JPH08241506A - Multilayer magnetoresistive film and magnetic head - Google Patents

Abstract

PURPOSE: To obtain a multilayered film having high heat resistance without considerably deteriorating magnetoresistance variation by forming a Co-noble metal alloy layer at the interface between each of two magnetic layers and a nonmagnetic layer. CONSTITUTION: A (100) single crystal substrate of Si is used as a substrate 11. An Hf layer of 5nm thickness is used as a buffer layer 12, Ni-19 atomic % Fe alloy layers of 4nm thickness are used as magnetic layers 13, 17 and Co-Pt alloy layers of 1nm thickness are used as magnetic layers 14, 16. A Cu layer of 2.5nm thickness is used as a nonmagnetic layer 15, an Fe-40 atomic % Mn alloy layer of 5nm thickness is used as an antiferromagnetic layer 18 and an Hf layer of 5nm thickness is used as a protective layer 19. A layer of an alloy of Co with <=25 atomic % noble metal selected from among Pt, Pd, Rh and Ir is formed at the interface between each of the magnetic layers 14, 16 and the nonmagnetic layer 15. The objective multilayered film having high heat resistance is obtd. without considerably deteriorating magnetoresistance variation.

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. At present, the magnetoresistance change rate of permalloy used is about 3%, and it is necessary for the new material to have a magnetoresistance change rate higher than this.

Physical Review B (Pysical Revi
ew B), Vol. 43, No. 1, pp. 1297-1300, "Giant magnetoresistance effect in soft magnetic multilayer film (Giant
Magnetoresistance in Soft Ferromagnetic Multil
ayers) ”, the two magnetic layers are separated by a non-magnetic layer,
A method of applying an exchange bias magnetic field from the antiferromagnetic layer to one magnetic layer has been devised. In such a multilayer film, EP
As described in (European Patent) 0 490 608 A2, in order to adjust the structure, crystal grain size, etc. of the multilayer film, T is formed on the substrate.
A buffer layer made of a, Ru, Cr, V is formed.

In addition, the Japanese Journal of
Applied Physics (Japanese Journal of Appl
ied Physics), Vol. 33, No. 1A, 133-137.
"Fe-using various buffer layer materials"
Magnetoresistance and crystalline orientation in Mn / Ni-Fe / Cu / Ni-Fe sandwich film
Preffered Orientation in Fe-Mn / Ni-Fe /
Cu / Ni-Fe Sandwiches with Various Buffer L
ayer Materials) ”, the two layers of magnetic layers are separated by a non-magnetic layer, and the crystal orientation of the multilayer film is determined by applying the exchange bias magnetic field from the antiferromagnetic layer to one magnetic layer. Hf, Zr, Ti, Ta, Nb to control
To form a buffer layer.

Applied Physics Letter (Appl
ied Physics Letters), Volume 62, 1478-148
“Effect of annealing on t interface of giant magnetoresistive spin valve structure” on page 1
he interface of giant-magnetoresistance spin-valv
e structure)), the two magnetic layers are divided into non-magnetic layers, and the exchange bias magnetic field from the antiferromagnetic layer is applied to one magnetic layer. The heat treatment reduces the rate of change in magnetoresistance.

In addition, as described in "Giant Magnetoresistance of Spin-Valve Laminated Film Using NiO Antiferromagnetic Film" described in Journal of Applied Magnetics, Vol. 18, No. 2, pp. 355-359, two layers In the multi-layered film using the method of dividing the magnetic layer by the non-magnetic layer and applying the exchange bias magnetic field from the antiferromagnetic layer to one magnetic layer, in the case of the multi-layered film using Ni-Fe as the magnetic layer, In the case of a multilayer film in which a Co layer is formed at the interface between the Ni—Fe magnetic layer and the non-magnetic layer at 200 ° C. or higher, the magnetoresistive effect is lowered by the heat treatment at 250 ° C. or higher.

[0007]

In the manufacturing process of the magnetoresistive head, the magnetoresistive film goes through a heating process. Therefore, the multilayer magnetoresistive effect film is desired to have high heat resistance.

An object of the present invention is to provide a method for solving the problem of heat resistance in a multilayer magnetoresistive effect film.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies on a magnetoresistive effect element using a multilayer magnetic film in which magnetic layers and nonmagnetic layers having various materials and film thicknesses are laminated, and as a result, It was found that by forming an alloy layer of Co and a noble metal at the interface between the magnetic layer and the non-magnetic layer, heat resistance can be improved without significantly deteriorating the magnetic characteristics of the multilayer magnetoresistive effect film, The present invention has been completed.

That is, a plurality of magnetic layers are divided by non-magnetic layers, 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. The exchange bias magnetic field of is not directly applied in the magnetoresistive film using the multilayer film,
At the interface between the magnetic layer and the non-magnetic layer, Co, Pt, Pd, R
By forming an alloy with a noble metal selected from h and Ir and setting the concentration of the noble metal in the alloy to 25 at% or less, the heat resistance can be improved without significantly decreasing the magnetoresistance change rate of the multilayer film. it can. Further, by forming a buffer layer composed of a group IVa metal element and a group Va metal element on the periodic table between the multilayer film and the substrate, the multilayer film formed on the buffer layer has a (111) orientation. Indicates. At this time, the interaction between the magnetic layers is magnetically separated, and the exchange bias magnetic field from the antiferromagnetic layer is sufficiently applied to the magnetic layer.

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 above magnetic head, a high performance magnetic recording / reproducing apparatus can be obtained.

[0012]

As described above, in the multilayer magnetoresistive effect film in which the two magnetic layers are divided by the nonmagnetic layer and the exchange bias magnetic field from the antiferromagnetic layer is applied to one magnetic layer, the magnetic layer and the nonmagnetic layer are separated. By forming an alloy layer of Co and a noble metal selected from Pt, Pd, Ir, and Rh at the interface with the layer and setting the concentration of the noble metal in the alloy layer to 25 at% or less, the magnetoresistance change rate is significantly reduced. It is possible to improve the heat resistance without doing so. 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 above magnetic head, a high performance magnetic recording / reproducing apparatus can be obtained.

[0013]

【Example】

<Example 1> An ion beam sputtering method was used for manufacturing the multilayer film. The ultimate vacuum is 3/10 ⁵ Pa, and the Ar pressure during sputtering is 0.02 Pa. Also,
The film formation rate is 0.01 to 0.02 nm / s. The cross-sectional structure of the formed multilayer film is shown in FIG. Si on the substrate 11
A (100) single crystal substrate was used. In addition, the buffer layer 12
As the material, Hf having a thickness of 5 nm was used. For the magnetic layers 13 and 17, a Ni-19 at% Fe alloy having a thickness of 4 nm was used. In addition, the magnetic layers 14 and 16 have a C thickness of 1 nm.
An o-Pt alloy was used and its composition was changed. For the non-magnetic layer 15, Cu having a thickness of 2.5 nm was used. Further, for the antiferromagnetic layer 18, a Fe-40 at% Mn alloy having a thickness of 5 nm was used. Further, the protective layer 19 has a thickness of 5 nm of Hf.
Was used.

FIG. 2 shows the change in the magnetoresistance change rate with respect to the Pt concentration. As shown in the figure, the Pt concentration is 0 at% (pure C
In the case of o), the magnetoresistance change rate is 4.7%. Although the magnetoresistive change rate slightly decreases as Pt is added, the magnetoresistive change rate is as high as 4.2% even in the case of the multilayer film in which Pt is added at 25 at%. If Pt is further added, the rate of change in magnetoresistance sharply decreases.

In FIG. 3, the Pt concentration is 0, 17, 29 at
The dependence of the magnetoresistance change rate with respect to the heat treatment temperature in the multilayer film using the Co—Pt layer of which the content is% is shown. Hold the sample in the vacuum at the specified temperature for 1 hour,
After cooling in a magnetic field of Oe, the magnetoresistance change rate was measured at room temperature. As shown in the figure, as Pt is added, the heat treatment temperature at which the rate of change in magnetoresistance starts to decrease becomes higher.

As described above, in order to improve the heat resistance without greatly reducing the magnetoresistance change rate, the Pt concentration is set to 2
It must be 5 at% or less.

In this embodiment, H is used as the buffer layer 12.
f was used. When X-ray diffraction was performed on the multilayer film,
All of these multilayer films showed a (111) crystal orientation. When a multilayer film without the buffer layer 12 was prepared, the multilayer film did not exhibit (111) crystal orientation, and the magnetoresistive effect did not appear. In order to obtain a multilayer film having a high magnetoresistance change rate, it is necessary that the multilayer film exhibits a (111) orientation. Also,
In the buffer layer 12, another IVa metal element on the periodic table, Va
Similar results can be obtained by using a non-magnetic alloy containing a metal element as a main component.

When Barkhausen noise is generated in the magnetoresistive effect curve, a mechanism for applying a bias magnetic field in a direction perpendicular to the magnetic field detection direction of the multilayer magnetoresistive effect film is effective in suppressing Barkhausen noise. There is.
When the magnetoresistive film is used for a narrow track magnetic head having a track width of 1 μm or less, the track width needs to be strictly defined. Therefore, the mechanism for applying the bias magnetic field is that the exchange bias magnetic field is directly applied from the antiferromagnetic layer. A method in which the antiferromagnetic layer or the hard magnetic layer is brought into contact with the portion of the magnetic layer to which no voltage is applied is preferable.

Further, in this embodiment, the magnetic layers 13 and 1 are
Although a Ni—Fe alloy was used as No. 7, even if a magnetic layer having another face-centered cubic structure is used, the changes in the magnetization curve and the magnetoresistive effect curve due to the buffer layer material are the same.
However, the magnetic layer to which the exchange bias magnetic field is not directly applied from the antiferromagnetic layer needs to exhibit soft magnetism,
For the magnetic layer, it is preferable to use a Ni—Fe based alloy or a Ni—Fe—Co based alloy.

Although Cu is used for the non-magnetic layer 15 in this embodiment, the same result can be obtained by using an alloy containing Cu as a main component. However, when a 3d transition metal is used for the magnetic layer, the non-magnetic layer is preferably Cu from the viewpoint of matching the Fermi surface with the magnetic layer.

In this embodiment, the Fe-Mn alloy is used as the antiferromagnetic layer 18, but other antiferromagnetic materials can be used. As an antiferromagnetic material, Fe-M
An alloy in which a corrosion resistance improving element is added to the n-based alloy and the Fe-Mn-based alloy is preferable. As the alloy in which the corrosion resistance improving element is added to the Fe—Mn alloy, a Fe—Mn—Ru alloy is preferable from the viewpoint of corrosion resistance and high Neel temperature. In addition, other Mn-based metal alloys such as Mn-Co and Mn-
Ni, Mn-Pd, Mn-Pt, Mn-Rh, Mn-I
An antiferromagnetic metal such as r can also be used.

Example 2 A multilayer film was formed by the same method as in Example 1. A Si (100) single crystal substrate was used as the substrate 11 in FIG. The thickness of the buffer layer 12 is 5n.
m Hf was used. The magnetic layers 13 and 17 have a thickness of 4
nm Ni-19 at% Fe alloy was used. Further, for the magnetic layers 14 and 16, an alloy obtained by adding 20 at% of a noble metal to Co was used, and the thickness was set to 1 nm. A for precious metals
u, Ag, Pt, Pd, Ir and Rh were used. For the non-magnetic layer 15, Cu having a thickness of 2.5 nm was used. Further, for the antiferromagnetic layer 18, a Fe-40 at% Mn alloy having a thickness of 5 nm was used. Further, the protective layer 19 has a thickness of 5 nm of Hf.
Was used. For comparison, films using pure Co for the magnetic layers 14 and 16 were also prepared at the same time.

FIGS. 4 and 5 show the dependence of the magnetoresistance change rate on the heat treatment temperature in the multilayer films of this example and the comparative example. When nothing is added to Co, the magnetoresistance change rate starts to decrease at around 250 ° C., whereas Co and Au and A
When g is added, the rate of change in magnetoresistance does not decrease significantly up to around 280 ° C. Furthermore, Pt, Pd, and I are added to Co.
When r and Rh are used, the magnetoresistance change rate does not decrease significantly up to around 300 ° C. Thus, by forming the alloy layer of Co and the noble metal at the interface between the magnetic layer and the nonmagnetic layer, a magnetoresistive effect multilayer film having high heat resistance can be obtained.

Example 3 A multilayer film having the same structure as in Example 1 was produced. The substrate 11 was made of Si (100) single crystal. In addition, as the buffer layer 12, Z having a thickness of 5 nm is used.
r was used. A Ni-19 at% Fe alloy was used for the magnetic layer 13, and Co-20 at% Pt was used for the magnetic layer 14 so that the total thickness of the magnetic layers 13 and 14 would be 5 nm. The magnetic layer 17 has a thickness of 4 nm of Ni-19 at%.
An Fe alloy was used. The magnetic layer 16 has a thickness of 1 nm.
Co-20 at% Pt was used. In the non-magnetic layer 15,
Cu having a thickness of 2.5 nm was used. In addition, the antiferromagnetic layer 18
For this, an Fe-40 at% Mn alloy having a thickness of 10 nm was used. The protective layer 19 was made of Zr having a thickness of 5 nm.

FIG. 6 shows changes in the magnetoresistance change rate and the coercive force of the magnetic layer not in contact with the antiferromagnetic layer with respect to the thickness of the Co—Pt layer. As shown in the figure, the magnetoresistance change rate is Co-Pt.
The layer increases until it reaches a thickness of 1 nm, and it has a substantially constant value when the layer thickness is increased. Further, the coercive force of the magnetic layer not in contact with the antiferromagnetic layer increases with the thickness of the Co—Pt layer, and when the Co—Pt layer thickness exceeds 2 nm, the coercive force sharply increases.

As described above, in order to obtain a multilayer magnetoresistive effect film in which the magnetic layer not in contact with the antiferromagnetic layer has excellent soft magnetic characteristics and has a high magnetoresistance change rate, It is desirable that the thickness of the alloy layer of Co and the noble metal formed at the interface with the magnetic layer be 2 nm or less.

Example 4 A magnetoresistive effect element using the multilayer film of the present invention was formed. In this embodiment, the substrate 1 of FIG.
1 was a Si (100) single crystal substrate. As the buffer layer 12, Hf having a thickness of 5 nm was used. The magnetic layer 13 and the magnetic layer 17 have a thickness of 4 nm of Ni-19 at% F.
e alloy was used. The magnetic layer 14 and the magnetic layer 16 have a thickness of 1
nm Co-10 at% Pt was used. For the non-magnetic layer 15, Cu having a thickness of 2.5 nm was used. For the antiferromagnetic layer 18, a Fe-40 at% Mn alloy having a thickness of 10 nm was used. The protective layer 19 is made of Hf having a thickness of 5 nm.

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, the magnetoresistive effect element using the multilayer magnetoresistive effect film of the present invention showed 4.2% in an applied magnetic field of about 30 Oe.
The degree of magnetoresistance change was shown. Further, the reproduction output of the magnetoresistive effect element of the present invention was 3.6 times that of the magnetoresistive effect element using the Ni-Fe single layer film.

Example 5 A magnetic head was manufactured using the magnetoresistive effect element described in Example 4. The structure of the magnetic head is shown below. FIG. 8 is a perspective view when a part of the recording / reproducing separated type head is cut. The portion of the multilayer magnetoresistive effect film 31 sandwiched by the shield layers 32 and 33 functions as a reproducing head, and the portions of the lower magnetic pole 35 and the upper magnetic pole 36 that sandwich the coil 34 function as a recording head. The multilayer magnetoresistive effect film 31 is composed of the multilayer film described in the fifth embodiment. The electrode 38 is made of a material having a multi-layer structure of Cr / Cu / Cr.

The manufacturing method of this head will be described below.

A sintered body containing Al ₂ O ₃ .TiC as a main component was used as the substrate 37 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 32 and 33 were 1.0 μm, the lower magnetic pole 35 and the upper magnetic pole 36 were 3.0 μm, and the gap material between the layers was Al ₂ O ₃ formed by sputtering. The thickness of the gap layer is 0.2μ between the shield layer and the magnetoresistive effect element.
m between recording magnetic poles and 0.4 μm. Further, the distance between the reproducing head and the recording head was set to about 4 μm, and this gap was also formed of Al ₂ O ₃ . The coil 44 has a Cu film thickness of 3 μm.
It was used.

When recording / reproducing was performed with the magnetic head having the above-described structure, a reproducing output 3.5 times higher than that of a magnetic head using a Ni--Fe single layer film as a magnetoresistive effect element 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.

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

Further, by using the magnetic head in the magnetic recording / reproducing apparatus, a high performance magnetic recording / reproducing apparatus can be obtained.

<Embodiment 6> Using the magnetic head of the present invention described in Embodiment 5, a magnetic disk device was manufactured. FIG. 9 shows a schematic view of the structure of the magnetic disk device.

The magnetic recording medium 41 has a residual magnetic flux density of 0.1.
A material made of 75T Co-Ni-Pt-Ta alloy was used. The track width of the recording head of the magnetic head 43 was 3 μm, and the track width of the reproducing head was 2 μm.

In the figure, reference numeral 42 is a magnetic recording medium drive unit, 44 is a magnetic head drive unit, and 45 is a recording / reproducing signal processing system.

Since the magnetoresistive effect element in the magnetic head 43 exhibits an output about 3.5 times that of the conventional magnetoresistive effect element using the permalloy single layer film, the magnetic disk having a narrower track width and a higher recording density. The device can be made. The magnetic head of the present invention is particularly effective for a magnetic recording / reproducing device having a recording density of 1 Gb / in ² or more. Further, it is considered to be essential for a magnetic recording / reproducing apparatus having a recording density of 10 Gb / in ² or more.

[0039]

EFFECT OF THE INVENTION In a multilayer magnetoresistive film in which two magnetic layers are divided by a nonmagnetic layer and an antiferromagnetic layer is in contact with one magnetic layer, Pt and Pd are formed at the interface between the magnetic layer and the nonmagnetic layer. , Ir,
By forming an alloy layer of a noble metal selected from Rh and Co, the magnetoresistance change rate is not significantly deteriorated,
A multilayer film having high heat resistance can be obtained. 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 sectional view showing the structure of a multilayer magnetoresistive effect film of the present invention.

FIG. 2 is a graph showing the relationship between the Pt concentration of the Co—Pt layer and the magnetoresistance change rate.

FIG. 3 is a graph showing the relationship between the magnetoresistance change rate and the heat treatment temperature when the Pt concentration of the Co—Pt layer is changed.

FIG. 4 is a graph showing a relationship between magnetoresistance change rate and heat treatment temperature when various noble metals are added to Co.

FIG. 5 is a graph showing the relationship between the magnetoresistance change rate and the heat treatment temperature when various noble metals are added to Co.

FIG. 6 is a graph showing the relationship between the Co—Pt layer thickness, the magnetoresistance change rate, and the coercive force.

FIG. 7 is a perspective view showing the structure of a magnetoresistive effect element using the multilayer magnetoresistive effect film of the present invention.

FIG. 8 is a perspective view showing the structure of the magnetic head of the present invention.

FIG. 9 is an explanatory diagram of a structure of a magnetic recording / reproducing apparatus of the present invention.

[Explanation of symbols]

11 ... Si substrate, 12 ... Hf buffer layer, 13 ... Ni-
Fe magnetic layer, 14 ... Co-Pt magnetic layer, 15 ... Cu non-magnetic layer, 16 ... Co-Pt magnetic layer, 17 ... Ni-Fe magnetic layer, 18 ... Fe-Mn antiferromagnetic layer, 19 ... Hf protective layer .

Claims (11)

[Claims] 1. A plurality of magnetic layers are divided by non-magnetic layers, and an exchange bias magnetic field from an antiferromagnetic layer is applied to at least one magnetic layer, and the antiferromagnetic layer is applied to at least one magnetic layer. An exchange bias magnetic field from a layer is a magnetoresistive film using a multilayer film that is not directly applied, and a magnetoresistive film that produces a magnetoresistive effect depending on the angle between the magnetizations of the magnetic layers sandwiching the nonmagnetic layer. The multi-layered magnetoresistive film, wherein an alloy layer of Co and a noble metal is formed at the interface between the magnetic layer and the nonmagnetic layer. 2. The alloy layer of Co and a noble metal formed at the interface between the magnetic layer and the non-magnetic layer to which the exchange bias magnetic field from the antiferromagnetic layer is not directly applied according to claim 1. A multilayer magnetoresistive effect film having a film thickness of 2 nm or less. 3. The multilayer magnetoresistive effect film according to claim 1, wherein the concentration of the noble metal in the alloy of Co and the noble metal is 25 at% or less. 4. The Co according to claim 1, 2, or 3.
A magnetoresistive effect multilayer film in which the noble metal added to is a metal selected from Pt, Pd, Ir, and Rh. 5. The IVa group metal element on the periodic table, V between the multilayer film and the substrate according to claim 1, 2, 3 or 4.
A multilayer magnetoresistive effect film in which a buffer layer made of a non-magnetic alloy containing a group a metal element, a group IVa metal element or a group Va metal element as a main component is formed. 6. The method according to claim 1, 2, 3, 4 or 5.
The magnetic layer and the nonmagnetic layer have a face-centered cubic structure, and (1
11) Oriented multilayer magnetoresistive film. 7. A multilayer magnetoresistive film according to claim 1, 2, 3, 4, 5 or 6, wherein at least a part of said magnetic layer is a Ni—Fe based alloy or a Ni—Fe—Co based alloy. 8. The exchange bias magnetic field from the antiferromagnetic layer according to claim 1, 2, 3, 4, 5, 6 or 7, when the applied magnetic field including the multilayer magnetoresistive film is zero. Is a magnetoresistive element in which the direction of magnetization of the magnetic layer is orthogonal to the direction of magnetization of the magnetic layer to which the exchange bias magnetic field from the antiferromagnetic layer is not directly applied. A magnetoresistive effect element using a method of detecting a change in electric resistance caused by rotation of the magnetization direction of a magnetic layer to which an exchange bias magnetic field is not directly applied by an external magnetic field. 9. A magnetic head including the magnetoresistive effect element according to claim 8. 10. A composite magnetic head in which the magnetoresistive effect element according to claim 8 and an inductive magnetic head are combined. 11. A magnetic recording / reproducing apparatus using the magnetic head according to claim 9.