JPH11273030A - Magneto-resistance effect type magnetic head - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the fluctuation in a reproduced output even though the width of a reproducing track and the reproducing gap are made narrower by setting the relationships among the reproducing track width, the reproducing gap film thickness, the residual magnetization film thickness product of a permanent magnet film and the saturated magnetization film thickness product of magnetically sensitive layer to specific regions. SOLUTION: The magneto-resistance effect type magnetic head is provided with the reproducing element having a magneto-resistance effect and the permanent magnet film which applies a longitudinal bias magnetic field to the element. Let the reproducing track width be TW (μm), the reproducing gap film thickness be GI (μm), the residual magnetization film thickness product of the permanent magnet film be Mrt (memu/ cm<2> ) and the saturated magnetization film thickness product of the magnetically sensitive layer be Mst (memu/cm<2> ). Then, the permanent magnet film and the magnetically sensitive layer are made to satisfy the relationships of equations I and II and the reproducing track width is set to <=1.5 μm and the reproducing gap length is set to <=0.2 μm. By having the structure, which satisfies the range above, the permanent magnet film applies a sufficient amount of magnetic flux to the magnetically sensitive layer even though the reproducing track width and the reproducing gap length are made narrower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic head used in a magnetic recording apparatus such as a hard disk drive and a VTR, and more particularly to a permanent magnet film, a reproducing gap, and a reproducing track width which constitute a reproducing element of the magnetic head. Related to the configuration.

[0002]

2. Description of the Related Art The miniaturization and large capacity of magnetic recording devices such as hard disk drives and VTRs are progressing at a rapid pace. In response to these trends, the performance of magnetic heads has been improved, and from electromagnetic induction type thin film magnetic heads to anisotropic magnetoresistive heads (hereinafter, AMR heads) utilizing thin film magnetoresistive effect phenomena. Further, it has evolved into a spin valve type magnetoresistive head (hereinafter referred to as SV head).
A conventional AMR head is disclosed in, for example, a known document IEEE Tr.
ans. Magn. Vol26 (1990) pp168
9 That is, a magnetoresistive element (hereinafter, MR element) for reproducing a magnetic signal on a magnetic recording medium is:
The structure is such that the MR element is sandwiched by a shield magnetic film that magnetically shields the MR element via a read gap film made of a nonmagnetic material. On the other hand, a magnetic pole for recording a magnetic signal on a magnetic recording medium uses an inductive magnetic head and has a structure laminated on a shield magnetic film.

In order to increase the areal recording density in a magnetic recording apparatus, it is essential to improve the linear recording density and the track density. In order to improve the track density, it is necessary to reduce the reproduction track width. In order to improve the linear recording density, the gap length of the recording head is reduced in order to narrow the recording bits, or the flying height between the recording head and the recording medium is reduced, so that finer bits are reduced. Although it is necessary to write data on the magnetic recording medium, the reproduced output tends to decrease as the frequency becomes higher due to the interference effect of the reproduced output waveform. To prevent this, a magnetic head having a structure in which a reproducing element is sandwiched between shields has come to be used. Here, the reproducing element refers to a structure including the MR element and involved in the reproducing operation of the magnetic head.

Incidentally, an MR element used as a reproducing element is easily affected by a domain wall or a magnetic domain structure generated in the MR element, and it is necessary to control Barkhausen noise. As one of the control means, for example, IEEE Trans. Ma
gn. Vol. 32 (1996) pp19, using a permanent magnet film adjacent to the MR element,
There is a method of applying a bias magnetic field to the element. The applied bias magnetic field can reduce the influence of the demagnetizing field generated at the end of the MR element in the track width direction, and can suppress generation of magnetic domains in the MR element.

[0005] For example, with respect to the technology disclosed above, a technology defining specific materials for permanent magnets is disclosed in US Pat.
4826. In this technology, CoCrPt, CoCrTa, Co
It is made of a material such as CrTaPt and CoCrPtB. As a characteristic of such a material, the product of the residual magnetization and the film thickness at a film thickness of 500 to 600 A is 2.38 to 3.78 (m
emu / cm ² ).

The influence of the magnetic characteristics of the permanent magnet film on the characteristics of the magnetoresistive head is described below.
It has been found that by improving the coercive force characteristics of the permanent magnet film as in the technique disclosed in JP-A-7-93714, Barkhausen noise and variations in the reproduction output of the magnetic head can be reduced.

[0007]

However, since the bias magnetic field generated by the permanent magnet film is a technique for suppressing and stabilizing the magnetization rotation of the reproducing element, the track width is reduced to improve the track density. And the distance between the adjacent permanent magnet films becomes smaller, and the effect of suppressing the magnetization rotation by the bias magnetic field tends to increase. For this reason, the sensitivity of the reproducing element further decreases, and there is a concern that the reproducing output may decrease. Further, when the shield interval is reduced to improve the linear recording density, the magnetic flux from the permanent magnet film is absorbed by the upper shield and the lower shield as shown in FIG.
Since no longitudinal bias magnetic field is applied to the element, the instability of the reproduction output cannot be controlled. Therefore, in order to control the reproduction output instability such as Barkhausen noise and obtain a magnetic head having a high reproduction output, use a permanent magnet film having characteristics corresponding to the reproduction track width and the reproduction gap length depending on the recording density. is necessary.

[0008]

According to the present invention, there is provided a magneto-resistance effect type magnetic head comprising a reproducing element having a magneto-resistance effect and a permanent magnet film for applying a longitudinal bias magnetic field to the reproducing element. The reproduction track width is Tw (μm), the reproduction gap film thickness is Gl (μm), and the residual magnetization film thickness product of the permanent magnet film is Mrt (memu / c).
m ² ), and the product of the saturation magnetization thickness of the magnetosensitive layer is Mst (memu /
cm ² ), the relationship between the reproduction track width, the reproduction gap film thickness, the product of the residual magnetization film thickness of the permanent magnet film, and the product of the saturation magnetization film thickness of the magnetosensitive layer is as follows: Mrt / Mst <= 0.0649 Tw ^{3 / 2} /Gl+1.92 (1) Mrt / Mst> = 0.0317Tw ^3/2 /Gl+1.07 (2) The reproduction track width is 1.5 μm or less, and the reproduction gap length is 0. It is characterized by being 2 μm or less.

Here, the reproduction track width represents the size of the reproduction element in the track width direction. The reproduction gap length refers to the distance between the upper shield and the lower shield near the reproducing element. Here, the upper shield and the lower shield are arranged so as to sandwich the read element via the read gap film. The reproduction gap film thickness represents a value of the sum of the thicknesses of the reproduction gap films in a direction perpendicular to the track width direction or a value obtained by subtracting the thickness of the permanent magnet film from the reproduction gap length near the reproducing element. The magneto-sensitive layer is a layer for detecting a magnetic signal. In the case of an AMR head, it indicates an MR layer, and in the case of an SV head, it indicates a free layer.

In the magnetoresistive head of the present invention,
The squareness ratio S = Mr / Ms given by the ratio between the residual magnetization Mr and the saturation magnetization Ms of the permanent magnet film is 0.6 or more and 1.0 or less.

In the magnetoresistive head according to the present invention, the permanent magnet film is an alloy containing Co as a main component, and Cr, Ta, P
It is a permanent magnet film containing at least one of t and Ni.

Further, in the magneto-resistance effect type magnetic head according to the present invention, the reproducing element having the magneto-resistance effect is constituted by two soft magnetic films laminated with a non-magnetic metal spacer interposed therebetween.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG.
The range of the magnetization ratio Mrt / Mst desirable for controlling the instability of the reproduction output is shown with respect to Tw ^3/2 / Gl defined by w (μm) and the reproduction gap film thickness Gl (μm). Here, the product of the residual magnetization thickness of the permanent magnet film is represented by Mrt (me
mu / cm ² ) and the product of the saturation magnetization thickness of the free layer as Mst (m
emu / cm ² ). The magneto-resistance effect type magnetic head of the present invention includes a reproducing element having a magneto-resistance effect and a permanent magnet film for applying a longitudinal bias magnetic field to the reproducing element, and the permanent magnet film and the magneto-sensitive layer are shown in FIG. 1) Equation and (2)
The following formula is satisfied: Mrt / Mst <= 0.0649 Tw ^3/2 /Gl+1.92 (1) Mrt / Mst> = 0.0317Tw ^3/2 /Gl+1.07 (2) 0.5 μm
Hereinafter, the reproduction gap length is set to 0.2 μm or less. By using a configuration that satisfies the above range, a sufficient amount of magnetic flux can be applied to the magnetosensitive layer from the permanent magnet film even when the reproduction track width and the reproduction gap length are reduced.

Hereinafter, the configuration of the present invention will be described step by step with reference to the drawings. FIG. 2 is a sectional view of a reproducing element portion of the AMR head. Permanent magnet films are arranged at both ends of the MR element, and suppress generation of magnetic domains in the MR element by applying a bias magnetic field to the MR element. A structure in which both ends of the MR element are tapered and a permanent magnet film is laminated thereon as shown in FIG. 2 is generally called an abutted junction. The step of forming an abutted junction between the MR film 1 / spacer 2 / SAL 3 and the permanent magnet layer 7 is performed, for example, by a lift-off method as shown in FIG. Here, SAL indicates a proximity soft magnetic film. FIG.
In (a), first, a photosensitive resist 9 is coated on the SAL3 / spacer 2 / MR film 1, and then the SiO ₂ 1
0 is formed by sputtering or the like. Next, after an unnecessary portion of SiO ₂ 10 is removed by etching, RIE (Re
The resist is selectively etched by active ion etching or the like to form a shape as shown in FIG. Thereafter, a taper portion is formed by ion milling, and then a base film 6, a permanent magnet film 7, and an electrode film 8 are sequentially formed by sputtering or the like (FIG. 3C).
And SiO ₂ 10 are removed with an organic solvent or the like to form an abated junction (FIG. 3D).

The shape of the permanent magnet film thus formed is affected by the height of the photosensitive resist 9 and SiO ₂ 10, so that the film thickness gradually decreases as approaching the MR element. FIG. 4 schematically shows the distribution of the magnetic poles and the magnetic field of the permanent magnet film when the tip is narrowed. The magnetization of the permanent magnet film is performed in the Tw direction (direction of the reproduction track width) to the right in the drawing. When the tip is narrowed, a magnetic pole is generated on the surface, and thus such a distribution is obtained. The bias magnetic field that contributes to the magnetic domain control is determined by the amount of magnetic flux generated from the magnetic pole near the MR element, and the magnetic flux from the distant magnetic pole is absorbed by the upper shield and the lower shield, so that it hardly contributes to the magnetic domain control. FIG. 5 shows the amount of magnetic flux φ applied to the MR element in FIG.
Is a result obtained by numerical calculation as to how it changes depending on the position X where the magnetic pole appears. The origin is set to zero at the start point of the taper of the free layer. In the numerical calculation, the permeability and the magnetic pole were given to each mesh by a two-dimensional finite element method, and the amount of magnetic flux passing through the magnetosensitive layer was calculated. Table 1 shows the parameters used in the numerical calculations. Here, the reproduction track width was defined as shown in FIG. 4 at the center position in the x direction of the abutted joint surface of the magnetosensitive layer. The effective magnetic permeability of the MR film, SAL, and shield film is a value estimated in consideration of the influence of the demagnetizing field.

[0016]

Table 1 The reproduction track width was 1.0 μm.

As shown in FIG. 5, the amount of magnetic flux applied from the permanent magnet to the magneto-sensitive layer decreases as the position of the magnetic pole moves away from the abutted joint surface. In particular, when X becomes larger than 50 nm, the amount of magnetic flux applied to the magneto-sensitive layer sharply decreases. This is probably because the magnetic flux was absorbed by the shield side. For reference, FIG. 5 also shows changes in the amount of magnetic flux when there is no shield. As described above, since only the permanent magnet near the MR element can effectively apply the longitudinal bias to the magnetosensitive layer when the shield is provided, in the following description, as shown in FIG. It is defined as the film thickness at a position 50 nm (X = 50 nm) from the tapered portion. Further, the film thickness T _PM permanent magnet at the position of the reproduction gap thickness Gl is X = 50 nm from the interval Gs of the upper and lower shield with respect to the perpendicular line across the starting point of the taper (X = 0 nm) as shown in FIG. It is defined as follows with the subtracted value. Gl = Gs-T _PM

When the track width decreases, the distance between adjacent permanent magnets decreases, the effect of the vertical bias increases, and the reproduction output decreases. When the shield interval Gs is reduced in order to improve the linear recording density, the magnetic flux from the permanent magnet is absorbed by the upper and lower shields, so that the longitudinal bias magnetic field is not effectively applied to the magneto-sensitive layer and the reproduction output becomes unstable. I can't control it. This indicates that the Mrt of the permanent magnet film has a lower limit necessary for controlling the reproduction instability and an upper limit which can ensure the reproduction output. Further, even when the Mrt of the permanent magnet is constant, the amount of magnetic flux per unit sectional area of the magnetosensitive layer decreases as the film thickness of the magnetosensitive layer increases. Mrt
(Mrt / Mst) is an appropriate index. In the following description, Mrt / Mst will be referred to as a magnetization ratio.

In the hard disk drive, inversion of magnetization recorded on a medium is used for recording and reproducing codes of 0 and 1. The change in the magnetic field due to the reversal of the magnetization in the medium is converted into the codes of 0 and 1 by reproduction by the magnetoresistive magnetic head. For example, when the code arrangement is continuous such as {0000}, the magnetization reversal cycle is Is long and conversely $ 1
When 1 is continuous as in 111 °, the cycle of magnetization reversal becomes short. In code reproduction currently used in hard disk devices, the ratio of the lowest frequency to the highest frequency has a relationship of 1: 5 to 1: 6, but the reproduction output tends to decrease as the frequency increases due to the interference effect of the reproduction waveform. At this time, the intensity ratio between the reproduced output for the highest frequency and the reproduced output for the lowest frequency is about 25 to 35%. On the other hand, the reproduction output from the head is required to be about 0.1 mV in order to reproduce the code without error in the hard disk device. Therefore, the reproduction output in the low frequency range is preferably at least 0.3 to 0.4 mV. Therefore, in the present invention, the reproduction output in the low frequency range is set to 0.
The magnetization ratio was set so that 4 mV or more could be secured.

Using the materials and shapes shown in Table 2, an MR head was manufactured with a permanent magnet having a magnetization ratio of 0.5 to 3.2, and the relationship between the hysteresis of the reproduced waveform and the reproduced output was examined. The reproduction output was measured at a low frequency by assembling the MR head after depth processing into a suspension and then flying above the recording medium. The hysteresis was measured by measuring a resistance change curve when an external magnetic field of ± 150 Oe was applied, and was defined as an area surrounded by a path when the magnetic field increased and when the magnetic field decreased as shown in FIG. In the head in which the hysteresis as shown in FIG. 6 occurs, the reproduction output fluctuates every time the recording / reproducing operation is performed, so that the drive error rate deteriorates.
FIG. 7 shows the relationship between the magnetization ratio and the reproduction output. It was found that the reproduction output decreased as the magnetization ratio increased. Since the reproduction output needs to be 0.4 mV or more at a low frequency as described above,
From this result, it is understood that in order to obtain a reproduction output of 0.4 mV or more, the magnetization ratio must be 2.3 or less. FIG. 8 shows the relationship between the magnetization ratio and the hysteresis. It has been known that hysteresis generally appearing in a reproducing element causes a variation in reproduced output and becomes a noise source of a disk drive device. Therefore, it is desirable that the hysteresis is as small as possible. As shown in FIG. 8, when the magnetization ratio is 1.5 or less, the hysteresis increases rapidly. Therefore, to suppress the hysteresis, the magnetization ratio of 1.5 or more is required. 7 and 8, the value of the magnetization ratio satisfying both the reproduction output and the hysteresis is 1.5 ≦
It is represented by a magnetization ratio ≦ 2.3.

[0021]

Table 2 Shape and material properties of the prototype MR head Reproduction track width 1.4 μm Reproduction gap film thickness Gl 0.15 μm MR height 0.8 μm

In the present invention, the relationship between the reproducing gap film thickness Gl of the actual head, the reproducing track width Tw, the Mrt of the permanent magnet film, and the Mst of the magneto-sensitive layer is defined by numerical calculation. It is necessary to deal with characteristics.
FIG. 9 shows the result of calculating the amount of magnetic flux applied to the magneto-sensitive layer from the permanent magnet when performing a numerical calculation using the parameters in Table 2. It can be seen that the amount of magnetic flux φ increases in proportion to the increase in the magnetization ratio. 7 and 8, it is desirable that the range of 1.5 <magnetization ratio <2.3 is satisfied, and the corresponding magnetic flux amount φ corresponds to the range of 7.7 <φ <11.8 (3). Therefore, in the subsequent calculations, the lower and upper limits of the magnetization ratio when Tw and Gl are changed are defined based on the magnetic flux amount of the equation (3).

According to the present invention, there is provided any one of the magnetic heads described above, wherein the rectangular shape given by the ratio of the residual magnetization Mr and the saturation magnetization Ms of the permanent magnet film as the means for applying the magnetic bias. The magnetoresistive head is characterized in that the ratio S = Mr / Ms is 0.7 or more and 1.0 or less.

FIG. 10 shows the shape of the magnetoresistive magnetic head viewed from the air bearing surface. Reference numeral 7 denotes a permanent magnet film, 11 denotes a magnetoresistive element, 8 denotes an electrode for supplying a current to the reproducing element, and 15 denotes a recording magnetic pole. The reproducing element is magnetically shielded by 12 lower shield films and 13 upper shield films. For example, the saturation magnetization Ms of a permanent magnet material used for a magnetoresistive head as a thin film material is 450 to 800.
(Emu / cm ³ ). At this time, the squareness ratio S is 1
Then, the film thickness required to obtain Mrt of 1 (memu / cm ² ) is 120 to 220 (A). On the other hand, when the squareness ratio S is 0.1, 1 (memu / c
The required film thickness for obtaining Mrt of m ² ) is 1200 to 2
It reaches 200 (A), and both sides of the reproduction track of the reproduction element become thick. The shape around the reproducing element also affects the shape of the recording magnetic pole. In order to alleviate the shape effect around the reproducing element, it is necessary to flatten the surface on which the magnetic poles are arranged before forming the recording magnetic pole, or to keep the reproducing element shape flat. However, the flattening operation has disadvantages in that the number of man-hours for manufacturing the magnetic head increases and the cost increases. On the other hand, the technique for keeping the shape of the reproducing element itself flat is not required to perform an extra step, and the time required for forming the film can be shortened by thinning the permanent magnet film. Productivity can be improved.

The permanent magnet film acceptable in the present invention is (1)
(2) is determined by the values of Mst and Gl.
Mrt becomes very large as l decreases. For example, when Mst = 1 (emu / cm ³ ) at a magnetization ratio of 5, a permanent magnet requires Mrt of 5.0 (emu / cm ³ ), and a permanent magnet material having a saturation magnetization of 450 (emu / cm ³ ) Is used, the thickness of the permanent magnet film is given by the following relationship. (Permanent magnet film thickness) = 5.0 (memu / cm ² ) / Ms (emu / cm ³ ) = 5.0 (memu / cm ² ) / (450 (emu / cm ³ ) × S) Is obtained when the squareness ratio S = 1 and becomes 1111 (A). As the squareness ratio S decreases, the thickness of the permanent magnet film increases, and the squareness ratio becomes 0.7 at 0.7.
587 (A) and reaches 2222 (A) at a squareness ratio of 0.5. The element thickness of the magnetoresistive head is 500 to 600.
(A), and the level difference of the element portion to which the electrode for signal detection is added becomes about 2000 (A) when the squareness ratio is 0.7. This causes a distortion of the recording magnetic pole to reach 50% of the recording gap length.
In addition, the squareness ratio of the permanent magnet film is desirably 0.7 or more in order to significantly deteriorate the characteristics of the reproduction wavelength.

The present invention also provides the magnetic head described above, wherein the permanent magnet film is an alloy containing Co as a main component, and Cr, Ta, P
A magnetoresistance effect type magnetic head characterized by being a permanent magnet film containing at least one of t and Ni.

In order to control the Mrt of a permanent magnet film that generates a bias magnetic field with a magnetoresistive head and obtain good reproduction characteristics, it is necessary to obtain a permanent magnet material exhibiting excellent magnetic characteristics in a thin film state. . In the case of a permanent magnet film of an alloy containing Co as a main component, a coercive force Hc of 1000 Oe or more and a squareness ratio S of 0.7 or more can be ensured in a thickness range of 100 to 1000 (A).

According to the present invention, there is provided the magnetic head described above, wherein the reproducing element having a magnetoresistive effect is constituted by two soft magnetic films stacked via a nonmagnetic metal spacer. This is a characteristic magnetoresistive head.

In the present invention, a material such as Cu or Ta can be used as the nonmagnetic metal spacer. NiFe, Co, N
iFeCo, CoFe or the like can be used, and f
By having a crystal structure of cc, good soft magnetic characteristics can be obtained.

[0030]

[Embodiment] The magnetization ratio is set to 1.0 to
The dependence of the amount of magnetic flux φ applied from the permanent magnet film to the MR film on the reproduction gap film thickness Gl when changed at 5.0 was calculated. The results are shown in FIG. As shown in FIG. 11, it can be seen that the amount of magnetic flux φ applied to the magneto-sensitive layer sharply decreases as Gl decreases. For example, FIG. 12 shows the relationship between the magnetic flux amount and the set magnetization ratio when Gl is 0.09 μm, and it is understood that the magnetization ratio and the magnetic flux amount are almost proportional. Therefore,
When the upper limit and the lower limit of the magnetization ratio are defined based on the definition of the amount of magnetic flux in Expression (3), 1.96 <magnetization ratio <2.66. FIG.
(A), FIG. 13 (b) and FIG. 13 (c) show that the reproduction track width Tw is 1.4 μm, 0.95 μm and 0.5 μm, respectively.
The upper limit of the magnetization ratio with respect to the read gap length Gl,
Indicates the lower limit. Here, the vertical axis is the value of the magnetization ratio calculated backward from the magnetic flux amount, and the horizontal axis is the value of 1 / Gl. It can be seen that as the read gap length Gl decreases, the magnetic flux absorbed by the shield increases, so that the magnetization ratio must be increased. Conversely, when the reproduction track width Tw is narrow, it can be seen that by setting the magnetization ratio low, it is possible to manufacture a head with high output and little output variation. FIG. 13 (a), FIG.
13 (c), it is necessary to obtain a coefficient obtained by first-order approximation of the magnetization ratio and the value of 1 / Gl with respect to FIG. 13 (c), and calculate the minimum magnetization ratio and the maximum magnetization ratio as a function of Tw and Gl. Fitting with Tw ^3/2 / Gl was appropriate. FIG. 14 is a plot of FIG. 13 (a), FIG. 13 (b), and FIG. 13 (c) with Tw ^3/2 / Gl on the horizontal axis and the magnetization ratio on the vertical axis. From FIG. 14, Tw is 1.4 μm,
When the values are changed to 0.95 μm and 0.5 μm, almost the same tendency is obtained. Therefore, the magnetization ratio can be defined by the following equation as a function of Gl and Tw. Mrt / Mst <= 0.0599 Tw ^3/2 / Gl + 1.
86 Mrt / Mst> = 0.0362 Tw ^3/2 / Gl + 1.
12 If the magnetization ratio is set within this range, a stable MR head with a high reproduction output and little fluctuation can be manufactured.

In an actual head, the film thickness and the magnetic permeability may differ from each other, and a difference occurs in the amount of magnetic flux applied to the MR film from the permanent magnet. Therefore, the amount of magnetic flux is calculated small (the same amount of magnetic flux cannot be obtained unless the magnetization ratio is increased)
Table 3 shows the numerical value of the other, and Table 4 shows the numerical value of the case where the magnetic flux amount is calculated to be large (the same magnetic flux amount can be obtained even if the magnetization ratio is small). In the following calculations, two calculations were performed using the numerical values in Tables 3 and 4.

[0032]

[Table 3] Calculation parameters (when the magnetization ratio is highly estimated)

[0033]

[Table 4] Calculation parameters (when underestimating the magnetization ratio)

FIG. 1 shows the calculation results. The ordinate plots the magnetization ratio, and the abscissa plots Tw ^3/2 / Gl. When the magnetization ratio is highly estimated (when the numerical values in Table 3 are used), (3)
The upper and lower limits of the magnetization ratio defined by the equation can be expressed by the following equation. ^{Mrt / Mst <= 0.0649Tw 3/2 /Gl+1.92(1} ) Mrt / Mst> = 0.0411Tw 3/2 / Gl + 1.
18 Similarly, when the magnetization ratio is estimated lower (when the numerical values in Table 4 are used), the upper and lower limits of the magnetization ratio defined by the expression (3) can be expressed by the following expressions. Mrt / Mst <= 0.0540Tw ^3/2 /Gl+1.81 Mrt / Mst> = 0.0317Tw ^3/2 /Gl+1.07 ( ² ) FIG. 1 shows a case where the film thickness, the magnetic permeability, etc. are different in the actual head. However, by setting the magnetization ratio within the range defined by the equations (1) and (2), the amount of magnetic flux satisfying the equation (3) can be applied to the magneto-sensitive layer, so that the reproduction output is high and the M
An R head can be manufactured.

[0035]

By using the magnetoresistive head of the present invention, it is possible to obtain good reproduction characteristics with little fluctuation in reproduction output and reproduction output even when the reproduction track width and reproduction gap become narrow.

[Brief description of the drawings]

FIG. 1 is a diagram showing ranges of a read track width, a read gap film thickness, and a magnetization ratio defined in the present invention.

FIG. 2 is a cross-sectional view of a reproducing element.

FIG. 3 is a schematic view of a step of forming an abutted junction.

FIG. 4 is a schematic diagram of a magnetic pole distribution of a permanent magnet film in a reproducing element portion.

FIG. 5 is a diagram showing a reduction in the amount of magnetic flux applied to a magneto-sensitive layer by a shield.

FIG. 6 is a diagram showing a definition of hysteresis seen in a reproduction output of an MR head.

FIG. 7 is a diagram showing a relationship between a magnetization ratio and a reproduction output.

FIG. 8 is a diagram showing a relationship between a magnetization ratio and hysteresis.

FIG. 9 is a diagram showing the relationship between the magnetization ratio and the amount of magnetic flux applied to the magneto-sensitive layer.

FIG. 10 is a schematic diagram of an MR head.

FIG. 11 is a view for explaining the dependence of the amount of magnetic flux applied to the magneto-sensitive layer on the thickness of the reproducing gap.

FIG. 12 is a diagram showing the relationship between the magnetization ratio and the amount of magnetic flux at Gl = 0.09 μm.

FIG. 13 is a view showing a specified range of a reproducing gap film thickness and a magnetization ratio.

FIG. 14 is a diagram showing a specified range of a read track width, a read gap film thickness, and a magnetization ratio.

[Explanation of symbols]

Reference Signs List 1 MR film, 2 spacer, 3 SAL, 4 upper gap film, 5 lower gap film, 6 base film, 7 permanent magnet film, 8 electrode film, 9 photosensitive resist, 10 SiO
₂ , 11 magnetoresistive element, 12 lower shield, 1
3 upper shield, 14 shield spacing, 15 upper magnetic pole, 16 recording coil.

Claims (4)

[Claims] In a magnetoresistive head having a reproducing element having a magnetoresistive effect and a permanent magnet film for applying a longitudinal bias magnetic field to the reproducing element, the reproducing track width is Tw (μm) and the reproducing gap film thickness is Gl (μm) and the product of the residual magnetization film thickness of the permanent magnet film is Mrt (memu / c
m ² ), and the product of the saturation magnetization thickness of the magnetosensitive layer is Mst (memu /
cm ² ), the relationship between the reproduction track width, the reproduction gap film thickness, the product of the residual magnetization film thickness of the permanent magnet film, and the product of the saturation magnetization film thickness of the magnetosensitive layer is as follows: Mrt / Mst <= 0.0649 Tw ^{3 / 2} /Gl+1.92 (1) Mrt / Mst> = 0.0317Tw ^3/2 /Gl+1.07 (2) The reproduction track width is 1.5 μm or less, and the reproduction gap length is 0. A magnetoresistive head having a thickness of 2 μm or less. 2. The magnetoresistance effect type magnetic head according to claim 1, wherein a squareness ratio S = Mr / Ms given by a ratio between a residual magnetization Mr and a saturation magnetization Ms of the permanent magnet film.
Is 0.6 or more and 1.0 or less. 3. The magneto-resistance effect type magnetic head according to claim 2, wherein the permanent magnet film is an alloy containing Co as a main component, and Cr, as an additive element to the alloy.
A magnetoresistive head comprising a permanent magnet film containing at least one of Ta, Pt, and Ni. 4. The magneto-resistance effect type magnetic head according to claim 3, wherein the reproducing element having a magneto-resistance effect is constituted by two soft magnetic films laminated via a non-magnetic metal spacer. A magnetoresistance effect type magnetic head characterized by the following.