JPS58166527A - Magnetoresistance effect head - Google Patents

Abstract

PURPOSE:To improve reproducibility, by providing a ferromagnetoresistance effect element on an insulating substrate having grooves and specifying the angle between the grooves and a current which flows through the ferromagnetoresistance effect element. CONSTITUTION:In the insulating substrate material 4, the grooves 5 are formed in parallel. Because of numbers of the grooves 5, numbers of slanting surfaces 6 and flat surface 7 are formed inevitably at the same time. The magnetoresistance effect element 8 made of a ferromagnetic material in a thin film shape which has length L and width W is formed by covering the grooves 5, slanting surfaces 6, and flat surfaces 7. In this case, the lengthwise direction of the element 8 and that of the grooves 5 contain an angle theta of 30-60 deg..

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. Magnetoresistive head (hereinafter referred to as "magnetoresistive head")

(referred to as 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 using an MR element as a highly efficient reproducing head, some kind of bias means is required. As shown in FIG. 1(a), the electrical resistance R of the MR element 1
Let θ be the angle between the current flowing through it (sense current) ■ and the magnetization M of the MR element itself, then R=R0−ΔRo tdn” e ”’
"' (1) Here, Ro is the electric resistance of the MR element l when the angle θ between the sense current I and the magnetization M is zero, and Ro-ΔR0 is the electric resistance when θ is 90 degrees. Furthermore, if the easy axes of magnetization E and A of the MR element 1 are parallel to the sense current I as shown in the figure, then according to the formula (1), the 9 degrees of the external magnetic field He will be in the direction orthogonal to the easy axis of magnetization EA. When the resistance changes A of the MR element 1 as shown in FIG. In order to increase the output and output, it is necessary to set the angle θ between the sense current I and the magnetization M to approximately 45 degrees in advance. Various bias methods have been proposed for setting the MR element 1. Fig. 2 shows the so-called conductor bias method, in which an electrically good conductor (bias conductor) is placed close to or in contact with the MR element 1. 2
The bias magnetic field Hb is a magnetic field perpendicular to the easy magnetization axes E and A generated by passing a current through the bias conductor 2, and the bias magnetic field Hb causes the magnetization M to flow in the longitudinal direction of the MR element l. This method sets the angle at 45 degrees with respect to the direction of .

However, this method requires a relatively large current to flow through the bias conductor 2, and therefore the electrical resistance of the MR element 1 causes thermal drift and also causes thermal noise. Furthermore, adjustment of the current value of the bias conductor 2 is complicated because it is necessary to strictly set the angle e formed by the sense current l and the magnetization M to 45 degrees. Also, bias conductor 2
Instead, a method known as the hard film bias method in which a magnetically hard magnetic material is placed in close opposition to (or in contact with) the MR element 1 to obtain the bias magnetic field Hb is also known, but this method is also similar to the above-mentioned conductor. As with bias, it is difficult to set the angle 0 exactly to 45 degrees. Furthermore, the above 2
In the two known examples, the bias magnetic field Hb has a relatively large value, so there is a fear that the information on the magnetic storage medium may be changed by the bias magnetic field Hb. As a first method, there is a method in which the axis of easy magnetization of the MR element is set at 45 degrees from the beginning with respect to the sense current I flowing in the longitudinal direction of the MR element. However, with this method, it is difficult to make the direction of magnetization M exactly coincide with the axis of easy magnetization due to the shape anisotropy of the MR element itself, and there is no reproducibility.

In contrast to the method shown in the first two known examples in which the magnetization M of the MR element is deflected by 45 degrees 'WPr with respect to the sense current I, FIGS. This is a known example in which the magnetization M is deflected at approximately 45 degrees. Figure 3 is MR
This is a method in which a large number of slits are formed in the element 1 at an angle of approximately 45 degrees with respect to the axis of easy magnetization E and A to change the current path. However, in this method, due to the shape anisotropy of the MR element l described above, the magnetization M′Fi, the easy axis
．． The magnetization M is not parallel to the sense current I, but is mostly parallel to the sense current I, and as a result, it is difficult to maintain the magnetization M and the sense current I at approximately 45 degrees. The Barber Pole type MR element shown in FIG. 4 is attracting attention as a solution to the problems of the conventional bias method described above! The Barbani ball type MR element is as shown in the figure.
A large number of strip-shaped electrically conductive conductors 3 are brought into contact with the MR element 1 at an angle of about 45 degrees with respect to the easy magnetization axes E and A of the MR element 1, and the sense current I passing through the MR element l is abbreviated as magnetization M. 4
It is set to 5 degrees. However, in such a structure, due to the presence of many strip-shaped electrically conductive conductors 3, M
This inevitably leads to a decrease in the overall external electrical resistance of the R element 1, and further reduces the effective detection area of the signal magnetic field, resulting in a decrease in output.

An object of the present invention is to provide a magnetoresistive head that solves the above-mentioned conventional drawbacks.

The present invention provides an MR element on an insulating substrate material provided with one or more linear unevenness parallel to each other, and
It is characterized in that the current flowing through the element forms an angle in the range of 30 degrees to 60 degrees with respect to the boundary line of the corrugated portion.

That is, the principle of the present invention is to utilize the shape anisotropy of the MR element to determine the angle formed by the magnetization M and the current l by the concavo-convex pattern.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 5 shows the MR head which is the main component of the MR head of the present invention.
This is an example of the R child part. Other components, such as magnetic shields, are omitted to simplify the explanation.

As shown in FIG. 5(a), a large number of linear grooves 5 are formed in the insulating substrate material 4 so that they are substantially parallel to each other. By forming a blind number of grooves 5 on the substrate material 4, a large number of slopes 6 and flat surfaces 7 are inevitably formed at the same time. MR element (e.g., l·-Ni alloy, Ni-0
(alloy, etc.) 8 is formed in a thin film shape with a length and width W of 1. Both ends of the MR element 8 in the longitudinal direction are good electrical conductors (
For example, it is connected to two electrical terminals 9 made of Au, Ou, Ag, etc.). In this case, the effective length of the signal magnetic field detection portion of the MR element is L/. The longitudinal direction of the MRR element 8 and the longitudinal direction of the groove 5 are formed so as to form an angle θ having a value ranging from a minimum of 30 degrees to a maximum of 60 degrees (preferably 45 degrees). Therefore, the MR element 8 is connected via the electrical terminal 9.
The current I flowing therein forms an angle θ with respect to the longitudinal direction of the groove 5 ranging from a minimum of 30 degrees to a maximum of 60 degrees.

Many of the above mentioned $5. Slope 6. Due to the existence of the flat surface 7, M
The RR element 8 is connected to the M on the groove 5 as shown in the plan view of FIG.
R Dakamiko 10 MRR child 11° on slope 6 M on flat surface 7
It is magnetically divided from the RR element 12. As a result, the length of the jiMR elements 10, 11 and 12 in the longitudinal direction is "
This is a value that is sufficiently large compared to the length of each MR element in the width direction. Therefore, the easy magnetization axes 1. of MRR elements 10.11 and 12. The direction of A, that is, the direction of magnetization M, is approximately parallel to the longitudinal direction of MRR elements 10, 11 and 12, that is, the direction of groove 5, due to the shape anisotropy of each MR element. On the other hand, the existence of 1 port 5 is MR.
It does not contribute to the electrical division of the R element 8, and therefore the direction of the sense current I is continuous in the MR* elements 10, 11 and 12. In other words, the magnetization M of each λfR element and the sense current of the MR element ■ will make the aforementioned angle θ ranging from a minimum of 30 degrees to a maximum of 60 degrees determined by #$5.

Hereinafter, the MR resistor that sets the angle between the magnetization M of the MR element and the sense current I using the structure of the present invention described above, that is, the solution formed on the substrate will be described below.
It will be referred to as "MR element".

A minute signal magnetic field Hs is applied to the Jonog MR element of the present invention from the outside.
When is applied so as to be perpendicular to the sense current, the angle formed by the magnetization M of the MR element and the sense current ■ changes around the angle 0, as shown in Figure 1(b). A resistance change C of the MR element similar to that obtained when the bias magnetic field Hb is applied is obtained.

The continuous shape of the Jonog MR element is not limited to the trapezoidal shape as shown in FIG. 5, but is shown in FIGS. 6(a) and (b).

The shape shown in (C) may also be used. However, in the embodiment shown in FIG. 6 as well, it goes without saying that the angle 0 between the wire 5 and the direction of the current flowing through the MR element is selected to be a value in the range of 30 degrees at the minimum and 6.0 degrees at the maximum. 6(a), the MR element P is formed only on the slope 6 and the flat surface 7, FIG. 6(b) shows the MR element P formed only on the slope 6, and FIG. It has a groove shape.

Furthermore, when changing the length L', film thickness, and radius W of the jog MR element, the number of magnetic divisions of the MR element can be changed to an appropriate value, and this can be done by changing the groove shape and groove depth. , and Mato no Ma 1
4% or more can be easily achieved by changing the fineness of the groove, and can be set so that it is always substantially parallel to the groove in the direction of magnetization MO force. In addition, MR elements are formed by methods such as vapor deposition, sputtering, and plating, but at that time, if an external magnetic field is applied parallel to the groove direction of the substrate material, the direction of the easy axis of magnetization, that is, the direction of magnetization M, can be more accurately aligned with the grooves. The directions can be matched.

Note that depending on the direction of the magnetization M of the jog MR element of the present invention, the magnetization M in adjacent strip-shaped MR elements may be different from each other depending on the groove shape, the depth of #I, the interval between grooves, and the number of grooves. There are cases where it is more stable to be antiparallel. In this case, it is clear that the electrical resistance of the Jiggly MR element does not change at all due to the minute signal magnetic field Htn. To avoid such a situation, it is desirable to use some kind of bias means to align the magnetization M of each MR element of the jog MR element in the same direction. For example, as shown in FIG. 7, an electric conductor (bias conductor) 2 is arranged close to (or in contact with) the jog MR element 8, and the bias conductor 2 is connected to the jog MR element 8. The direction of the magnetization M of the MR element may be aligned using the magnetic field HB generated by flowing the bias current IB in parallel with the sense current I. Alternatively, instead of the electrically good conductor 2, a magnetically hard magnetic material is placed in close opposition (or contact), and the direction of the magnetization M of the MR element is aligned by the leakage magnetic field from the magnetically hard magnetic material. Also good. These methods are the same as the conventional techniques described above, namely the conductor bias method and the hard expansion bias method, but in the dimagnetic MR element, the easy axis direction of magnetization is uniquely determined by the groove formed in the substrate. In addition, the magnetization M is parallel to the easy magnetization axes E and A, and the reversal of the direction of the magnetization M is performed using a magnetic field approximately equal to the coercive force of each MR element. M.R.
Adjustment of the angle 0 between the sense current I and magnetization M of the element and a large bias magnetic field Hb are not required.

The MR element, which is the main component of the MR head of the present invention, has been explained above, but in general, an MR head is not composed of a single MR element, but requires a magnetic shield to improve resolution and improve high frequency characteristics. It is. FIG. 8 shows an embodiment in which the jog MR element of the present invention is applied to a magnetically shielded MR head. In FIG. 8, a first magnetic shield 1 made of a high magnetic permeability magnetic material such as permalloy is placed on an insulating base 13 to serve as a slider of an MR head.
4 is formed, on which a jog MR element of the present invention (as described above, an MR element 8 on a substrate material 4 having uneven grooves is formed) is formed, and electrical terminals 9 are connected from both ends of the jog MR element. This figure shows the configuration of an MR head in which a second magnetic shield 16 is formed with an insulating layer 15 interposed between the jog MR element and the first magnetic shield 14. As is well known, in this configuration, the minute signal magnetic field Hs from the magnetic storage medium reaches only the gap G formed by the first and second magnetic shields 14 and 16, and the minute signal magnetic field Hs from the magnetic storage medium reaches only the gap G formed by the first and second magnetic shields 14 and 16. - and the small signal magnetic field Hs Id in the region of the second magnetic shields 14 and 16
It is absorbed by the two magnetic shields. Therefore, the jog MR element in the gear G detects only the minute signal magnetic field Hs that reaches the gap G, making it possible to provide an MR head with excellent high frequency characteristics.

As described above, the magnetic head using the jog MR element of the present invention solves all the drawbacks of the conventional barber pole MR element. That is, whereas the barber pole MR element has the disadvantage that the detection area of the signal magnetic field is narrowed due to the presence of the strip-shaped electric conductor, and the electrical resistance is also reduced, the present invention has the disadvantage that the detection area of the signal magnetic field is actually reduced in any way. On the contrary, it is increased compared to conventional MR elements, and the total electrical resistance of the MR element is also increased, resulting in a large change in resistance that contributes to the output.

Furthermore, since the easy magnetization direction of the Jonog MR element, that is, the direction of magnetization M, is uniquely determined only by the direction of the groove,
An MR head with good reproducibility can be provided.

[Brief explanation of drawings]

Fig. 1 is a diagram showing the relationship between the sense current and magnetization M of the MR element, and its resistance change. Figs. 2 to 4 are schematic diagrams showing the configuration of a conventional MR element. In the example, the same figure (
(a) is a schematic oblique view showing the shape of the MR element, (b) is a plan view showing the relationship between magnetization 1 (and current flow) of the MR element, and
The figures are a schematic perspective view showing the groove shape of another embodiment of the present invention, FIG. 7 is a schematic perspective view showing an embodiment of bias means for aligning the direction of magnetization M of the MB element of the present invention, and FIG. 1 is a schematic perspective view showing an embodiment in which the MR element of the present invention is applied to a magnetically shielded MR head. In the figure, 1, 8, 10, 11, 12 are MR elements, 4
5 is the substrate material, 5 is the groove, 9 is the electrical terminal, 14 and 15 are the -
and a second magnetic shield. (b) Figure 2 Figure 6 Figure 7

Claims (1)

[Claims] 1. A ferromagnetic magnetoresistive element is provided on a magnetic substrate having one or more mutually parallel linear grooves (or convex portions), and the grooves (or convex portions) and the strong The angle between the magnetoresistive element and the flow or current is between 30 degrees and 60 degrees. A magnetoresistive head characterized in that the magnetoresistive head is set at a degree. 2. The magnetoresistive head according to claim 1, wherein the axis of easy magnetization of the ferromagnetic magnetoresistive element is forcibly provided substantially parallel to the groove (or convex portion). . . 3. Ferromagnetic magnetoresistance effect! ,Child? The lining direction is the groove (
2. The magnetoresistive head according to claim 1, further comprising a bias means such as φ, which is substantially parallel to the convex portion or the convex portion. 4. The magnetoresistive head according to claim 1, wherein the ferromagnetic magnetoresistive element is sandwiched between two magnetic shields made of a high permeability magnetic material. 5. The magnetoresistive head according to claim 3, wherein the biasing means is a conductor bias method. 6. The magnetoresistive head according to claim 3, wherein the biasing means is a hard film bias method. 7. The magnetoresistive head according to claim 3, wherein the biasing means is a permanent magnet provided outside the magnetoresistive head.