JPH08111010A - Multilayer magnetoresistive film and magnetic head - Google Patents

Abstract

(57) [Summary] [Structure] As a material of the non-magnetic layer 14 of the multilayer film, an alloy in which a noble metal element or Ru or Al is added to Cu is used. This improved the corrosion resistance of the non-magnetic layer 14. In addition, a high magnetoresistance change rate was maintained by limiting the addition amount of elements. Further, the multilayer magnetoresistive effect film was used for a magnetoresistive effect element, a magnetic head and a magnetic recording / reproducing apparatus. [Effect] The multilayer magnetoresistive effect film exhibits a high magnetoresistance change rate and corrosion resistance. Moreover, the magnetic head using the multilayer magnetoresistive film showed excellent reproducing characteristics. Further, a high performance magnetic recording / reproducing apparatus was obtained by using the magnetic head in the magnetic recording / reproducing apparatus.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer magnetoresistive effect film having a high magnetoresistive effect, a magnetoresistive effect element using the same, a magnetic head and a magnetic recording / reproducing apparatus.

[0002]

2. Description of the Related Art As the magnetic recording density increases, a material having a high magnetoresistive effect is required as a magnetoresistive effect material used for a reproducing magnetic head. So, Physical Review B by Dieny et al.,
"Giant Magnetoresistance Effect in Soft Magnetic Multilayer Films", Vol. 43, No. 1, pp. 1297-1300 (Giant Ma
gnetoresistance in Soft Ferromagnetic Multilayers)
As described above, a method of magnetically separating two magnetic layers with a non-magnetic layer and applying an exchange bias magnetic field from an antiferromagnetic layer to one magnetic layer has been devised. In this multilayer film, the electric resistivity is low when the magnetization directions of the two magnetic layers are parallel, and the electric resistivity is high when the magnetization directions are antiparallel. The magnetoresistive effect is generated by changing the angle formed by the magnetization directions of the two magnetic layers depending on the height of the applied magnetic field. In such a multilayer film, European Patent, 0 490 608 A2
As described in (1), Cu, Ag, and Au are used as the nonmagnetic layer.

[0003]

However, the C of the non-magnetic layer is
It is known that u has poor corrosion resistance. Further, it is difficult to form the Ag layer thinly and uniformly. Therefore, in order to magnetically separate the two magnetic layers with the Ag nonmagnetic layer,
It is necessary to increase the average layer thickness of the Ag non-magnetic layer,
As a result, the rate of change in magnetic resistance decreases. Also, Au is expensive and is disadvantageous for cost reduction.

It is an object of the present invention to provide a method for solving the problem in a high magnetoresistive effect multilayer film for a magnetoresistive effect type head.

[0005]

The inventors of the present invention have conducted extensive studies on a magnetoresistive effect element using a multilayer magnetic film in which non-magnetic layers having various materials and film thicknesses are laminated, and as a result, the multilayer film It was found that a multilayer film having a high magnetoresistance change rate and excellent corrosion resistance can be obtained by using an alloy in which various elements are added to Cu as the non-magnetic layer material in (1), and has completed the present invention.

That is, a plurality of magnetic layers are divided by nonmagnetic layers, and an exchange bias magnetic field from the antiferromagnetic layer is applied to at least one magnetic layer, and at least one magnetic layer is separated from the antiferromagnetic layer. In the multilayer magnetoresistive effect film using the multilayer film to which the exchange bias magnetic field is not directly applied, the corrosion resistance of the nonmagnetic layer is improved by using the alloy in which the precious metal element is added to Cu as the nonmagnetic layer. .
Further, by setting the addition amount of the noble metal element within a certain range, the decrease in the magnetoresistance change rate of the multilayer film can be minimized. In addition to the precious metal element, Ru,
Al is used.

[0007]

By using an alloy in which various elements are added to Cu as the non-magnetic layer material in the multilayer film, the high magnetoresistance change rate obtained when using the Cu non-magnetic layer is not significantly impaired, and the non-magnetic layer Corrosion resistance can be improved. Furthermore, the multilayer magnetoresistive effect film is suitable for a magnetoresistive effect element, a magnetic field sensor, a magnetic head, and the like. Also,
A high-performance magnetic recording / reproducing apparatus can be obtained by using the magnetic head.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings.

Example 1 The following experiment was conducted to improve the corrosion resistance of Cu used as the non-magnetic layer.

First, an alloy film prepared by adding various elements to Cu was formed on a glass substrate by an ion beam sputtering apparatus. The film thickness was 40 to 60 nm. The sputtering conditions, the ultimate vacuum 8~10 / 10 ⁵ Pa, Ar gas pressure 0.02 Pa, an ion gun acceleration voltage 300 V, and the ion current 30 mA.

A corrosion resistance test was conducted on the formed alloy film under the conditions of a temperature of 60 ° C. and a humidity of 90% for 3 days. The ratio of the area of the corroded portion to the total area of the alloy film after the corrosion resistance test was measured. The measurement results are shown in FIGS.

When a noble metal is added to Cu as shown in FIGS. 1 and 2, corrosion resistance is improved. Ag or Au addition amount is 3 at% or more, Pt, Ir, Pd addition amount is 5 at%
As described above, the corrosion resistance is improved when the added amount of Rh is 2 at% or more. Further, as shown in FIG. 3, the corrosion resistance is improved when the added amount of Ru is 2 at% or more and the added amount of Al is 5 at% or more.

As described above, noble metal, Ru, Al is added to Cu.
Addition improves the corrosion resistance. Therefore, it is preferable to use these alloys as the non-magnetic layer of the multilayer film.

[Embodiment 2] FIG. 4 shows a laminated structure of a multilayer film. In this example, a Si (100) single crystal substrate was used as the substrate 11. As the buffer layer 12, Hf having a thickness of 5 nm was used. The magnetic layers 13 and 15 have a thickness of 5
nm Ni-16 at% Fe-18 at% Co alloy was used. The antiferromagnetic layer 16 is made of Fe-40at having a thickness of 5 nm.
% Mn alloy was used. The protective layer 17 is made of Hf having a thickness of 5 nm.
Was used. Further, the nonmagnetic layer 14 uses the various alloys described in the first embodiment. The thickness of the nonmagnetic layer 14 is 2.5 nm.

FIG. 5 shows the relationship between the magnetoresistance change rate of the multilayer film and the additive element concentration when an alloy obtained by adding Au or Ag to Cu is used as the nonmagnetic layer. As shown in FIG. 5, the rate of change in magnetoresistance decreases as the concentration of the additional element increases. C
The reason why the magnetoresistance change rate decreases when Ag is added to u is considered as follows. When the amount of Ag added increases, the thickness of the non-magnetic layer becomes non-uniform, and the exchange interaction between the magnetic layers becomes stronger in the thin portion of the non-magnetic layer. Therefore, it is considered that the angle formed by the magnetizations of the two magnetic layers is less likely to change and the rate of change in magnetoresistance decreases. The reason why the magnetoresistance change rate decreases when Au is added to Cu is that the electric resistance of the multilayer film increases by the addition of Au.

As described above, when Au or Ag is added to Cu, the magnetoresistive change rate of the multilayer film decreases. 2%
In order to maintain the above magnetoresistance change rate, the amount of Au or Ag added should be 50 at% or less and 25a, respectively.
It needs to be t% or less. Therefore, in order to obtain excellent corrosion resistance and a high magnetoresistance change rate, the additive element concentrations of Au and Ag are set to 3 to 50 at% and 3 to 25 at%, respectively.
Must be set to%.

FIG. 6 shows the results when Pt, Ir, Rh, and Pd were added to Cu, and FIG. 7 shows the results when Ru and Al were added to Cu. 1 to 3 and 5 to 7
From the results, in order to obtain excellent corrosion resistance and a high rate of change in magnetoresistance, the composition of Pt with respect to Cu is 5 to 30 at.
%, Ir composition to Cu is 5 to 30 at%, Rh composition to Cu is 2 to 30 at%, Pd to Cu is
Composition of 5 to 30 at% and composition of Ru to Cu of 2
30at%, Al composition to Cu is 5 to 20at%
It is necessary to

In this embodiment, the non-magnetic layer of the binary alloy is described, but another element may be added as long as the magnetoresistance change rate of the multilayer film or the corrosion resistance of the non-magnetic layer is not impaired. But there is no problem.

In this embodiment, the magnetic layer is made of Ni-
Although the Fe-Co alloy is used, the same result can be obtained by using other magnetic layers. However, the magnetic layer to which the exchange bias magnetic field is not directly applied from the antiferromagnetic layer needs to exhibit soft magnetism.
It is preferable to use an i-Fe-based alloy or a Ni-Fe-Co-based alloy.

Further, in this embodiment, as the antiferromagnetic layer,
Although the Fe-Mn-based alloy was used, other antiferromagnetic materials can also be used. Antiferromagnetic materials are Cr-Mn, Pt-
Mn, Ir-Mn, Pd-Mn, Au-Mn, Ni-M
n, Ni-Cr-Mn-based alloy, Ni-O, Ni-Co-
O and the like are preferable.

Example 3 A magnetoresistive effect element using the multilayer film of the present invention was formed. In this example, Hf having a thickness of 5 nm was used as the buffer layer. The magnetic layer has a thickness of 5n
m Ni-16 at% Fe-18 at% Co alloy was used. The non-magnetic layer has a thickness of 2.5 nm Cu-25 at%.
Au alloy was used. Fe with a thickness of 10 nm is used for the antiferromagnetic layer.
A -40 at% Mn alloy was used. Further, Hf having a thickness of 5 nm was used for the protective layer.

FIG. 7 shows the structure of the magnetoresistive effect element. The magnetoresistive effect element has a structure in which the multilayer magnetoresistive effect film 21 and the electrode 22 are sandwiched by shield layers 23 and 24. When a magnetic field was applied to the magnetoresistive effect element and a change in electric resistivity was measured, it was found that the magnetoresistive effect element using the multilayer magnetoresistive effect film of the present invention has an applied magnetic field of about 1.6 kA / m (20 Oe). The rate of change in magnetic resistance was about 2.5%. The reproduction output of the magnetoresistive effect element of the present invention is Ni-F.
e 2.3 times higher than that of a magnetoresistive element using a single layer film.

In this embodiment, Cu is used as the non-magnetic layer material.
Although a -25 at% Au alloy was used, all the non-magnetic layer materials in the composition range of the present invention can be used as the non-magnetic layer of the multilayer film for the magnetoresistive effect element.

[Embodiment 4] Using the magnetoresistive effect element described in Embodiment 3, a magnetic head was manufactured. The structure of the magnetic head is shown below. FIG. 9 is a perspective view when a part of the recording / reproducing separated type head is cut. The portion of the multilayer magnetoresistive film 51 sandwiched by the shield layers 52 and 53 functions as a reproducing head, and the lower magnetic pole 55 and the upper magnetic pole 56 that sandwich the coil 54 function as a recording head. Further, a material having a multilayer structure of Cr / Cu / Cr is used for the electrode 58.

A method of manufacturing this head will be described below.

A sintered body containing Al ₂ O ₃ .TiC as a main component was used as the substrate 57 for the slider. A Ni-Fe alloy formed by a sputtering method was used for the shield layer and the recording magnetic pole. The thickness of each magnetic film was as follows. The upper and lower shield layers 52 and 53 were 1.0 μm, the lower magnetic pole 55 and the upper magnetic pole 56 were 3.0 μm, and the gap material between the layers was Al ₂ O ₃ formed by sputtering. The film thickness of the gap layer was 0.2 μm between the shield layer and the magnetoresistive element, and 0.4 μm between the recording magnetic poles. Further, the distance between the reproducing head and the recording head is set to about 4 μm, and this gap is also made of Al ₂
Formed with O ₃ . Cu having a film thickness of 3 μm was used for the coil 54.

When recording / reproducing was performed with the magnetic head having the structure described above, a reproducing output 2.3 times higher than that of the magnetic head using the Ni--Fe single layer film was obtained. It is considered that this is because the magnetic head of the present invention uses a multilayer film having a high magnetoresistive effect.

The magnetoresistive effect element of the present invention can also be used in a magnetic field detector other than the magnetic head.

[Embodiment 5] Using the magnetic head of the present invention described in Embodiment 4, a magnetic disk device was manufactured. The structure of the device is shown in FIG. For the magnetic recording medium 71, a material made of a Co—Ni—Pt—Ta alloy having a residual magnetic flux density of 0.75T was used. The track width of the magnetic head 73 is 2.5.
μm. Since the magnetoresistive effect element in the magnetic head 73 has a high reproduction output, a high-performance magnetic disk device which does not burden the signal processing was obtained.

[0030]

EFFECTS OF THE INVENTION In a multilayer film in which an exchange bias magnetic field from an antiferromagnetic layer is applied to a part of a magnetic layer, by using an alloy in which various elements are added to Cu as a nonmagnetic layer material, a Cu nonmagnetic layer is used. It is possible to improve the corrosion resistance of the non-magnetic layer without significantly impairing the high rate of change in magnetoresistance obtained when using. Furthermore, the multilayer magnetoresistive effect film is suitable for a magnetoresistive effect element, a magnetic field sensor, a magnetic head, and the like. Further, by using the magnetic head, a high performance magnetic recording / reproducing device can be obtained.

[Brief description of drawings]

FIG. 1 is a characteristic diagram of a corrosion resistance test when Ag, Au, and Pt are added to Cu.

FIG. 2 is a characteristic diagram of a corrosion resistance test when Ir, Rh, and Pd are added to Cu.

FIG. 3 is a characteristic diagram of a corrosion resistance test when Ru and Al are added to Cu.

FIG. 4 is a sectional view showing the structure of the multilayer magnetoresistive effect film of the present invention.

FIG. 5 is a characteristic diagram showing a magnetoresistance change rate of a multilayer film when Ag and Au are added to Cu.

FIG. 6 is a characteristic diagram showing a magnetoresistance change rate of a multilayer film when Pt, Ir, Rh, and Pd are added to Cu.

FIG. 7 is a characteristic diagram showing a magnetoresistance change rate of a multilayer film when Ru and Al are added to Cu.

FIG. 8 is a perspective view showing the structure of a magnetoresistive effect element using the multilayer magnetoresistive effect film of the present invention.

FIG. 9 is a perspective view showing the structure of the magnetic head of the present invention.

FIG. 10 is an explanatory diagram of a magnetic recording / reproducing apparatus of the present invention.

[Explanation of symbols]

11 ... Substrate, 12 ... Buffer layer, 13, 15 ... Magnetic layer,
14 ... Nonmagnetic layer, 16 ... Antiferromagnetic layer, 17 ... Protective layer.

Claims (13)

[Claims] 1. A two-layer magnetic layer is divided into non-magnetic layers, an exchange bias magnetic field from an antiferromagnetic layer is applied to one magnetic layer, and the one magnetic layer is separated from the antiferromagnetic layer. In the multilayer magnetoresistive effect film using a multilayer film to which the exchange bias magnetic field is not directly applied, the nonmagnetic layer is made of Cu.
A multilayer magnetoresistive effect film, which is an alloy in which a noble metal element is added to. 2. The multilayer magnetoresistive film according to claim 1, wherein the alloy obtained by adding a noble metal element to Cu is a Cu—Ag alloy, and the composition of Ag with respect to Cu is 3 to 25 at%. 3. The multilayer magnetoresistive effect film according to claim 1, wherein the alloy obtained by adding a noble metal element to Cu is a Cu—Au alloy, and the composition of Au with respect to Cu is 3 to 50 at%. 4. The multilayer magnetoresistive effect film according to claim 1, wherein the alloy obtained by adding a noble metal element to Cu is a Cu—Pt alloy, and the composition of Pt with respect to Cu is 5 to 30 at%. 5. The multilayer magnetoresistive film according to claim 1, wherein the alloy obtained by adding a noble metal element to Cu is a Cu—Ir alloy, and the composition of Ir with respect to Cu is 5 to 30 at%. 6. The multilayer magnetoresistive film according to claim 1, wherein the alloy obtained by adding a noble metal element to Cu is a Cu—Rh-based alloy, and the composition of Rh with respect to Cu is 2 to 30 at%. 7. The multilayer magnetoresistive film according to claim 1, wherein the alloy in which a noble metal element is added to Cu is a Cu—Pd alloy, and the composition of Pd with respect to Cu is 5 to 30 at%. 8. The two magnetic layers are divided by non-magnetic layers, and the exchange bias magnetic field from the antiferromagnetic layer is applied to the one magnetic layer, and the one magnetic layer is the antiferromagnetic layer. In the multilayer magnetoresistive effect film using the multilayer film to which the exchange bias magnetic field is not directly applied, the nonmagnetic layer is an alloy in which Ru is added to Cu, and the composition of Ru to Cu is 2 to A multi-layer magnetoresistive effect film having a content of 30 at%. 9. The two magnetic layers are divided by non-magnetic layers, and the exchange bias magnetic field from the antiferromagnetic layer is applied to one magnetic layer, and the one magnetic layer is the antiferromagnetic layer. In the multilayer magnetoresistive effect film using the multilayer film to which the exchange bias magnetic field is not directly applied, the nonmagnetic layer is an alloy in which Al is added to Cu, and the composition of Al to Cu is 5 to A multi-layered magnetoresistive effect film having a content of 20 at%. 10. A magnetoresistive effect element in which the multilayer magnetoresistive effect film according to claim 1 is partially used. 11. A magnetic head including a part of the magnetoresistive effect element according to claim 10. 12. A composite magnetic head in which the magnetoresistive effect element according to claim 10 and an inductive magnetic head are combined. 13. A magnetic recording / reproducing apparatus using the magnetic head according to claim 11 or 12.