JPH02202005A - Soft magnetic thin film - Google Patents

Abstract

PURPOSE:To obtain a thin film having sufficiently low coercive force by a method wherein an artificial lattice film is formed by laminating a magnetic transition metal layer and a non-magnetic metal layer mainly composed of Zr and/or Nb alternately. CONSTITUTION:A magnetic transition metal layer and a non-magnetic metal layer of layer thickness 1 to 6, mainly composed of Zr and/or Nb, are laminated alternately. At this point, pure Co, a Co-Fe alloy, a Co-Ni alloy, a Co-Fe-Ni alloy and the like are used as the material for the magnetic transition metal layer, and its layer thickness is set at 2 to 40 atomic layers. Pure Zr, pure Nb or an Nb-Zr alloy is used as the material for the above-mentioned non- magnetic metal layer. It is desirable that Z contains 70 atomic % or more, and its layer thickness is to be 1/4 to 1/20 of the magnetic transition metal layer. As a result, very low coercive force can be accomplished while high saturated magnetic flux density is being maintained, and a magnetic head suitable for high density recording can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a soft magnetic thin film, and more particularly to a soft magnetic thin film used as a core material of a magnetic head that exhibits performance suitable for high-density recording.

[Summary of the invention]

The present invention provides a soft magnetic thin film used as a core material of a magnetic head, in which a magnetic transition metal layer and a non-magnetic metal layer mainly composed of Zr and/or Nb and having a thickness of I to 6 atomic layers are alternately arranged. By laminating them, it is possible to reduce the coercive force.

[Conventional technology]

For example, in magnetic recording and reproducing devices such as audio tape recorders and VTRs (video tape recorders),
Recording signals are becoming more dense and of higher quality, and so-called metal tapes, which use ferromagnetic metal powder such as iron as magnetic powder, and ferromagnetic metal materials are deposited directly onto base films using vacuum thin film formation technology. So-called vapor-deposited tapes and the like have been put into practical use.

By the way, in order to make good use of the characteristics of a magnetic recording medium having such a high coercive force for good recording and reproduction, it is necessary to
- It is necessary for the core material of the magnetic head to have high saturation magnetic flux density and low coercive force.

Various materials have been developed to date as soft magnetic materials that meet these demands, and these are usually used in bulk or thin film form.

A Co-based amorphous magnetic alloy thin film is one example. This alloy thin film has a coercive force that is more than an order of magnitude smaller than a crystalline soft magnetic thin film such as Sendust, has high magnetic permeability, has excellent frequency characteristics due to its large specific resistance, and has extremely high corrosion and wear resistance. The relationship between composition and soft magnetism is not strict, so there is a large degree of freedom in design. It is easy to induce -axis anisotropy, so magnetic permeability in the direction of the difficult-to-magnetize axis can be effectively used. have. For example, JP-A-59-88801 discloses a Co-Zr-Nb amorphous alloy thin film, Journal of the Japan Society of Applied Magnetics, Vol. 12, 29.
Co-Nb-Ta on pages 9-304 (1988)
-Zr-based composition f: A controlled nitrided amorphous alloy film has been reported.

[Problem to be solved by the invention]

However, the thin film-like soft magnetic materials that have been reported so far generally have higher coercive force than bulk materials, and there is still room for improvement in magnetic properties.

Therefore, an object of the present invention is to provide a soft magnetic thin film having a sufficiently low coercive force even in the form of a thin film.

[Means for Solving the Problems] As a result of repeated studies to achieve the above-mentioned object, the present inventors have found that a certain type of magnetic transition metal layer and Zr and/or N
The present inventors have discovered that a sufficiently low coercive force can be achieved by alternately laminating nonmagnetic metal layers mainly composed of B to form an artificial lattice film, and have completed the present invention.

That is, the soft magnetic thin film according to the present invention is characterized in that magnetic transition metal layers and nonmagnetic metal layers mainly composed of Zr and/or Nb and having a thickness of 1 to 6 atomic layers are laminated alternately. It is.

The material for the magnetic transition metal layer is pure Co.

Co-Fe alloy, Co-Ni alloy, Go-Fe-N
When using 0 alloys such as i-based alloys, Fe, Ni, or Fe! : The total Ni content is preferably 80 atomic % at most from the viewpoint of maintaining good soft magnetic properties, and the layer thickness of the magnetic transition metal layer is 2 to 40 atomic layers. This layer thickness is equal to 5 to 100 people, assuming that the interatomic distance of Co or the average interatomic distance of the above alloy is 2.5 people.

In order to improve corrosion resistance and wear resistance, the magnetic transition metal layer further contains Ti, V, Ta, etc. up to 5 atomic %.
Cr, Mo, W, B, C, Si.

Aj! , Ge, and Ga may be added.

The material for one of the nonmagnetic metal layers is pure Zr.

Pure Nb or Nb-Zr alloy is used.

The composition of the Nb-Zr alloy is not particularly limited, but in order to achieve an extremely low coercive force of 0.10e or less, it is desirable to contain 70 atomic percent or more of Zr.
Further, the non-magnetic metal layer may be doped with Hf or the like, and the thickness of the non-magnetic metal layer is set to 1 to 6 layers. This layer thickness is equal to 2.5 to 15 atoms when the average interatomic distance of Nb, Zr or Nb-Zr alloy is 2.5 atoms, and a more preferable range is 2 to 3 atomic layers (5 to 7.5 atoms). ) is,
However, the thickness of this nonmagnetic metal layer is 1/2 to 1/20 that of the magnetic transition metal layer. Outside this range, the coercive force tends to increase.

In order to create the soft magnetic thin film of the present invention, sputtering is usually performed, and high-frequency magnetron irradiation is performed on a suitable substrate.
Sputtering, DC sputtering, ion beam
The magnetic transition metal layers and nonmagnetic metal layers are alternately laminated by sputtering or the like. General sputtering conditions can be applied. The number of stacked magnetic transition metal layers and nonmagnetic metal layers and the total thickness of the soft magnetic thin film are not particularly limited, and may be appropriately selected according to desired characteristics. In addition, when using additive elements to improve corrosion resistance or wear resistance, an alloy of the additive element and the material constituting the magnetic transition metal layer is used as a target, or the material constituting the magnetic transition metal layer is Sputtering can be performed by placing a chip of the additive element on a target of the material to be used.

As is clear from the above description, the soft magnetic thin film formed in the present invention has an artificial lattice structure. Ideally, the interface between the magnetic transition metal layer and the non-magnetic metal layer is formed flat, but even though the interface is slightly disturbed, the composition as a whole maintains a constant period and changes. It may have a so-called composition modulation structure.

Further, nitrogen may be contained in either or both of the magnetic transition metal layer and the nonmagnetic metal layer. In this case, nitrogen is mixed into the atmospheric gas at a rate of 1% or less during sputtering.

Furthermore, prior to forming the soft magnetic thin film, a suitable base film may be provided on the substrate.

[Effect]

In the present invention, Co is added with Nb, Zr, etc.
% Amorphous alloy is replaced with a soft magnetic thin film in which magnetic transition metal layers mainly composed of Go and nonmagnetic metal layers mainly composed of Zr and/or Nb are alternately laminated. This makes it possible to further reduce coercive force without reducing saturation magnetization.

〔Example〕

Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

Example 1 This example is an example of a Co/Zr based soft magnetic thin film in which the Co layer is a magnetic transition metal layer and the Zr layer is a nonmagnetic metal layer.

The above-mentioned Co/Zr-based soft magnetic thin film was created as follows.

First, 100
Co and Zr targets each having a diameter of mm were placed, and a water-cooled glass substrate was placed on a rotating base that was placed facing these targets. In this state, the gas pressure is 5 xlO-”
In an argon atmosphere of Torr, sputtering speed 1~
Direct current sputtering was performed by 10 people, and the 00 layer and the Zr layer were alternately stacked at varying layer thickness ratios in the range of 172 to 8/1 until the total thickness was 1 μm.
A Zr-based soft magnetic thin film was formed.

Figure 1 shows the results of measuring the coercive force of a Co/Zr-based soft magnetic thin film with a thickness ratio of 271 to 8/1 between the Co layer and the Zr layer, in which the vertical axis represents the coercive force ( Oe), and the horizontal axis represents the layer thickness (in people) of the 00 layer, respectively. Also, line a1
The case where the layer thickness ratio of the Co layer and the Zr layer is 271.

Line a2 is 3/1, line a is 4/1, line a4
indicates the case of 6/1, and line a indicates the case of 8/1.According to this figure, in most cases, it shows a change that takes a minimum value depending on the layer thickness of the Co layer, The thickness of the Zr layer at the minimum value is 5 people in all cases. That is, it can be seen that these soft magnetic laminated films exhibit the lowest coercive force when the thickness of the Zr layer is selected to be two atomic layers. In particular, when 10 people are in the Co layer and 5 people are in the Zr layer, as is clear from the magnetization curve shown in Figure 2,
The coercive force was an extremely excellent value of 0.080e.

Figure 3 shows that the thickness ratio of the Co layer and Zr layer is 1/4 to 8/1.
In Figure 0, which shows the results of measuring the saturation magnetization of the C o / Z r -based soft magnetic laminated film, the vertical axis is the saturation magnetization (G
auss) r The horizontal axis represents JiyL (person) of the Co layer, respectively. Also line 1. is the layer thickness specific force of Co layer and Zr layer 1/
If 4(7), line bt If 1/2(7), t/A
b 3 In the case of C 1/1, the line b4 is 2/1, the line S is 4/1, the line S is 6/1, the line S is 8
/1 respectively. When the thickness ratio of the Co layer and the Zr layer is 1/4 to 1/1 (line b+""bz), the saturation magnetization value is low in both cases, and the value depends on the layer thickness of both layers. and change. On the other hand, the layer thickness ratio is 271 to 8/1.
It can be seen that in all cases (lines b4 to by), the value of saturation magnetization is high, and the value is almost constant regardless of the layer thickness of each layer as long as the layer thickness ratio is constant.

Example 2 In this example, the Co-Fe alloy layer is a magnetic transition metal layer,
This is an example of a Co-Fe/Zr-based soft magnetic thin film in which the Zr layer is a nonmagnetic metal layer.

The above-mentioned Co-Fe/Zr-based soft magnetic thin film was created in the same manner as in Example 1, using a Co--Fe alloy target instead of the Co target in Example 1. Here, the Co--Fe alloy target is Cos. Fe,. ,Cow.

Fes. ,Cow. Fey. (However, all numbers represent compositions in atomic %.) Three types of compositions were used. In this way, since the layer thickness ratio of the Co-Fe alloy layer and the Zr layer is varied in the range of 271 to 8/1, the total thickness is 1.
By stacking layers alternately until the thickness of various Co
/Zr-based soft magnetic thin film was formed.

FIG. 4 shows the results of measuring the coercive force of these Co--Fe/Zr-based soft magnetic thin films. In the figure, the vertical axis represents the coercive force (Oe), the horizontal axis represents the layer thickness (in) of the Co-Fe alloy layer, and the plots of circles (lines C1""C4) represent Go-
This represents the case where the composition of the Fe alloy layer is C05oFe2°, and the line C1 represents the case where the layer thickness ratio of the Co-Fe alloy layer and ZrJi is 2/
1, the line c represents the case of 4/1, the line C2 represents the case of 6/1, and the line C4 represents the case of 8/1.The square mark plot (lines C2 to Ct) represents the Co-Fe alloy. The composition of the layer is C
represents the case where o5oFeso, and line C3 is Co-Fe
When the layer thickness ratio of the alloy layer and the Zr layer is 1/2, the line C1 is 4/
1, gland C1 represents the case of 6/1, respectively. Plot of triangle marks (line CL CJ indicates that the composition of the Co-Fe alloy layer is Co).

Fe? 0, ice represents the case where the layer thickness ratio of the Co--Fe alloy layer and the Zr layer is 2/1, and line C9 represents the case where the thickness ratio is 4/1.

Looking at this figure, all soft magnetic thin films show changes with a certain minimum value. The layer thickness (number of atomic layers) of the Zr layer when it takes a minimum value is when the composition of the Co-Fe alloy layer is Cow. Fe,
. If 5 people (2 atomic layers), C05oFeso
and 5 to 7.5 people (2
With some exceptions, most of these minimum values are distributed in the region of less than 0.50e, which indicates that the soft magnetic thin film is extremely suitable for practical use.

FIG. 5 shows the results of measuring the saturation magnetization layer of these Co--Fe/Zr-based soft magnetic thin films.

In the figure, the circle plot (line d+-d4) indicates that the composition of the Co--Fe alloy layer is Co. Fe,. represents the case where the line d
1 is when the layer thickness ratio of the Co-Fe alloy layer and Zr layer is 271, line d2 is 4/1, line d is 6/1, s#
t a 4 represents the case of 8/l. The square plots (lines d, ~ds) indicate that the composition of the Co-Fe alloy layer is Cos. Fes. , and the line d is C
When the layer thickness ratio between the o-Fe alloy layer and the Zr layer is 172, the line d
6 is 4/1, line d is 6/1, aS is 8/
1 case is shown respectively. Triangle plot (line d9.
d+o), the composition of the Co-Fe alloy layer is Co. Fet.

The line d represents the case where the thickness ratio of the Co--Fe alloy layer and the Zr layer is 271, and the line d1° represents the case where the thickness ratio is 4/1.

From this figure, the magnitude of saturation magnetization tends to increase as the layer thickness ratio with the Zr layer increases, regardless of the composition of the Co-Fe alloy layer, and its value increases as long as the layer thickness ratio is constant. It can be seen that it is almost constant regardless of the layer thickness of each individual layer.

Example 3 This example is an example of a Co/Nb based soft magnetic thin film in which the Co layer is a magnetic transition metal layer and the Nb layer is a nonmagnetic metal layer.

The above Co/Nb-based soft magnetic thin film uses a Nb target instead of the Zr target in Example 1,
It was prepared in the same manner as described in Example 1. The total thickness is 1 μm.

Here, FIG. 6A shows the magnetization curve when the Co layer has 15 layers and the Nb layer has 7.5 layers (3 atomic layers) (that is, layer thickness ratio 2/1). In the figure, the vertical axis direction represents the magnetic flux density (relative scale), and the horizontal axis direction represents the strength of the magnetic field.

It was found that the coercive force was extremely small at 0.40e.

Also, 10 people for the Co layer and 2.5 people for the Nb layer (1 atomic layer)
(i.e., layer thickness ratio 4/1), the magnetization curve is
Shown in Figure (B). This Co/Nb-based soft magnetic thin film achieved an extremely small coercive force of 0.250e.

Example 4 In this example, the 00 layer is a magnetic transition metal layer, and the Nb-Zr
This is an example of a Co/Nb-Zr based soft magnetic thin film in which the alloy layer is a non-magnetic metal layer.

The Co/Nb-Zr-based soft magnetic thin film is NbS instead of the Zr target in Example 1. Z
r@.

It was produced in the same manner as described in Example 1 using a Nb-Zr alloy target having a composition of Total thickness is 1
It is μm.

Here, 20 people were responsible for the Co layer, and 5 people (3
Figure 7 shows the magnetization curve in the case of atomic layer) (ie, layer thickness ratio of 4/1), and it was found that the coercive force was 0.750e, which was good.

〔Effect of the invention〕

As is clear from the above description, by applying the present invention, it is possible to achieve an extremely low coercive force while maintaining a high saturation magnetic flux density. In particular, if the composition and layer thickness of the magnetic transition metal layer and non-magnetic metal layer are appropriately selected, a coercive force of 0.10e or less, which could not be achieved with conventional Go-based amorphous alloy magnetic thin films, can be obtained, and high A magnetic head suitable for density recording can be provided.

[Brief explanation of the drawing]

FIG. 1 is a characteristic diagram showing the relationship between coercive force and layer thickness ratio of a Co/Zr based soft magnetic thin film. Figure 2 is a magnetization curve for an example of a Co/Z soft magnetic thin film. Figure 3 is a characteristic diagram showing the relationship between saturation magnetization and layer thickness ratio of the same Co/Zr soft magnetic thin film. .Figure 4 shows Co
FIG. 2 is a characteristic diagram showing the relationship between coercive force and layer thickness ratio of a −Fe/Zr-based soft magnetic thin film. Figure 5 shows Co-Fe/Zr
System soft magnetism 1111! FIG. 3 is a characteristic diagram showing the relationship between saturation magnetization and layer thickness ratio. Figure 6 <A) shows the magnetization curve for an example of a Co/Nb soft magnetic thin film, and Figure 6 (B) shows the same <C
o/Nb-based soft magnetic II! FIG. 7 shows magnetization curves for an example of a Co/Nb-Zr based soft magnetic thin film. Patent Applicant Sony Corporation Representative Patent Attorney Koike Mima Sakae Tamura - Masaru Sato Co11 No. 1 Atsushi (λn Figure 1 Figure 3 Figure 2 Procedural Litigation Manual (Spontaneous) 7. Contents of Amendment Heisei May 12, 1 year (1) On page 5, line 16 of the specification, “
1 to 6 people” Yoshi, Commissioner of the Japan Patent Office 1) Moon Takeshi
The description will be corrected to "1 to 6 atomic layers." ■, Indication of the case, 1999 Patent Application No. 2 2, Name of the invention, Soft magnetic thin film 3, Amended party No. 289 et seq. 4゜

Claims (1)

[Claims] A soft magnetic thin film characterized in that magnetic transition metal layers and nonmagnetic metal layers mainly composed of Zr and/or Nb and having a thickness of 1 to 6 atomic layers are laminated alternately.