applying a bias magnetic field. In order to specifically realize this method, it is necessary to reduce the induced magnetic anisotropy that occurs during deposition in a magnetic field and the magnetic anisotropy that occurs during oblique evaporation to ′fF.
ll, the easy axis of magnetization E-A is the longitudinal direction of the MR hydrogen element,
[RI] A method is adopted in which the sense current is set at approximately 45 degrees with respect to the direction in which the current flows.

However, for example, 80 qbN 120% F
No-Malloy with a composition around e (weight percentage) is processed into a pattern with a film thickness tM of about 200 to 600 mm and a length of several tens to 100 μm and a width W of several μm to 10 μm. Demagnetizing field 1 due to the shape (d4πM5tM/W is about several tens of Rusteds. However, here, Hd is the demagnetizing field in the film width direction, and M is the saturation magnetization of 8O-N1-20%Fe. It has a value of about 800 e-mu.

In this case, the anisotropic magnetic field Hk obtained by deposition in a magnetic field
is of the order of a few Oersteds, so Hk<<H
d, the magnetization direction of the MR element was substantially parallel to the sense current, contrary to its intended purpose, and its effect as a biasing means was not recognized.

In addition, the anisotropic magnetic field obtained by the oblique evaporation method has a value of several lO Oersted, and in some cases the MR hydrogen easy magnetization axis can be set at approximately 45 degrees with respect to the direction of the sense current I, but the anisotropic magnetic field and It was difficult to control the direction of easy magnetization, making it impossible to bias with good reproducibility, and variations in characteristics were likely to occur between M-type devices fabricated at the same time, which was disadvantageous in terms of productivity.

- 10,000, this book describes another method of setting the MR hydrogen easy magnetization axis g-A at approximately 45 degrees from the beginning with respect to the sense current flowing in the longitudinal direction of the Δ(R element), which solves the above-mentioned bias defect. The applicant's "Jog MR element" was granted a patent application in 1973.
No. 7-050586. The jog MR element has an MR hydrogen element provided on a substrate having one or more mutually parallel linear convex parts or four parts, and utilizes the shape demagnetizing field generated by the convex parts or concave parts to produce MR confectionery. This is to control the angle θ formed between the magnetization M and the sense current.

When the pitch between the nine adjacent convex portions or concave portions of the MR hydrogen element in such a configuration is extremely small, for example, when grooves with a pitch of 1 μm or less are formed, the angle formed by the magnetization M and the sense electric current is set to approximately 45 degrees. can. However, processing the above-mentioned convex or concave portions with extremely small pitches requires special techniques and equipment such as laser holography, Fi electron beam exposure, etc., and requires a large number of man-hours, resulting in a decrease in yield. However, the MR head has drawbacks such as a long manufacturing time, and as a result, the MR head has to be expensive.

Furthermore, if the above-mentioned pitch is set to the order of several μm, which is achievable with ordinary nail graphography technology, the angle formed by the magnetization M and the sense current I can be controlled to some extent, but it is not sufficient.
Since the region of linear response to an external signal magnetic field is narrow, and noise such as noise is generated, this tends to bring about extremely unfavorable results in the magnetic conversion characteristics of the MR head. An object of the invention is to provide a magnetoresistive head that solves the above-mentioned conventional drawbacks.

According to the present invention, in a magnetoresistive head in which a ferromagnetic magnetoresistive element is laminated with an antiferromagnetic material capable of performing magnetic exchange coupling, a substrate forming the ferromagnetic magnetoresistive element is A magnetoresistive head characterized in that a surface of the antiferromagnetic material that comes into contact with the ferromagnetic magnetoresistive element has one or more mutually parallel linear convex portions or concave portions. can be provided.

That is, the present invention utilizes the shape demagnetizing field of the MR element generated by the convex or concave portions provided on the substrate, and sets the angle formed by the magnetization M of the MR element and the sense 'tIL flow to a predetermined value θ. In addition, the change due to the external signal magnetic field of .beta. is smoothly performed by utilizing the magnetic exchange interaction that occurs between the antiferromagnetic material and the MR element.

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 3 shows the main components of the MR head of the present invention.
This is an example showing a VIFL element portion.

Other components, such as magnetic shields, have been omitted to simplify the explanation.

The surface of the insulating substrate material 20 made of glass, fezite, ceramics, etc. has a width l formed by a method such as photoresist and etching solution or ion milling, and is 7-bit J41.
A large number of linear grooves 3 are formed so as to be substantially parallel to each other. Then, to cover this groove 3, an MR element made of a ferromagnetic material (for example, Fe-Ni alloy, N
i-Co alloy, etc.) 1' is p
It is shaped like a sphere. Furthermore, f'iMR is placed on the MR element 1.
An antiferromagnetic material 4 that has direct exchange interaction with the element is laminated by sputtering, vapor deposition, or the like. As is well known, the direct exchange interaction 2 referred to here means that at the interface between the antiferromagnetic material 4 and the MR element, the direction of magnetization of the atomic layer of the antiferromagnetic material 4 and the direction of magnetization of the MR crystal 1 are in the same direction. This is an effect that is consistent with . Therefore, if the axis of easy magnetization E-A of the MR element 1' is set as shown in the same figure, if the internal pressure of the linear blade of the groove 3 is set, the atomic layer of the antiferromagnetic material 4 formed thereon which forms the interface with the MR element. The direction of magnetization is set in the full 3 linear direction. The MR element 1'
Then, the MR element 1' and the antiferromagnetic material 4 are processed to have a length L1 and a width W using four antiferromagnetic materials, a photoresist, an etching solution, or ion milling. At this time, M
The angle formed between the longitudinal direction of the R element 1' and the antiferromagnetic material 4 and the linear direction of the groove 3 is set to a predetermined value θ. Furthermore, both longitudinal ends of the M element 1 and the antiferromagnetic material 4 are connected to two electrical terminals 5 for introducing a sense current into the M1'L element 1'.
is connected. Therefore, the sense current I introduced from the electric terminal 5 forms an angle θ with the linear direction of the groove 3.

Due to the presence of the plurality of grooves 3 mentioned above, the MR element 1' is magnetically divided into strip-shaped MR elements 6 and 7 having a plurality of widths l and E. As a result, the length of the truncated MR elements 6 and 7 in the longitudinal direction is 9nθ. At this time, the said patent application No. 57-050
586K As disclosed, when there is no antiferromagnetic material 4, that is, when the MR element 1' is present alone, the strip-shaped MR element 6
If length W of It is easy to face and stable, and the groove 3
does not contribute to the electrical division of the MR element 1'; therefore, the direction of the sense current (2) is continuous even in the strip-shaped MR elements 6 and 7. The magnetization M of the strip-shaped MR elements 6 and 7 and the sense current of the MR element 1' form a certain value θ (preferably 45 degrees) determined by the groove 3. However, in reality ->>I<or/')
In order to satisfy the θ condition, for example, when W=XO μm θ−45° (ie, W = 14 μm), 19nθ (or J′) is suitably 1 μm or less. As mentioned above, forming the groove 3 having such a small width on the substrate 2 requires special techniques and equipment such as laser holography <electron beam exposure. Also, J.

For example, if and l (or !') are of equal size,
In the above numerical example, when lt (or l') is several μm, the groove 3 can be formed using ordinary photolithography technology, but the demagnetizing field in the length direction of the strip-shaped MW element 6 or 7 is The influence becomes large, and the angle between the magnetization M and the sense current cannot be set to θ, and the magnetization M exhibits unstable behavior with respect to the external signal magnetic field. This results in the disadvantage of Barkhausen noise.

However, as shown in FIG. 3, when the antiferromagnetic material 4- which has direct exchange interaction with the MR element 1' is laminated, a and l (or l) are of equal size and the real , the magnetization M of the MR element 1 including the strip-shaped MR elements 6 and 7 is the antiferromagnetic material 4.
Since the magnetization direction of the atomic layer in contact with the MR element 1 corresponds to the direction of magnetization, if the magnetization of the antiferromagnetic material 4 is set to be approximately parallel to the linear direction of the groove 3, the magnetization of the strip-shaped MFL elements 6 and 7 will be M can be set substantially parallel to the linear direction of the groove 3.

Therefore, when an external signal magnetic field is applied to the MR element 1 of the present invention, the magnetization of the antiferromagnetic material 4 always rotates smoothly in accordance with the groove 3, resulting in sudden magnetization reversal, domain wall movement, etc. The unstable behavior of magnetization M (ie Barkhausen noise) is suppressed. In this way, there is no need for minute groove machining, which is a drawback of the prior art, and moreover, the region with magnetization rotation, that is, the region where the resistance changes linearly with respect to the external signal magnetic field, l:<1. ? , Barkhausen noise also disappears.

Furthermore, in the present invention, since the MR element 1' is magnetically divided into a large number of strip-shaped MR elements 6 and 7, the MR element 1'
Since the demagnetizing field at both ends in the width direction of the MR element 10 is extremely small compared to the case where the groove 3 does not exist, the uniform bias magnetic field of the antiferromagnetic material 4 increases the magnetization M and the sense current over the entire region in the width direction of the MR element 10. I can be set to a predetermined angle. Therefore, compared to the case where the groove 3 does not exist, the detection sensitivity near both ends of the MR element 1' in the width direction is greatly improved.

As described above, in the MR element of the present invention, the MR element formed on the top is divided into many strips by the many linear grooves formed in the substrate material, and the width of the MR element is divided into many strips. The demagnetizing field in the direction is substantially reduced, and the magnetization M of the MR element is easily oriented in the direction of the linear groove. Therefore, due to the bias magnetic field formed on the MR element through the direct exchange interaction by the nine antiferromagnets, the magnetization on the M sense current over almost the entire width direction of the MR element and the arbitrary It can be set at an angle (preferably 45 degrees). Moreover, the pitch of the many linear grooves can be processed on the order of several μm using ordinary photolithography, which eliminates the technical difficulties associated with conventional groove processing and the need for bulky equipment. can.

. Further, in the present invention, it is preferable to use a magical conductor as the antiferromagnetic material. The conductive antiferromagnetic material is, for example, Mh-F
, alloys are preferred. Al6-J'3 alloy and MR element,
In particular, regarding the direct exchange interaction of Ni-Fe alloy Δ4R elements, IEgET Transactionon
Magnetics 1978, Volume 14, 521-
RID, H'amp s t described on page 523
Paper by e a d et al.” Unidirecti
onal Ar+1sotropy in N1cke
l -Iron Films I)31 Exchange
ge Coupling with, Ant eye erro
Magnetic Fi1ms'' has been reported.

In this paper, Mn50%-Fe5 is used as the antiferromagnetic material.
A bias magnetic field of approximately 30 oersted is achieved using a 0% alloy (all weight percent).

By stacking such a conductive antiferromagnetic material with an MFL element, the sense current supplied to the MR element is also shunted to the antiferromagnetic material, and the magnetic field due to the current shunted to the antiferromagnetic material is utilized. In this way, the angle formed by the sense current and the intensification N1 of the R element can be finely adjusted.Moreover, in this case, unlike the prior art described above, a large current is not required, and therefore the cleanliness on the magnetic storage medium can be adjusted. There is no risk of destroying the information (there is no risk of thermal drift of the electrical resistance of the MEL element, or generation of thermal noise.In addition, the magnitude of the current shunted to the antiferromagnetic material, id, and the magnitude of the sense current are changed. Alternatively, you can change the thickness of the antiferromagnetic material.

Furthermore, another advantage of using a monolithic conductor for an antiferromagnetic material is that
The MIt element F formed on the groove becomes more likely to be electrically disconnected as the depth of the groove increases, resulting in unstable conduction, but due to the presence of the conductive antiferromagnetic material, , the conductive region (l-1II'G) M R, the thickness of the element,
The total thickness of the antiferromagnetic material) increases, and the MR
The element as a whole should be electrically stable. That is, if the total thickness of the MFL element and the antiferromagnetic material is thicker than the groove 4-J, the MFL element will not be cut by the sense current.

As described above, the present invention has been described by forming grooves on the surface of the continuous substrate 4A1'.
Although the embodiment has been described in which MI (layer 7) and antiferromagnetic material are formed thereon, another V embodiment is illustrated in FIG.

Figure 4 shows an antiferromagnetic material 4 directly applied to a substrate 2 with a smooth surface.
The anti-hard shell 4 is made of photoresist and an etching solution or ion milling method, etc., and a large number of linear grooves 3 each having a width of 11 and a pitch of /+/ are approximately Y - It has a structure in which the grooves 3 are formed in rows, and then NiR resistors 1 are formed by a method such as sputtering or vapor deposition so as to cover the grooves 3. By adopting such a configuration, if the antiferromagnetic material 4 is an electrical insulator, the substrate material 4 does not need to be insulating and may be a conductive material such as Si.
It has the feature that wafers and the like can also be used, increasing the range of choices for the substrate material 4.

As described above, according to the present invention, it is possible to provide an MR head that achieves a good bias state.

[Brief explanation of the drawing]

Figures 1 and 2 are schematic diagrams showing the configuration of a conventional NR Kiko, Figure 3 is a schematic perspective view of an embodiment of the present invention, and Figure 4 is a schematic perspective view of another embodiment of the present invention. It is a diagram. In the figure, 1 and 1' are M tag elements, 2 is a substrate material, 3 is a groove, and 4 is an anti-strong fM material.

Claims (4)

[Claims] (1) In a magnetoresistive head in which a ferromagnetic magnetoresistive element is laminated with an antiferromagnetic material capable of performing magnetic exchange coupling, the surface of the substrate forming the ferromagnetic magnetoresistive element, or A magnetoresistive head characterized in that a surface of the antiferromagnetic material that comes into contact with the ferromagnetic magnetoresistive element has one or more mutually parallel linear convex portions or concave portions. (2) The magnetoresistive head according to claim 1, wherein the antiferromagnetic material is a good electrical conductor. (3) The magnetoresistive head according to claim 1 or 2, wherein the antiferromagnetic material is an M4 Fe alloy. (4) The magnetoresistive head according to item 1 of the patent, wherein the axis of easy magnetization of the ferromagnetic magnetoresistive element is substantially parallel to the linear groove.