JPH0620834A - Magnetic multilayer film - Google Patents

Abstract

PURPOSE:To obtain a magnetic multilayer film having coersive force abated by the films containing a ferromagnetic element in high saturated flux density. CONSTITUTION:Within This magnetic multilayer film wherein the films containing a ferromagnetic element and non-magnetic material at the facial intervals in matching relation with the facial intervals of the former films are alternately epitaxial grown to be laminated, the films containing the ferromagnetic film are Fe-N two element base films or Fe-Co-N three element base films while the non-magnetic material is at least one element selected out of NaO, GaAs, In0.2Ga0.8As furthermore the coersive force does not exceed 20Oe but the saturated flux density exceeds 2.0T.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic multilayer film, and more particularly to a magnetic multilayer film using a film containing a ferromagnetic element having a high saturation magnetic flux density as the magnetic film.

[0002]

_2. Description of the Related Art A conventional Fe ₁₆ N ₂ single crystal film has a coercive force of about 5
It was 0 Oe, and it was difficult to reduce the coercive force. The BH curve of the film containing Fe ₁₆ N ₂ is shown in Journal of Applied Physics 65 (11), 1
989, p. p. 4357-4361 (J. Appl. Phy
s. 65 (11) 1989). The in-plane coercive force is about 100 Oe from the in-plane B-H curve.
Further, it can be seen that the in-plane saturation magnetic field is 3.0 kOe or more. The cause is a large magnetocrystalline anisotropy energy,
This is due to the strain in the film. In order to reduce the contribution of the magnetocrystalline anisotropy energy, it has been proposed to change from a single crystal to an oriented polycrystalline film, to reduce the film thickness, and to release strain (Japanese Patent Laid-Open No. 62-221102). , JP-A-2-285609, JP-A-2-308504, and JP-A-3-1509). The saturation magnetic flux density of Fe ₁₆ N ₂ is high because Fe atoms and N atoms are regularly arranged and the volume is increased in a tetragonal system. When grown in a polycrystal, the order becomes low. Even when grown on a single crystal substrate, the order of Fe ₁₆ N ₂ decreases when the film thickness becomes 1 μm or more. When the film thickness is thin, dislocations and strains are introduced due to the misfit of the lattice for epitaxial growth along the periodic structure of the substrate, but the regularity is hardly reduced.

[0003]

In the above-mentioned prior art, since the coercive force is large, the magnetic permeability (about 5000) is low, and it is necessary to reduce the coercive force in order to use it as the core material of the magnetic head. Therefore, an object of the present invention is to provide a magnetic multilayer film in which the coercive force is reduced by a film containing a ferromagnetic element having a high saturation magnetic flux density, which solves the above problems.

[0004]

In order to achieve the above object, in the present invention, a film containing a ferromagnetic element and a non-magnetic material having a lattice constant similar to that of the material containing the ferromagnetic element are provided. And are alternately laminated (especially by epitaxial growth) to provide a magnetic multilayer film. In the magnetic multilayer film, the film containing a ferromagnetic element is a Fe—N binary film or a Fe—Co—N ternary film, and the nonmagnetic material is MgO, GaAs, In _0.2 Ga _0.8.
It is preferable to use at least one selected from As, and by stacking these, the crystal grain size can be made fine and stable growth can be achieved.

The magnetic multilayer film has a coercive force of 20 O.
e or less, particularly in the range of 1 to 20 Oe, the saturation magnetic flux density is 2.0 T or more, particularly in the range of 2.0 to 2.8, and the lamination period of the multilayer film is equal to or more than the lattice constant of the material forming each layer. Therefore, the total thickness of the film is preferably 100 Å or more and about 2 μ. When the Fe-N film or the Fe-Co-N alloy is used as the core material of the magnetic head, the corrosion resistance of the film becomes a problem.
Therefore, it is preferable to substitute Fe or Fe-Co with another element. Fe ₁₆ N ₂ body-centered tetragonal (bct), which has a structure in which only one direction of the bcc structure is extended, and is close to the atomic arrangement bcc structure. So bccF
As a result of substituting e and selecting an additive element having a stable bcc structure and investigating the corrosion resistance, it was found that the corrosion resistance of a film containing one or more of Cr, Mo, Nb, and V at 5 at% or more and up to about 20 at% Improved. When the above magnetic multilayer film is used as a main magnetic pole of a magnetic head, a magnetic head having a high magnetic field application characteristic and excellent recording / reproducing characteristics can be obtained, and a magnetic disk device can be obtained by using this magnetic head.

[0006]

Function: Fe-N binary alloy has a high saturation magnetic flux density F
There is an e ₁₆ N ₂ compound. The crystal magnetic anisotropy energy of this compound is 4.5 × 10 ⁵ erg / cc, which is almost equal to that of Fe, and has a soft magnetic property suitable for a core material of a magnetic head, etc., and is a magnetic film with a high saturation magnetic flux density. Is Fe ₁₆ N
_It is necessary to reduce the crystal grain size of the film containing ₂ . Further, since the electric resistance of Fe ₁₆ N ₂ is about 3 to 5 times that of Fe, it is necessary to further increase the resistance in order to reduce the eddy current loss.

In order to make the crystal grains smaller, it is possible to make them multi-layered. However, Fe ₁₆ N ₂ or Fe-N martensite and Fe-Co-N martensite are metastable phases, and when many defects are introduced during film growth,
Such metastable phases cannot grow. Therefore, in order to reduce the crystal grain size while keeping the structure of the metastable phase stable, a method of alternately laminating with a material having a lattice constant close to that of the metastable phase is effective. The material to be laminated with the Fe ₁₆ N ₂ is suitably a material having a lattice spacing or lattice constant close to that of Fe ₁₆ N _2, in the present invention MgO, GaAs and an In _0.2 Ga _0.8 at least one among As Stack one. These materials have high electrical resistance, and because never grow Fe ₁₆ N ₂ is inhibited, by reducing the thickness of the Fe ₁₆ N _2, Fe ₁₆ N
The magnetic anisotropy energy of ₂ can be reduced. F
Although e ₁₆ N ₂ is polycrystalline, it can grow as long as it is oriented, and a multilayer film in which crystal grains have an azimuth relationship can also be produced.

For example, Fe ₁₆ N ₂ is replaced with In _0.2 Ga _0.8 As
When epitaxially grown on a single crystal substrate, Fe ₁₆
The growth of N ₂ becomes unstable when the film thickness exceeds 0.1 μm.
Thus a film thickness growth of the Fe ₁₆ N ₂ is stable, Fe-N film to produce a Fe-N (containing the Fe ₁₆ N ₂₎ film of thick while keeping the grain size constant Considering the controllability of the particle size, the most effective method is to make the particles multi-layered. F
The decrease in the degree of order of e ₁₆ N ₂ (that is, the introduction of defects) corresponds to the decrease in Bs. However, by substituting a part of Fe with Co, the Bs of the entire film is in the case of Fe-N binary system. A coercive force of 20 Oe or less and a Bs of 2.7 T can be obtained.

The Fe-N binary material has a lower corrosion resistance than the permalloy or CoNiFe soft magnetic film. So F
It is effective to add the third element to the e-N alloy. At this time, the third element must be an element that does not adversely affect the epitaxial growth of Fe ₁₆ N ₂ . Fe ₁₆ N ₂
Since its crystal structure is bct, it is desirable that the additional element is a bcc stabilizing element that forms bcc when it forms a solid solution with Fe. In the present invention, as the bcc forming element of Fe, Cr, M
As a result of selecting o, Nb, and V, it was found that the corrosion resistance was significantly improved.

[0010]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. Example 1 First, the manufacturing conditions of the magnetic multilayer film will be described below. The substrate is In _0.2 Ga _0.8 As (001), GaAs (00
1) or MgO (001) single crystal, and the surface of the substrate is cleaned to remove the heterogeneous oxide. After the cleaning process of the substrate, to verify that broad patterns not by the substrate surface to observe the reflected electron diffraction pattern, a mixed gas of ammonia and nitrogen _{(NH 3: N 2 = 1} : 1~1:
10) Fe was vapor-deposited in the atmosphere. Growth rate is 0.1
0.01 Å / s, substrate temperature is 200 ° C. The Fe used for the vapor deposition source had a purity of 99.999%, and Co, C
The purity of r, Mo, Nb and V is 99.9% or more.

The total thickness of the multilayer film is 0.1 μm,
The intermediate layer of In _0.2 Ga _0.8 As, GaAs or MgO was vapor-deposited (about 1Å / s) in the same vapor deposition chamber, and the average thickness of the intermediate layer was 30 to 200Å. When the thickness of the intermediate layer is less than 30Å, the continuity of the film is deteriorated, and when it is more than 200Å, the saturation magnetic flux density is remarkably decreased. The film thickness of the Fe-N film was measured in the range of 100 to 1000Å. When the film thickness of the Fe-N film is less than 100 Å, the multilayer periodic structure is disturbed, so it is set to 100 Å or more.
When the Fe-N film thickness is 100 to 1000Å, the diffraction peak due to the period is observed in the small angle region of XRD (X-ray diffraction). Further, a diffraction peak showing the ordered structure of Fe ₁₆ N ₂ is observed in the produced Fe—N or Fe—Co—N film.

In the above film, the diffraction peaks are (002), (004), (220) and (1) in the XRD pattern.
03) has been observed. (002) of this peak
And (004) show that the c-axis of Fe ₁₆ N ₂ grows perpendicular to the substrate surface. This is equivalent to that the a-axis of Fe ₁₆ N ₂ is parallel to the substrate surface, and the length of the a-axis and the lattice constant of the above single crystal are almost the same, so that the growth of the single crystal at the interface is maintained. It can be said that it is epitaxially growing.

FIG. 1 shows the relationship between the coercive force (Hc) and the film thickness per layer of Bs and the Fe--N film. Hc of the multilayer film is Fe-
It decreases as the film thickness of the N film decreases. Hc is 20 Oe
It can be understood that the thickness of the Fe-N film should be 500 Å or less to realize the following. Hc value is In _0.2 Ga _0.8
As (-○-), GaAs (-●-), MgO (-□)
The reason why it increases in the order of −) is that it is related to lattice strain. On the other hand, the lattice constant difference between Fe ₁₆ N ₂ and each intermediate layer increases in the order of In _0.2 Ga _0.8 As, GaAs, and MgO, and the smaller the lattice strain, the smaller the coercive force of the multilayer film. This is because lattice strain traps the movement of the domain wall. In _0.2 Ga _0.8
The crystal grain size and F of the Fe-N film when As is used for the intermediate layer
The relationship of film thickness per e-N film layer is shown. It can be seen that as the film thickness (d) of the Fe—N film is made thinner, the crystal grain size of the film becomes smaller. When the thickness of the Fe-N film is 500 Å or less, the grain size is 300 Å or less, and at this time, it is clear from FIG. 1 that the coercive force is 20 Oe or less.

FIG. 3 shows the relationship between Bs of the Fe—N / In _0.2 Ga _0.8 As multilayer film and the film thickness per Fe—N film. Bs decreases as the film thickness of the Fe-N film decreases. However, in this thickness range, Bs is 2.0 T or more, and Fe
The magnetic flux density per -N film is higher than that of Fe. When the patterns of these multilayer films are observed by using XRD θ-2θ scanning, Fe ₁₆ N ₂ is shown to be a regular lattice.
₁₆ N ₂ (002) and (004) were observed. Also (2
The peaks of 20) and (103) were also measured. This is Fe
_{It is shown that 16} N ₂ is not a unidirectionally grown polycrystal film in which the c-axis is grown at an angle from the normal direction of the substrate surface.

Among these diffraction peaks, it is shown that the c-axis is inclined (103) (○) and (220).
The results of examining the intensity of the (●) peak are shown in FIG.
It is shown as a relative value when the strength is 1 when the film thickness of Fe-N is 1000 Å. These peak intensities become higher as the Fe-N film becomes thinner. This is Fe-N
As the film thickness decreases, the crystal grains become finer and at the same time Fe ₁₆ N
It shows that the direction of ₂ is shifted and growing. As a result, it is considered that the magnetic anisotropy of Fe ₁₆ N ₂ can be reduced and Hc can be reduced. FIG. 5 shows the Hk of these films. Similar to Hc, Hk also decreases as the thickness of the Fe-N film decreases. The dependence of the lattice strain on the Fe-N film thickness is shown by a dotted line. It can be seen that Hc and Hk of the Fe—N film become smaller as the crystal grain size becomes finer and the lattice strain increases.

Example 2 FIG. 6 shows Bs (− ◯ −) and Hc (− □ −) of a multilayer film when Fe—Co—N and In _0.2 Ga _0.8 As are multilayered. The Co concentration is 50 at%, and F is used as a vapor deposition source.
An Fe-Co alloy was used instead of e and vapor deposition was performed using an electron beam. Fe-Co compared to the Fe-N binary system in FIG.
It can be seen that the -N film has a higher Bs. Further, when the thickness of the magnetic film is 500 Å, in the case of the Fe-Co-N film,
T is high and Hc is 20 Oe or less. C
The addition of o increases the Bs because the Bs of (Fe, Co) ₁₆ N ₂ is higher than that of Fe ₁₆ N ₂ .

In FIG. 6, the corrosion resistance of the multilayer film produced with the film thickness of Fe--Co--N being 500Å is shown in FIG.
Bs when immersed in HCl 1 mol, 80 ° C., 1 hour)
FIG. 7 shows the change in Bs change of additive-free multilayer film is 80
% Or less. Cr (-○-), Mo (-●-), N
Corrosion resistance is improved by adding any one element of b (-Δ-) and V (-□-). In particular, the Bs change can be suppressed within 10% by setting the additive element concentration to 5 at% or more. The additive elements are Cr, Mo, N
The corrosion resistance is improved in the order of b and V.

Embodiment 3 FIG. 8 shows a cross section of a single magnetic head for a vertical disk. The multilayer magnetic film produced by the above method is used for the main pole 1, and the single crystal substrate is used for the substrate 2. NiFe is used for the yoke 3, a coil of 8 turns is used, and the whole is covered with the protective film 5. Co-Cr film (film thickness 0.14 μm, Hc: 700)
Oe, Bs: 6000G) and a speed of 10
The recording / reproducing characteristics were examined at m / s. As a result, F
e-Co-N (500Å) / In _0.2 Ga _0.8 As (5
0 Å) A multi-layer film with a thickness of 0.1 μm
To obtain a D ₅₀ of 0kFRPI.

[0019]

EFFECT OF THE INVENTION Fe-N or Fe-Co- of the present invention
It can be applied as a magnetic pole material of a thin film magnetic head containing N and the above-mentioned additional elements. In particular, by using it as a main magnetic pole material for a perpendicular magnetic disk, a head having high magnetic property and high recording / reproducing efficiency can be manufactured, and the recording density (D ₅₀ ) is 1
It is possible to obtain the characteristics of 00 KBPI or more. Further, if Cr, Mo, Nb, and V are added as an additive element in an amount of 5 at% or more, the corrosion resistance is improved, so that the magnetic characteristics of the magnetic film do not deteriorate during the head process.

[Brief description of drawings]

FIG. 1 is a graph showing the relationship between the film thickness of an Fe—N film and coercive force (Hc).

FIG. 2 is a graph showing the relationship between the film thickness of the Fe—N film and the crystal grain size.

FIG. 3 is a graph showing the relationship between the film thickness of the Fe—N film and the saturation magnetic flux density (Bs).

FIG. 4 is a graph showing the relationship between Fe ₁₆ N ₂ (220) and (103) diffraction peak intensities (T) and the film thickness of the Fe—N film.

FIG. 5 is a graph showing the relationship between the film thickness of the Fe—N film and the anisotropic magnetic field (Hk).

FIG. 6 is a film thickness of a Fe—Co—N film and a saturation magnetic flux density (B
The graph which shows the relationship with s).

FIG. 7 is a graph showing the relationship between changes in saturation magnetic flux density and additive element (M) concentration.

FIG. 8 is a sectional structural view of a perpendicular magnetic head.

[Explanation of symbols]

1: main pole, 2: substrate, 3: yoke, 4: coil, 5:
Protective plate

Claims (9)

[Claims] 1. A magnetic multilayer characterized in that a film containing a ferromagnetic element and a non-magnetic material having a lattice constant similar to that of a material containing the ferromagnetic element are alternately laminated. film. 2. The film containing the ferromagnetic element is a Fe—N binary film or a Fe—Co—N ternary film, and the nonmagnetic material is selected from MgO, GaAs, and In _0.2 Ga _0.8 As. The magnetic multilayer film according to claim 1, wherein the magnetic multilayer film is at least one. 3. The magnetic multilayer film according to claim 2, which has a coercive force of 20 Oe or less and a saturation magnetic flux density of 2.0 T or more. 4. The magnetic multilayer film according to claim 1, wherein epitaxial growth occurs between crystal grains in the film, each crystal grain has a different growth orientation, and a plurality of growth orientation relationships exist between the phases of the multilayer film. A magnetic multi-layer film characterized in that 5. The magnetic multilayer film according to claim 4, wherein the epitaxially grown film containing the magnetic element has lattice strain due to growth and magnetic anisotropy due to lattice strain. Multilayer film. 6. The magnetic multilayer film according to claim 2, wherein the film containing a ferromagnetic element is Cr, Mo which is a bcc forming element,
A magnetic multilayer film containing 5 at% or more of at least one of Nb and V. 7. A multilayer film according to any one of claims 1 to 6, wherein a lamination period of the multilayer film is equal to or more than a lattice constant of a material forming each layer, and a film thickness of the entire film is equal to or more than 100Å. A magnetic multilayer film. 8. A magnetic head comprising the magnetic multilayer film according to claim 1 for a main pole of a magnetic head. 9. A magnetic disk device comprising the magnetic head according to claim 8.