JPH0817631A - Multilayer magnetoresistive film and magnetic head - Google Patents

Abstract

PURPOSE:To provide a multilayered magnetoresistance effect film which shows excellent soft magnetic characteristics and heat resistance. CONSTITUTION:In a multilayered magnetoresistance effect film wherein a multilayered film containing two-layered magnetic layers 13, 15 divided by a non-magnetic layer 14 and an diaferromagnetic layer 16 for applying a switching bias magnetic field to the magnetic layer 15 out of the two-layered magnetic layers are formed on a substrate 11, a buffer layer 12 of alloy composed of group IVa element and group Va element in a periodic table is formed between the multilayered film and the substrate. Thereby the multilayered magnetoresistance effect film shows excellent soft magnetic characteristics and heat resistance. A magnetic head using the multilayered magnetoresistance effect film shows excellent reproducing characteristics.

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 Magnetoresist in Soft Magnetic Multilayer Films", Volume 43, No. 1, pp. 1297-1300.
ance in Soft Ferromagnetic Multilayers) 2
A method has been devised in which the magnetic layers of the layers are separated by a non-magnetic layer and the exchange bias magnetic field from the antiferromagnetic layer is applied to one of the magnetic layers. In the above-mentioned multilayer film, as described in EP, A2, 0 490 608, a buffer layer made of Ta, Ru, CrV is formed on the substrate in order to adjust the structure, crystal grain size, etc. of the multilayer film. are doing.

[0003]

DISCLOSURE OF THE INVENTION The present inventors have found that Ta as the buffer layer and V of the periodic table as well as Ta.
A multi-layer film having a cross-sectional structure shown in FIG. 1 was formed by using V and Nb which are group a elements. The ion beam sputtering method was used for manufacturing the multilayer film. Ultimate vacuum is 3 × 10 ^-5 P
a, Ar pressure during sputtering is 0.02 Pa. The film formation rate is 0.01 to 0.02 nm / s.
Is. The substrate 11 in FIG. 1 includes Si (10
0) A single crystal was used. The thickness of the buffer layer 12 is 5 nm. The magnetic layers 13 and 15 have a thickness of 3 nm of Ni-2.
A 0 at% Fe alloy was used. The nonmagnetic layer 14 has a thickness of 2n
m of Cu is used, and the antiferromagnetic layer 16 has a thickness of F of 5 nm.
An e-40 at% Mn alloy was used. As the protective layer 17, the same material as the buffer layer 12 was used with a film thickness of 5 nm.

The magnetoresistive effect curves of these multilayer films are shown in FIG.
Shown in As shown in FIG. 2, a large hysteresis is seen in the magnetoresistive effect curve of the multilayer film using the buffer layer made of V, Nb, and Ta. When a multilayer film is used for a magnetoresistive head, if the magnetoresistive curve has a large hysteresis, the output waveform of the magnetic head is distorted. Therefore, it is preferable that the hysteresis in the magnetoresistive effect curve of the multilayer film is small.

The coercive force of the magnetic layer 13 of these multilayer films in the easy magnetization direction was 3 to 5 Oe. When the coercive force of the magnetic layer 13 is high, the magnetoresistive effect element produces Barkhausen noise. Therefore, the coercive force of the multilayer magnetic layer 13 is required to be low. As described above, the multilayer film using V, Nb, and Ta which are Va group elements of the periodic table as the buffer layer 12 in FIG. 1 has a large hysteresis in the magnetoresistive effect curve. Moreover, the coercive force of the magnetic layer 13 is high.

Next, by using Ti, Zr, and Hf which are group IVa elements of the periodic table as the buffer layer 12 in FIG. 1, a magnetoresistive effect curve with a relatively small hysteresis is obtained as shown in FIG. [For this result, see Naka
Tani et al., Jpn. J. Appl. Phys., Vol. 33, No. 1A, 13
See “Using Various Buffer Layer Materials” on pages 3-137.
Magnetoresistance and Preferred Orientat of Fe-Mn / Ni-Fe / Cu / Ni-Fe Sandwich "
ion in Fe-Mn / Ni-Fe / Cu / Ni-Fe Sandwiches with Various
Buffer Layer Materials)). Further, the coercive force of the magnetic layer 13 in FIG. 1 in the easy magnetization direction was as low as 2.0 Oe, and the coercive force of the magnetic layer 13 in the difficult magnetization direction was 0.8 Oe.

By the way, when the multilayer film is used for a magnetoresistive head, the multilayer film goes through a heating process in the magnetic head manufacturing process. Therefore, the multilayer film is desired to have high heat resistance. However, as shown below,
As the buffer layer 12, Ti, Zr, and H which are group IVa elements
When a heat treatment was performed on the multilayer film using f at 305 ° C., the magnetoresistance change rate decreased to 0.2 to 0.3%.

Similarly to the above, a multilayer film having the cross-sectional structure of FIG. 1 was formed. The substrate 11 was made of Si (100) single crystal. The buffer layer 12 includes V, Nb, Ta, T
i, Zr, and Hf were used, and the film thickness was 5 nm. Magnetic layer 1
3 and 15 have a thickness of 5 nm of Ni-16 at% Fe-
A 18 at% Co alloy was used. Cu having a thickness of 2.5 nm was used for the non-magnetic layer 14. For the antiferromagnetic layer 16, a Fe-40 at% Mn alloy having a thickness of 5 nm was used. Protective layer 1
7 is made of the same material as the buffer layer 12 and has a thickness of 5 n.
m. Table 1 shows the relationship between the coercive force of the magnetic layer 13 in the easy magnetization direction and the buffer layer material.

[0009]

[Table 1]

As is clear from Table 1, as a buffer layer material, V, Nb, and T which are Va group elements in the periodic table.
When a is used, the coercive force of the magnetic layer 13 in the easy magnetization direction becomes high. On the other hand, when Ti, Zr, and Hf which are IVa group elements in the periodic table are used as the buffer layer material, the coercive force of the magnetic layer 13 in the easy magnetization direction is low. FIG. 4 shows the relationship between the heat treatment temperature and the magnetoresistance change rate for the multilayer film. As shown in the figure, when the heat treatment is performed at a temperature of 200 ° C. or higher, the magnetoresistive change rate of the multilayer film decreases. Although it is difficult to determine the temperature at which the rate of change in magnetoresistance decreases,
The rate of change in magnetoresistance of the multilayer film after heat treatment at 305 ° C. greatly differs depending on the multilayer film. Table 2 shows the relationship between the magnetoresistance change rate of the multilayer film after the heat treatment at 305 ° C. and the buffer layer material.

[0011]

[Table 2]

As shown in Table 2, when the group V elements of the periodic table, V, Nb, and Ta are used as the buffer layer material, the amount of decrease in the magnetoresistance change rate is small. On the other hand, when Ti, Zr, and Hf, which are group IVa elements in the periodic table, are used as the material of the buffer layer, the magnetoresistance change rate is significantly reduced.

As described above, the multilayer film using V, Nb, and Ta, which are elements of the Va group of the periodic table, has a problem in magnetic characteristics. On the other hand, the multilayer film using Ti, Zr, and Hf which are group IVa elements has excellent magnetic characteristics, but has a problem in heat resistance. It is an object of the present invention to provide a solution to the problem in the high magnetoresistive effect multilayer film for the magnetoresistive effect head described above.

[0014]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies as to a magnetoresistive effect element using a multilayer magnetic film in which magnetic layers having various materials and film thicknesses and non-magnetic layers are laminated. Between the multilayer film and the substrate, in the periodic table
The inventors have found that the magnetic characteristics and heat resistance of the multilayer magnetoresistive effect film can be improved by forming a buffer layer made of an alloy of a group IVa element and a group Va element, and have completed the present invention.

That is, a multilayer film including two magnetic layers separated by a non-magnetic layer and an antiferromagnetic layer for applying an exchange bias magnetic field to one of the two magnetic layers is formed. In the multilayer magnetoresistive effect film formed on the substrate, a buffer layer made of an alloy of an IVa group element and a Va group element in the periodic table is formed between the multilayer film and the substrate, whereby The magnetic characteristics and heat resistance can be improved.

The above alloys are, for example, V-Ti, V-Z.
r, V-Hf, Nb-Ti, Nb-Zr, Nb-Hf,
Although it is a binary alloy such as Ta-Ti, Ta-Zr, Ta-Hf alloy, three or more kinds of IVa group element and Va group element may be combined. The composition of the IVa group element with respect to the Va group element of the alloy forming the buffer layer is 20 to 80.
It is preferably at%. In addition, IVa group element and Va
Even if the element of the other group is contained in addition to the group element, the amount thereof does not matter as long as the heat resistance and soft magnetic characteristics are not deteriorated.

The above-mentioned 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.

[0018]

As described above, by forming the buffer layer made of an alloy of the IVa group element and the Va group element in the periodic table between the multilayer film and the substrate, the magnetic characteristics of the multilayer magnetoresistive film are obtained. And heat resistance can be improved.

[0019]

EXAMPLES Va in the periodic table as a buffer layer material
The multilayer film using the group elements V, Nb, and Ta has excellent heat resistance, but the magnetic layer has a high coercive force. Therefore, V, Nb,
Ti, Zr, and Hf are added to the buffer layer made of Ta,
We tried to reduce the coercive force. The structure of the multilayer film is the same as that of the conventional example shown in FIG. 1 except for the buffer layer material. That is,
The substrate 11 is made of Si (100) single crystal, and the magnetic layer 13
And 15 have a thickness of 5 nm of Ni-16 at% Fe-18.
At% Co alloy was used. The nonmagnetic layer 14 has a thickness of 2.5.
nm Cu is used, and the antiferromagnetic layer 16 has a thickness F of 5 nm.
An e-40 at% Mn alloy was used. The protective layer 17 was made of the same material as the buffer layer 12 and had a thickness of 5 nm.
The buffer layer 12 has a thickness of 5 nm.

Example 1 First, Ti, Zr, and Hf were added to the buffer layer made of V. Magnetic layer 1 in FIG.
FIG. 5 shows the relationship between the coercive force in the direction of easy magnetization of 3 and the added amounts of Ti, Zr, and Hf. In the figure, ◯ indicates the case where Ti is added, □ indicates the case where Zr is added, and Δ indicates the case where Hf is added. As shown in the figure, the coercive force decreases as the amount of Ti, Zr, and Hf added increases. When 20 at% or more of Ti, Zr, and Hf is added, the coercive force is 2.5 O
e or less.

The multilayer film was heat-treated. 305 ° C
Change rate of multi-layered film after heat treatment at room temperature and Ti, Zr,
The relationship with the amount of Hf added is shown in FIG. As shown in the figure, T
The heat resistance decreases as the amount of i, Zr, and Hf added increases. In order for the magnetoresistance change rate after heat treatment to be 1.5% or more, the addition amount of Ti, Zr, and Hf should be 80 at%.
It must be: As described above, in order to obtain excellent magnetic properties and heat resistance at the same time, T with respect to V is
It is necessary to add i, Zr, and Hf in an amount of 20 to 80 at%.

Example 2 Next, Ti, Zr, and Hf were added to the buffer layer made of Nb. FIG. 7 shows the relationship between the coercive force of the magnetic layer 13 in FIG. 1 in the easy magnetization direction and the amounts of addition of Ti, Zr, and Hf. In the figure, ◯ indicates the case where Ti is added, □ indicates the case where Zr is added, and Δ indicates the case where Hf is added. As with V, Ti, Zr,
The coercive force decreases as the amount of Hf added increases. About 20
When Ti, Zr, and Hf of at% or more are added, the coercive force becomes 2.5 Oe or less.

FIG. 8 shows the relationship between the magnetoresistance change rate of the multilayer film after the heat treatment at 305 ° C. and the added amounts of Ti, Zr and Hf. As shown in the figure, in order for the magnetoresistance change rate after heat treatment to be 1.5% or more, the amount of addition of Ti, Zr, and Hf must be about 80 at% or less.

Example 3 Further, Ti, Zr, and Hf were added to the buffer layer made of Ta. FIG. 9 shows the relationship between the coercive force of the magnetic layer 13 in FIG. 1 in the easy magnetization direction and the amounts of addition of Ti, Zr, and Hf. In the figure, ◯ indicates the case where Ti is added, □ indicates the case where Zr is added, and Δ indicates the case where Hf is added. As with V, Ti, Z
The coercive force decreases as the added amounts of r and Hf increase. When about 20 at% or more of Ti, Zr, and Hf are added, the coercive force becomes 2.5 Oe or less.

FIG. 10 shows the relationship between the magnetoresistance change rate of the multilayer film after the heat treatment at 305 ° C. and the addition amounts of Ti, Zr and Hf. As shown in the figure, in order for the magnetoresistance change rate after heat treatment to be 1.5% or more, the amount of addition of Ti, Zr, and Hf must be about 80 at% or less. As described above, the characteristics of the multilayer film are substantially determined by the group of the periodic table of the material of the buffer layer. Therefore, the effects of adding Ti, Zr, and Hf to V, Nb, and Ta are almost the same. In order to obtain a multilayer film having excellent magnetic properties and heat resistance, a buffer layer composed of V, Nb, and Ta should have a thickness of 20 to 20.
It is preferable to add 80 at% of Ti, Zr, and Hf.

When X-ray diffraction was carried out on the multilayer film of each of the above-mentioned examples, the multilayer film showed a strong (111) orientation.
In particular, the multilayer film having excellent soft magnetic properties showed a strong (111) orientation. Although the buffer layer of the binary alloy has been described in the above-mentioned embodiments, a ternary or higher alloy may be used as long as the composition of the IVa group element with respect to the Va group element is 20 to 80%.
In particular, Zr and Hf are difficult to separate. Therefore, by using a sputtering target in which Zr and Hf are mixed, the target can be obtained at low cost and the characteristics of the multilayer film are not affected. In addition, IVa group element and V
Even if the element of the other group is contained in addition to the element of the group a, the amount thereof does not matter as long as the heat resistance and soft magnetic characteristics are not deteriorated.

Further, in the above embodiment, Ni is used as the magnetic layer.
Although the -Fe-Co alloy was used, similar results 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.

In the above embodiment, the nonmagnetic layer is
Although Cu is used, similar results can be obtained by using Au or Ag having a low electric resistivity. 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. Further, in the above-mentioned embodiment, as the antiferromagnetic layer, Fe-
Although the Mn-based alloy is used, other antiferromagnetic materials can also be used. As the antiferromagnetic material, Cr-Mn, Pt-
Mn, Ir-Mn, Au-Mn, Ni-Mn based alloys and the like are preferable.

Example 4 A magnetoresistive effect element was formed using the multilayer film of the present invention. In this example, a 5 nm thick Nb-50 at% Hf alloy was used as the buffer layer 12 in FIG. The magnetic layers 13 and 15 have a thickness of 5n.
m Ni-16 at% Fe-18 at% Co alloy was used. Cu having a thickness of 2 nm was used for the non-magnetic layer 14. The antiferromagnetic layer 16 has a thickness of 5 nm of Fe-40 at% Mn.
An alloy was used. The protective layer 17 has a thickness of 5 nm of N.
A b-50 at% Hf alloy was used.

FIG. 11 shows the structure of the magnetoresistive effect element.
The magnetoresistive effect element has a structure in which a multilayer magnetoresistive effect film 41 and an electrode 42 are sandwiched between shield layers 43 and 44. 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 an applied magnetic field of about 1.6 kA / m (20 Oe). Showed a magnetoresistance change rate of about 3%. The reproduction output of the magnetoresistive effect element of the present invention is Ni-F.
e 2.8 times that of the magnetoresistive element using the single-layer film. In this embodiment, Nb is used as the buffer layer material.
Although a -50 at% Hf alloy was used, all the buffer layer materials of the present invention described in Examples 1 to 3 can be used as a multilayer buffer layer for a magnetoresistive effect element.

[Embodiment 5] A magnetic head was manufactured using the magnetoresistive effect element described in Embodiment 4. The structure of the magnetic head is shown below. FIG. 12 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 between the shield layers 52 and 53 functions as a reproducing head, and the lower magnetic pole 55 and the upper magnetic pole 56 sandwiching the coil 54 function as a recording head. Also, the electrode 58
As the material, a material having a multilayer structure of Cr / Cu / Cr was used.

The manufacturing method of this head will be described below. Al
_A sintered body containing 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 have a thickness of 1.0 μm, the lower magnetic pole 55 and the upper portion have a thickness of 3.0 μm, and the gap material between the layers is formed by sputtering.
1 ₂ O ₃ was used. The film thickness of the gap layer is 0.2 μm between the shield layer and the magnetoresistive effect element, and 0.
It was 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 .
Cu having a film thickness of 3 μm was used for the coil 54.

The magnetic head having the structure described above was incorporated in the magnetic recording / reproducing apparatus shown in FIG. 13A is a plan view of the magnetic recording / reproducing apparatus, and FIG. 13B is a sectional view taken along line AA. The disk-shaped magnetic recording medium 81 is rotationally driven by the drive unit 82. The magnetic head 83 has a drive unit 84.
A track on the magnetic recording medium 81 can be selected by being rotationally driven by. The recording / reproducing signal from the magnetic head 83 is processed by the recording / reproducing signal processing system 85.

When recording / reproducing was performed with this magnetic recording / reproducing apparatus, a reproducing output that was 2.8 times higher than that of a magnetic head using a 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. Further, the magnetoresistive effect element of the present invention can be used in a magnetic field detector other than the magnetic head.

[0035]

As described above, in the multilayer film in which the exchange bias magnetic field from the antiferromagnetic layer is applied to a part of the magnetic layer,
By forming a buffer layer made of an alloy of group IVa and group Va of the periodic table on a substrate, a multilayer film having excellent soft magnetic characteristics and high heat resistance can be obtained. 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.

[Brief description of drawings]

FIG. 1 is a sectional view showing the structure of a multilayer magnetoresistive effect film.

FIG. 2 is a magnetoresistive effect curve of a multilayer film having V, Nb, and Ta buffer layers.

FIG. 3 is a magnetoresistive effect curve of a multilayer film using Ti, Zr, and Hf buffer layers.

FIG. 4 is a graph showing the relationship between the heat treatment temperature of a multilayer film and the magnetoresistance change rate.

FIG. 5 is a graph showing reduction in coercive force when Ti, Zr, and Hf are added to V.

FIG. 6 is a graph showing deterioration of heat resistance when Ti, Zr, and Hf are added to V.

FIG. 7 is a graph showing reduction in coercive force when Ti, Zr, and Hf are added to Nb.

FIG. 8 is a graph showing deterioration of heat resistance when Ti, Zr, and Hf are added to Nb.

FIG. 9 is a graph showing reduction in coercive force when Ti, Zr, and Hf are added to Ta.

FIG. 10 is a graph showing deterioration of heat resistance when Ti, Zr, and Hf are added to Ta.

FIG. 11 is a perspective view showing the structure of a magnetoresistive effect element using a multilayer magnetoresistive effect film.

FIG. 12 is a perspective view showing the structure of a magnetic head.

FIG. 13 is a schematic diagram of a magnetic recording / reproducing apparatus.

[Explanation of reference numerals] 11 ... Substrate 12 ... Buffer layer 13, 15 ... Magnetic layer 14 ... Nonmagnetic layer 16 ... Antiferromagnetic layer 17 ... Protective layer 41 ... Multilayer magnetoresistive effect film 42 ... Electrodes 43, 44 ... Shield Layer 51 ... Multilayer magnetoresistive film 52, 53 ... Shield layer 54 ... Coil 55 ... Lower magnetic pole 56 ... Upper magnetic pole 57 ... Base 58 ... Electrode 81 ... Magnetic recording medium 82 ... Drive section 83 ... Magnetic head 84 ... Drive section 85 ... Recording / reproducing signal processing system

Claims (10)

[Claims] 1. A two-layer magnetic layer separated by a non-magnetic layer,
A multilayer magnetoresistive effect film in which a multilayer film including an antiferromagnetic layer for applying an exchange bias magnetic field to one of the two magnetic layers is formed on a substrate, wherein the multilayer film and the substrate are A multilayer magnetoresistive effect film, characterized in that a buffer layer made of an alloy of an IVa group element and a Va group element in the periodic table is formed between the two. 2. The alloy forming the buffer layer is Va
The multilayer magnetoresistive effect film according to claim 1, wherein the ratio of the group IVa element to the group element is 20 to 80 at%. 3. The buffer layer is V-Ti, V-Z
The multilayer magnetoresistive effect film according to claim 1 or 2, which is made of an alloy selected from the group consisting of r and V-Hf. 4. The buffer layer is Nb-Ti, Nb-
The multilayer magnetoresistive effect film according to claim 1 or 2, which is made of an alloy selected from the group of Zr and Nb-Hf. 5. The buffer layer is made of Ta-Ti, Ta-
3. The multilayer magnetoresistive effect film according to claim 1, which is made of an alloy selected from the group of Zr and Ta-Hf. 6. The magnetic layer has a face-centered cubic structure,
11) The multilayer magnetoresistive effect film according to any one of claims 1 to 5, which is oriented. 7. A magnetoresistive effect element comprising: the multilayer magnetoresistive effect film according to claim 1; and a pair of electrodes for energizing the multilayer magnetoresistive effect film. 8. A magnetic head comprising the magnetoresistive effect element according to claim 7. 9. A magnetic head comprising the magnetoresistive effect element according to claim 7, a pair of magnetic poles, and a coil interlinking the magnetic poles. 10. A magnetic recording medium, the magnetic head according to claim 8 or 9, drive means for relatively driving the magnetic recording medium and the magnetic head, and a recording / reproducing signal connected to the magnetic head. A magnetic recording / reproducing apparatus including a processing system.