JP3021785B2 - Magnetoresistive material and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetoresistive material for reading signals from a magnetic medium and a method of manufacturing the same.

[0002]

BACKGROUND ART magnetoresistive sensor using a magnetoresistance element conventionally - (hereinafter MR sensor - called), has been advanced development of magnetoresistive head (hereinafter referred to as MR head), mainly Ni _0.8 to magnetic Permalloy of Fe _0.2 is used. However, in the case of this material, the resistance change rate (hereinafter, ΔR / R
) Is about 2.5%, and a higher ΔR / R is required to obtain a more sensitive magnetoresistive element. One of them is a Ni-Co alloy containing 60 to 80 atomic% of Ni. Although there is a film, the value of ΔR / R was still about 5.8% at the maximum.

In recent years, it has been discovered that a large magnetoresistance effect occurs in [Fe / Cr] artificial lattice films (Physical Review Letter V. Biol 61, P2472, 1988).
"Physical Review Letter Vol.61, p2472, 1988")
However, in the case of this material, a large ΔR / R cannot be obtained unless a large magnetic field of more than tens of kOe is applied, and there is a problem in practicality.

In addition, Ni _0.8 Fe _0.2
(30 報告) / Cu (50Å) / Co (30Å) / Cu (50Å) x 15 layers of artificial lattice film showed a resistance change of ΔR / R of about 10% (3 kOe magnetic field applied). . (Preliminary report of the Japan Society of Applied Physics, Fall 1990) However, there are problems that expensive multi-element ultra-high vacuum deposition equipment is required to produce films, and large ΔR / R cannot be obtained unless a large magnetic field of about 3 kOe is applied. there were.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and can be formed by a multi-source sputtering apparatus requiring substantially only two targets, and has a practically low magnetic field. This enables a magnetoresistive material exhibiting a relatively large ΔR / R.

[0006]

In order to solve the above-mentioned problems, a magnetoresistive element according to the present invention has the following configuration. That is, using a sputtering apparatus, a metal magnetic thin film layer made of Ni-Co containing Ni of 50 atomic% or more and having a thickness of 10 to 100 mm and a thickness of 10 to 25 mm
磁 気 is a magnetoresistive material having a structure in which a metal nonmagnetic thin film layer made of Cu is laminated.

[0007]

When the metal non-magnetic thin film layer has a certain thickness, an antiferromagnetic interaction acts between two adjacent metal magnetic thin film layers separated by the metal non-magnetic thin film layer. It is considered that the spin arrangement of the magnetic thin film layer is antiparallel to each other, and the spin scattering of conduction electrons is maximal, indicating a large magnetoresistance. When the applied magnetic field is further increased, the spin arrangement of the magnetic thin film layer becomes parallel, so that spin scattering of conduction electrons is reduced and the magnetoresistance is reduced. In this way, a large Δ
It is considered that R / R can be obtained, but if there is no metal non-magnetic thin film layer, the magnetic thin film layers are ferromagnetically coupled in parallel and an antiparallel state cannot be realized, so that a large magnetoresistance effect cannot be obtained. If the thickness of the metal non-magnetic thin film layer is too large, the above interaction vibrates like RKKY and attenuates, so that a large magnetoresistance effect cannot be obtained.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The magnetic thin film layer is a film made of Ni--Co having a thickness of 10 to 100.degree. If the content of Ni is less than this, there arises a problem that it is difficult to obtain soft magnetism. A typical material that satisfies these conditions is Ni _0.8 Co _0.2
It is. Further, Nb, Mo, Cr, W, Ru, etc. may be added in order to further improve the soft magnetism and the abrasion resistance and corrosion resistance.
When the thickness of these magnetic thin film layers is less than 10 mm, there is a problem of a decrease in magnetization at room temperature due to a decrease in Curie temperature, and in practice, the total thickness of a magnetoresistive element is hundreds of mm. In order to utilize the lamination effect as described above, each magnetic thin film layer must be at least 100 ° or less. Therefore, the thickness of these magnetic thin film layers is desirably 10 to 100 °.

The metal thin film interposed between these magnetic thin films must have a small reaction at the interface with the Ni—Co-based magnetic thin film and be non-magnetic, and Cu is suitable. The thickness of this Cu layer is optimally about 20 mm, and when it is less than 10 mm, two adjacent magnetic thin film layers are magnetically coupled via the Cu layer (FIG. 1), and the spin between the magnetic layers is antiparallel. It becomes difficult to realize such a state.

Although the reason is not obvious, the value of ΔR / R is Cu
When RKKY-like vibration is exhibited depending on the thickness of the layer and the maximum first peak is used, it is more preferable that the thickness of the Cu layer be 25 ° or less.

Hereinafter, the effects of the present invention will be described with reference to specific examples. (Example 1) Using a multi-source RF sputtering apparatus, Cu, Ni _0.8 Co _0.2 was used as a target, and the inside of the sputtering apparatus was 2 × 10 ^−7.
After exhausting to Torr, Ar gas was introduced to 8 × 10 ^-3 Torr,
Magnetoresistive elements having the following structures were sequentially formed on a glass substrate by sputtering.

[NiCo (30) / Cu (0-50)] (() indicates thickness ()
The film thickness was controlled by a sputtering time and a shutter to produce a film having a total thickness of about 0.2 μm.

The characteristics of the obtained magnetoresistive material are shown in FIG. Note that ΔR / R was measured with an applied magnetic field of 300 Oe.

As apparent from FIG. 2, it is found that the maximum value of ΔR / R exists in the vicinity of 20 ° in the Cu layer, and that the maximum value decreases with an increase in the thickness of the Cu layer when the Cu layer is more than 20 °. Therefore, in order to obtain the maximum ΔR / R, the optimum value is about 20 ° for the Cu layer.

(Embodiment 2) Using an RF sputtering apparatus,
A film in which the thickness of the Cu layer was fixed and the thickness of the magnetic layer was changed using Cu, Ni _0.8 Co _0.2 as a target was produced in the same manner as in Example 1 by sputtering.

The properties of the obtained film are shown in Table 1.

[0017]

[Table 1]

For reference, the same structure as that of No.
The ΔR / R of the sample using Co instead of _0.8 Co _0.2 was 5%.

[0019]

As described above, according to the present invention, it is possible to fabricate a conventional sputter apparatus by using only two targets without using an expensive ultra-high vacuum deposition apparatus. Further, it enables a magnetoresistive element exhibiting a large magnetoresistance effect with a practically applied magnetic field, and is suitable for application to a high-sensitivity MR head, an MR sensor, and the like.

[Brief description of the drawings]

FIG. 1 is a view showing the arrangement direction of spins in each magnetic layer of a magnetoresistive material of the present invention when an applied magnetic field is weak.

FIG. 2 is a diagram showing the dependence of the MR change rate of a magnetoresistive material in Example 1 on the thickness of a Cu layer.

[Explanation of symbols]

 1, 1 'metal magnetic thin film layer 2 metal nonmagnetic thin film layer

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 43/08 G11B 5/39 H01F 10/16 H01F 41/18 H01L 43/12

Claims (5)

(57) [Claims] (1) a thickness of 10 to 100 mm and containing at least 50 atomic% of Ni;
Metal magnetic thin film layer composed of Ni-Co and Cu with a thickness of 10 to 25 mm
A magnetoresistive material having a structure in which metal nonmagnetic thin film layers made of metal are alternately stacked. (2) Ni-Co containing 50 atomic% or more of Ni,
A first magnetic thin film layer having a thickness of 10 to 100 mm and Ni
A second magnetic thin film made of Ni-Co containing 10 to 100 mm thick
The film layer is made of non-magnetic metal with Cu as the main component and thickness of 10 ~ 25mm
A magnetoresistive material that is alternately stacked with thin film layers interposed. 3. A magnetoresistive material according to claim 1, wherein
A method for producing a magnetoresistive material, comprising: forming a metal magnetic thin film layer and a metal non-magnetic thin film layer sequentially using a multi-source sputtering apparatus. 4. Use of the magnetoresistance effect material according to claim 1.
Had a magnetoresistive sensor. 5. Use of the magnetoresistive material according to claim 1.
Had a magnetoresistive head.