JPH0798818A - Magneto-resistance effect type head - Google Patents

Abstract

PURPOSE:To provide the low-noise MR head by using quaternary soft magnetic thin films of Ni-Fe-Nb-Co which have the saturation magnetic flux density, anisotropic magnetic field, magneto-striction and specific resistance satisfying the conditions relating to the soft magnetic thin films of the MR head and can be made larger in the anisotropic magnetic field than an Fi-Fe alloy. CONSTITUTION:The soft magnetic thin films to be used for a a soft bias method is required to have the saturation magnetic flux density of 0.5 to 1.0T, the anisotropic magnetic field of 10 to 10Oe and the magneto-striction of -1X10<-6> to +1X10<-6>. The thin films are further required to have the specific resistance of >=60mumOMEGA.cm in a composite bias method. Alloy thin films consisting, by weight, of 30 to 90% Ni, 5 to 65% Fe, 5 to 15% Nb and 0 to 15% Co are used in order to form the alloy satisfying the magnetic and electric characteristics required for the soft magnetic thin films for impression of bias magnetic fields and having excellent corrosion resistance. The anisotropic magnetic field is made smaller than the anisotropic magnetic field of the films consisting of Nb and the magneto-resistriction moves to consisting of Nb and the magneto-resistriction moves to positive. The ferromagnetic element makes the saturation magnetic flux density and the anisotropic magnetic field larger. Since the magneto-resistriction changes as well, the addition of the ferromagnetic element smaller in the change of the specific resistance is more preferable and the adequate element is Co. The soft magnetic thin films adequate for the MR head are easily formed and the characteristics are easily adjusted by adding the Nb and the Co to the alloy thin films of the Ni-Fe system.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to Ni-Fe-Nb-C.
The present invention relates to a magnetoresistive head using an o-based alloy thin film.

[0002]

2. Description of the Related Art Generally, a magnetoresistive head (MR head) has a direction perpendicular to a surface opposing a recording medium (hereinafter referred to as an element height direction) in order to make a response to a leakage magnetic flux from a magnetic recording medium linear. It is used by applying a bias magnetic field. This bias magnetic field is often called a lateral bias magnetic field in order to compare it with the bias magnetic field for stabilizing the magnetic domain structure of the magnetoresistive effect element. As one of typical methods of applying a lateral bias magnetic field, Japanese Patent Laid-Open No.
There is a soft film bias method described in −65213. this is,
A soft magnetic thin film (soft film) is provided near the magnetoresistive film via a magnetic separation film, and the soft magnetic thin film is magnetized by the magnetic field created by the sense current flowing in the magnetoresistive film, and is generated from the magnetized soft magnetic thin film. A bias magnetic field is applied to the magnetoresistive film by the magnetic field. When a conductive thin film is used as the magnetic separation film, the magnetic field created by the sense current and the magnetic field generated from the soft magnetic thin film can be efficiently applied to the magnetoresistive film as described in JP-A-52-62417. . This method is referred to below as the composite bias method.

With these methods, the magnetic and electrical characteristics of the soft magnetic thin film have a great influence on the reproduction characteristics. The required characteristics are to have an appropriate size of saturation magnetic flux density,
The anisotropic magnetic field and the magnetostriction are small, and the composite bias method has a high specific resistance in addition to these. As a soft magnetic thin film satisfying these characteristics, Journal of Applied Physics, 69 (199)
1st year) Pages 5631 to 5633 (J. Appl. Phys., 69
(1991) 5631-5633), Ni-F
Thin films prepared by adding various non-magnetic third elements to an e-based alloy have been studied.

[0004]

Generally, when a non-magnetic third element is added to a Ni-Fe alloy, the saturation magnetic flux density and the anisotropic magnetic field become small and the specific resistance becomes large. But,
Magnetostriction is not simple because it may increase or decrease depending on the added element. Furthermore, even with the same additive element, the effect of improvement in each characteristic is different,
It is difficult to achieve optimum values for all characteristics with one type of additive element. Also, since the optimum values of the above-mentioned characteristics differ depending on the structure of the MR head, it is very difficult and labor-intensive to re-examine the type and amount of the element to be added to realize the optimum characteristics. It costs.

Further, as described above, when the non-magnetic third element is added to the Ni-Fe alloy, the anisotropic magnetic field becomes small, but the magnetic domain structure of the soft magnetic thin film becomes unstable depending on the structure of the MR head. Barkhausen noise may occur. In that case, in order to stabilize the magnetic domain structure, it is advantageous to use a soft magnetic thin film having a large anisotropic magnetic field.

An object of the present invention is that the saturation magnetic flux density, anisotropic magnetic field, magnetostriction and specific resistance can satisfy the conditions relating to the soft magnetic thin film of the MR head, and the anisotropic magnetic field is Ni-
N, which is a material that can be made larger than the Fe-based alloy
An object of the present invention is to provide an i-Fe-Nb-Co quaternary soft magnetic thin film, and apply the Ni-Fe-Nb-Co soft magnetic thin film to an MR head to realize an MR head with less Barkhausen noise.

[0007]

Means for Solving the Problems By adding Nb, which is a non-magnetic element, and Co, which is a magnetic element, to a Ni-Fe alloy thin film, it is required as a soft magnetic thin film used in a soft film bias method or a composite bias method. A thin film that satisfies the magnetic and electrical characteristics is obtained. As a soft magnetic thin film for the soft film bias method, Ni-Fe alloy thin film is 5.0 wt%
Ni containing the above Nb and 15.0 wt% or less Co
It is a -Fe-Nb-Co alloy thin film. The specific composition is 30 to 90% Ni, 5 to 65% Fe, 5 to 5% by weight.
It is an alloy composed of 15% Nb and 0 to 15% Co. At this time, it is necessary that the saturation magnetic flux density is in the range of 0.5 T or more and 1.0 T or less and the anisotropic magnetic field is in the range of 1 Oe or more and 10 Oe or less. Regarding magnetostriction,
It is desirable to be in the range of -1 × 10 ^-6 to + 1 × 10 ^-6 . In the case of the soft magnetic thin film in the composite bias method, a Ni-Fe-Nb-Co based alloy thin film having the above-mentioned magnetic properties and having a specific resistance of 60 μΩ · cm or more is used.

[0008]

[Function] The soft magnetic thin film used in the soft film bias method is
It is required to have a saturation magnetic flux density of 0.5 T or more and 1.0 T or less, an anisotropic magnetic field of 1 Oe or more and 10 Oe or less, a small magnetostriction, and a higher specific resistance in the composite bias method. Ni-Fe based alloy with non-magnetic third
When an element is added, the saturation magnetic flux density and the anisotropic magnetic field are decreased, and the specific resistance is increased. Therefore, in order to satisfy the characteristics of the soft magnetic thin film described above, the addition of the non-magnetic third element to the Ni-Fe alloy thin film I do. Here, Nb is one of the elements capable of satisfying the magnetic properties and electrical properties required for the soft magnetic thin film for applying a bias magnetic field and forming an alloy excellent in corrosion resistance. The addition of Nb reduces the anisotropic magnetic field, and the magnetostriction moves in the positive direction.

In order to adjust the above-mentioned characteristics to the optimum value, any one of the characteristics hardly changes even when the element is added, and the other three characteristics are changed by the addition of Nb. It is necessary to add an element having the opposite effect. The elements that can increase the saturation magnetic flux density and the anisotropic magnetic field are limited to ferromagnetic elements. Magnetostriction naturally changes with the addition of a ferromagnetic element, so it is desirable to add a ferromagnetic element with a small change in resistivity. Co is an element that forms an alloy that moves in the negative direction of magnetostriction with almost no change in specific resistance due to addition and that exhibits good corrosion resistance. Satisfies the above-mentioned required characteristics regarding the saturation magnetic flux density and anisotropic magnetic field, and satisfies the desirable values for magnetostriction and specific resistance in the range of -1 × 10 ^-6 to + 1 × 10 ^-6 , and 65 μΩ · cm or more. The amount of Nb and Co added is 5.0% by weight, respectively
And 15.0% by weight or less.

[0010]

EXAMPLES The present invention will be described in detail below with reference to examples.

Embodiment 1 FIG. 2 is a perspective view of a magnetoresistive head according to an embodiment of the present invention. The lower shield film 1 is formed on the non-magnetic substrate 10 on which an insulating layer such as alumina is formed into a thin film and precision-polished.
As No. 1, sendust was formed by sputtering, patterned into a predetermined shape by a photolithography technique, and an alumina insulating film 13 was formed thereon. NiFe 15 and FeMn 16 were laminated as a magnetic domain control layer and patterned into a predetermined shape. At this time, the magnetic domain control layer in the central portion of the magnetoresistive effect element is removed, and the exchange coupling between the portion where the magnetic domain control layer remains and the magnetoresistive effect film 17 and NiF.
The magnetic domain structure of the magnetoresistive effect film 17 is controlled by the magnetic field generated by e15. Next, as a magnetoresistive effect element portion using the composite bias method, permalloy as the magnetoresistive effect film 17, Ta as the nonmagnetic conductive thin film 18 and Ni-Fe-Nb-Co based alloy as the soft magnetic thin film 19 are used. Was formed by sputtering. In addition, Ni-Fe-N
The b-Co alloy thin film has a saturation magnetic flux density of 0.59 T, an anisotropic magnetic field of 4.8 Oe, a magnetostriction of -3.3 × 10 ^-7, and a specific resistance of 77.5 μΩ · cm. Cr as the protective film 20
After coating with C, using photolithography technology,
The r protective film, the magnetoresistive effect element portion, the magnetic domain control film, and the alumina insulating film were patterned into predetermined shapes. Further, the electrode 21 was formed by the dry etching method, and the alumina insulating film 14 was formed thereon and patterned.
After forming a resist as the protective film 22, an upper shield film 12 made of permalloy was formed and patterned. A photolithography technique was used for patterning the alumina insulating film 14 and the upper shield film 12. In order to magnetize the magnetic domain control layer, a heat treatment was performed at 275 ° C. for 30 minutes while applying a DC magnetic field of 3 kOe in the track width direction, and then processed into a magnetoresistive head of a predetermined size.

In this embodiment, the upper and lower shield films are provided in order to obtain a head with high resolution, but they may not be provided if high resolution is not required. Further, if the magnetoresistive film can be formed flat, it is not always necessary to form it from the magnetic domain control film, and it may be formed from the electrode. Furthermore, in the magnetic domain control film, in addition to FeMn, R is added to FeMn.
An antiferromagnetic material such as Fe—Mn-based alloy or NiO added with u, Rh, Ti, Cr or the like, or a permanent magnet material such as Co—Pt-based alloy or Co—Cr-based alloy can be used.

With respect to the magnetoresistive head manufactured as described above, the magnetoresistive change curve was measured, and the rotation angle (hereinafter referred to as the bias angle) from the direction in which the sense current of the magnetization of the magnetoresistive film flows. For comparison, as a soft magnetic thin film, the saturation magnetic flux density, the magnetostriction and the specific resistance are almost the same as those of the present embodiment, and the anisotropic magnetic field is Ni-Fe-, which is 1.5 Oe.
The same measurement was performed for the head using the Nb-based alloy. The measurement results are shown in FIG. The head using the Ni-Fe-Nb-Co alloy has a larger bias angle than the head using the Ni-Fe-Nb alloy.
Further, the coercive force is 1600 Oe, the magnetic film thickness t _mag = 20n.
m, product of residual magnetic flux density B _r and magnetic film thickness B _r · t _mag = 1
A recording pattern recorded at 5 kFCI using an induction type thin film magnetic head having an overwrite characteristic of 32 dB on an 80 G · μm Co-Ta-Cr sputter medium was reproduced at a flying height of 0.15 μm and a sense current of 10 mA, and then reproduced. Evaluated the output. The reproducing output of the head using the Ni-Fe-Nb-Co alloy is 305 μV, whereas the reproducing output of Ni-
270 μV in the head using the Fe-Nb alloy
Met. The difference between these characteristics is that NiF of the magnetic domain control layer
Ni-Fe having a small anisotropic magnetic field due to the magnetic field from e
The magnetization direction of the -Nb alloy thin film is the same as that of the magnetoresistive effect film, but Ni-Fe-N having a large anisotropic magnetic field is used.
This is probably because the b-Co alloy thin film faces in the opposite direction. Barkhausen noise was not observed in either head. Therefore, in the structure of FIG. 2, it can be said that the Ni--Fe--Nb--Co based alloy used as the soft magnetic thin film exhibits superior head characteristics.

Embodiment 2 FIG. 3 is a perspective view of a magnetoresistive head according to another embodiment of the present invention. Permalloy is formed as a lower shield film 11 by sputtering on the non-magnetic substrate 10 on which an insulating layer such as alumina is formed into a thin film and precision-polished.
It was patterned into a predetermined shape by a photolithography technique, and an alumina insulating film 13 was formed thereon. After NiO 23 was laminated as a magnetic domain control layer and patterned into a predetermined shape, alumina which was the high resistance thin film 24 was formed into a predetermined shape by a lift-off method. On top of that, permalloy which is the magnetoresistive film 17, Ta which is the non-magnetic conductive thin film 18 and Ni-Fe-Nb-C which is the soft magnetic thin film 19 are formed.
The o-based alloy was formed by sputtering. At this time,
The control of the magnetic domain structure of the magnetoresistive effect film 17 is performed by utilizing the exchange coupling between the magnetic domain effect control film NiO 23 and the magnetoresistive effect film 17. As the Ni-Fe-Nb-Co alloy thin film, two types of thin films having the characteristics shown in Table 1 were used. The electrode 21 was formed by the lift-off method, and the alumina insulating film 14 was formed thereon and patterned.
After forming a resist as the protective film 22, the upper shield film 12 made of permalloy was formed and patterned. A photolithography technique was used for patterning the alumina insulating film 14 and the upper shield film 12. In order to magnetize the magnetic domain control layer, heat treatment was performed at 275 ° C. for 30 minutes while applying a DC magnetic field of 3 kOe in the track width direction,
A magnetoresistive head having a predetermined size was processed.

Although alumina is used as the high-resistance thin film 24 in this embodiment, Ta, tantalum oxide, tantalum nitride, or the like can also be used.

With respect to the magnetoresistive head manufactured as described above, the bias angle and the reproduction output were evaluated in the same manner as in Example 1. Sense current 10mA
Table 1 shows the evaluation results of the above. Regarding Barkhausen noise, 10 heads were measured and the number of heads where Barkhausen noise was observed is shown. Ni-Fe-N
Barkhausen noise is observed in the b-based alloy, and the higher the step due to the alumina, which is the high-resistance thin film 24, the higher the probability of its appearance. On the other hand, Ni-Fe-Nb-
Since no Barkhausen noise was observed in the Co-based alloy, in the case of the Ni-Fe-Nb-based alloy, the anisotropic magnetic field was small, so the direction of the magnetization was disturbed by the step, and as a result, Barkhausen noise was generated. It seems that it is easier to do. Ni-Fe-Nb-Co based alloys have a positive magnetostriction and an anisotropic magnetic field of about 5 Oe (NiFeNb
Co 1) and one having a negative magnetostriction and an anisotropic magnetic field of about 7 Oe (NiFeNbCo 2) were used. When the thickness of the high resistance thin film 24 of alumina is 10 nm, NiFeNbCo 1 exhibits better head characteristics, and when it is 30 nm, NiFeNbCo 2 exhibits better characteristics. When the thickness of alumina is small, the magnetization of the soft magnetic thin film is hard to rotate when the anisotropic magnetic field is too large, and it is considered that a sufficient bias magnetic field cannot be applied to the magnetoresistive film. On the other hand, when the thickness of alumina is large, it is considered that the stress is generated by the step and the magnetization of NiFeNbCo 2 is easier to rotate due to the effect of magnetostriction.

[0017]

[Table 1]

Example 3 A Ni—Fe—Nb—Co alloy thin film having a large specific resistance was used as the soft magnetic thin film with the same film structure as in Example 2 except for the soft magnetic thin film. It is expected that the use of the soft magnetic thin film having a large specific resistance will increase the current flowing through the magnetoresistive film and improve the reproduction output. The applied Ni—Fe—Nb—Co alloy thin film has the following characteristics: saturation magnetic flux density of 0.54 T, anisotropic magnetic field of 6.2 Oe, and magnetostriction of −.
The specific resistance is 4.2 × 10 ⁻⁷ and 110 μΩ · cm. The bias angle and the reproduction output of the magnetoresistive head processed into a predetermined size were evaluated in the same manner as in Example 1. For comparison, Co is used as a soft magnetic thin film.
The same measurement was performed for a magnetoresistive head using a Ni-Fe-Nb alloy thin film to which no was added.
The characteristics of the Ni-Fe-Nb alloy thin film are that the saturation magnetic flux density is 0.41 T, the anisotropic magnetic field is 1.0 Oe, and the magnetostriction is +.
3.7 × 10 ⁻⁷ , the specific resistance is almost the same as that of the present embodiment 108
It is μΩ · cm. The bias angle and the read output at a sense current of 10 mA were 45 degrees and 450 μV, respectively, in the magnetoresistive head using the Ni—Fe—Nb—Co alloy thin film, while the Ni—Fe—Nb alloy thin film was used. The head using the
It was V. The difference between these characteristics is that Ni-Fe-Nb
-Since the saturation magnetic flux density is higher in the Co-based alloy thin film,
It is considered that this is because the bias magnetic field applied to the magnetoresistive film is large.

Example 4 Similar to Example 3, Ni-Fe-Nb- having the same structure as Example 2 except for the soft magnetic thin film and having a different composition only in the soft magnetic thin film.
A Co-based alloy thin film was used. Specifically, the saturation magnetic flux density,
An Ni-Fe-Nb-Co alloy thin film having a large specific resistance is applied in a range satisfying the characteristics of anisotropic magnetic field and magnetostriction. The characteristics are that the saturation magnetic flux density is 0.50T, the anisotropic magnetic field is Is 8.5 Oe, magnetostriction is −5.2 × 10 ⁻⁷ , and specific resistance is 125 μΩ · cm. The bias angle and the reproduction output of the magnetoresistive head processed into a predetermined size were evaluated in the same manner as in Example 1. For comparison, the same measurement was performed for a magnetoresistive head using a Ni—Fe—Nb alloy thin film having a saturation magnetic flux density almost equal to that of this embodiment as a soft magnetic thin film. The characteristics of the Ni-Fe-Nb alloy thin film are that the saturation magnetic flux density is 0.50 T, the anisotropic magnetic field is 1.7 Oe, and the magnetostriction is +.
The specific resistance is 4.4 × 10 ⁻⁷ and 82.0 μΩ · cm. The bias angle and reproduction output at a sense current of 10 mA are
The magnetoresistive head using the Ni-Fe-Nb-Co alloy thin film has a temperature of 40 degrees and 480 μV, respectively, whereas the head using the Ni-Fe-Nb alloy thin film has a temperature of 38 degrees and 400 μV, respectively. there were. It is considered that the difference in these characteristics is due to the fact that the Ni—Fe—Nb—Co alloy thin film has a larger specific resistance, so that the current flowing through the magnetoresistive effect film increases.

[0020]

According to the present invention, the saturation magnetic flux density, anisotropic magnetic field, magnetostriction and specific resistance of Nd-Fe alloy thin film added with Nb and Co are required characteristics of the soft magnetic thin film used in the MR head. It is possible to easily form a thin film satisfying the above conditions, and it is possible to adjust these characteristics relatively easily. Therefore, by using a Ni-Fe-Nb-Co alloy thin film having optimum characteristics depending on the structure of the MR head, M with a large reproduction output without Barkhausen noise.
An R head is obtained.

[Brief description of drawings]

FIG. 1 shows the sense current dependence of the bias angle.

FIG. 2 is a perspective view of a magnetoresistive head according to an embodiment of the present invention.

FIG. 3 is a perspective view of a magnetoresistive head according to another embodiment of the present invention.

[Explanation of symbols]

10 ... Non-magnetic substrate, 11 ... Lower shield film, 12 ... Upper shield film, 13, 14 ... Alumina insulating film, 15 ... Ni
Fe film, 16 ... FeMn film, 17 ... Magnetoresistive film, 1
8 ... Nonmagnetic conductive film, 19 ... Soft magnetic thin film, 20 ... Protective film, 21 ... Electrode, 22 ... Resist protective film, 23 ... NiO
Membrane, 24 ... High resistance thin film.

Claims (7)

[Claims] 1. A magnetoresistive effect film, a soft magnetic thin film located near the magnetoresistive effect film and magnetically separated from the magnetoresistive effect film by a magnetic separation film, and a current flowing through the magnetoresistive effect film. In a magnetoresistive head having an electrode for flowing, the soft magnetic thin film comprises 30 to 90% by weight of Ni, 5 to 65% of Fe, 5 to 15% of Nb, and 0 to 15 by weight.
% Magnetoresistive head, which is an alloy thin film made of Co. 2. The magnetoresistive head according to claim 1, wherein the alloy thin film is a thin film formed by a sputtering method or a vapor deposition method. 3. The alloy thin film according to claim 1, wherein the alloy thin film is 0.5.
A magnetoresistive head having a saturation magnetic flux density of T or more and 1.0 T or less. 4. The alloy thin film according to claim 1, wherein the alloy thin film is 1 Oe.
A magnetoresistive head having an anisotropic magnetic field of 10 Oe or less. 5. The alloy thin film according to claim 1, wherein the alloy thin film is -1 ×.
A magnetoresistive head having a magnetostriction within the range of 10 ^-6 to + 1 × 10 ^-6 . 6. The alloy thin film according to claim 1, wherein the alloy thin film is 0.5.
It has a saturation magnetic flux density of T or more and 1.0 T or less, an anisotropic magnetic field of 1 Oe or more and 10 Oe or less, and from -1 × 10 ^-6 to +
A magnetoresistive head having a magnetostriction within the range of 1 × 10 ⁻⁶ . 7. The magnetoresistive head according to claim 1, wherein the magnetic separation film is a conductive thin film, and the alloy thin film has a specific resistance of 60 μΩ · cm or more.