JPH07135111A - Multilayered magnetic film - Google Patents

Abstract

PURPOSE:To provide a multilayered magnetic film excellent in soft magnetic characteristics, wherein stable magnetic domain structure is obtained in a magnetic head magnetic pole form, and the optimum layer structure is about 200nm in thickness. CONSTITUTION:A multilayered magnetic film is formed on a substrate, and consists of a magnetic layer 1 having uniaxial magnetic anisotropy and nonmagnetic layers 2, 3 different in thickness. The nonmagnetic layer 3 is thicker than the nonmagnetic layer 2. A laminate constituted of the magnetic layer 1, the nonmagnetic layer 2, the magnetic layer 1 and the nonmagnetic layer 3 are alernately laminated. The thickness of the magnetic layer 1 is made 20nm or larger and 100nm or smaller. The thickness of the nonmagnetic layers 2, 3 is made 5nm or larger and 20nm or smaller. A soft magnetic film having periodic structure formed by repetition of a plurality of ferromagnetic materials can be used as the magnetic layer 1. Thereby a magnetic multilayered film which can be applied to the main magnetic pole film of a single magnetic pole type head and the yoke part of a yoke type MR head for vertical magnetic recording can be obtained.

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 used for a magnetic pole of a thin film magnetic head for writing and reading information on a magnetic recording medium, and particularly to a main magnetic pole film of a single magnetic pole type head for perpendicular magnetic recording. The present invention relates to a magnetic multilayer film effective for application to a yoke portion of a yoke type MR head.

[0002]

2. Description of the Related Art In recent years, magnetic recording devices such as fixed magnetic disk devices for computers, flexible magnetic disk devices, magnetic tape devices, etc. have been made to have a higher recording density. One of the key technologies is the development of a high sensitivity magnetic head. It is known that the sensitivity of the magnetic head strongly depends on not only the characteristics of the head material but also the magnetic domain structure of the magnetic pole magnetic film.

Here, taking a thin film magnetic head as an example, when the magnetic film forming the magnetic pole is a single layer film, the magnetic domain structure thereof is a return magnetic domain structure. Although the magnetization process of the return domain structure is caused by the magnetization rotation and the movement of the domain wall, the movement of the domain wall is suppressed in the high frequency region, so that the high frequency magnetic permeability of the entire magnetic pole is lowered. Further, since the domain wall moves discontinuously, the output waveform appears as waveform distortion. These phenomena have a greater influence on the head operation when the ratio of the triangular magnetic domains in the magnetic pole tip portion increases as the track becomes narrower. Suppressing such a phenomenon, that is, controlling the magnetic domain structure of a fine region such as the magnetic film of the head magnetic pole is an unavoidable problem in the development of a high-sensitivity magnetic head.

As one method, a study of controlling a magnetic domain structure by inserting a non-magnetic layer into a magnetic film to form a multi-layer is widely performed from both experimental and theoretical sides (for example, IEE transaction). On Magnetics, 24, 1988, 2045). According to this method, a single domain structure is realized by magnetostatic coupling that acts between the adjacent magnetic layers via the non-magnetic layer. Since the magnetization process in the single domain structure is only magnetization rotation and is not accompanied by the movement of the domain wall, it is possible to prevent the waveform distortion due to the discontinuous movement of the domain wall as described above, and the high frequency permeability. The decrease can be suppressed.

[0005]

In the conventional structure, however, considering a magnetic multilayer film composed of four magnetic layers, for example, as shown in FIGS. 2 (a) and 2 (b), The instability of the magnetic domain structure still remained because the adjacent magnetic layers were not coupled in one way through the non-magnetic layer. That is, in the example shown in FIG. 2B, since the uppermost magnetic layer and the lowermost magnetic layer have no paired magnetic layers, the magnetization process with respect to the external magnetic field behaves like a single layer film, and as a whole. Form a complex magnetic domain structure. Further, depending on the magnetization history, the states shown in FIGS. 2A and 2B appear randomly, which causes instability of the recording / reproducing operation. As a solution to this problem, for example, Japanese Patent Laid-Open No.
Japanese Patent Publication No. 49008 discloses a thin film magnetic head having a structure in which non-magnetic layers having different thicknesses are alternately laminated with magnetic layers interposed therebetween.

According to this method, the adjacent magnetic layers are easily magnetostatically coupled to each other through the thin non-magnetic layer, so that the instability of the magnetic domain structure described above can be eliminated. However, in this known example, the relationship between the thicknesses of the magnetic layer and the non-magnetic layer was not clearly shown, and the optimum layer configuration from the viewpoint of soft magnetic characteristics was unclear. Further, most of the studies on the laminated film of the magnetic layer / non-magnetic layer have been conducted on the magnetic film having a thickness of several μm used in a thin film head or the like (for example, JP-A-64-4908). The layer structure is directly applied to, for example, a main magnetic pole film of a single magnetic pole type head for perpendicular magnetic recording, or a magnetic film having a thickness of about 200 nm used for a yoke portion of a yoke type MR head. There is a drawback that you cannot do it.

An object of the present invention is to provide a magnetic multilayer film having a stable magnetic domain structure in a magnetic head magnetic pole shape and further having excellent soft magnetic characteristics, and its optimum layer structure is, for example, perpendicular magnetic recording. The present invention provides a magnetic multilayer film applicable to a main magnetic pole film of a single magnetic pole head for use in a magnetic head and a magnetic film having a thickness of about 200 nm used for a yoke portion of a yoke type MR head.

[0008]

According to the present invention, a first layer which is a soft magnetic film having uniaxial magnetic anisotropy, a second layer which is a non-magnetic film and has different thicknesses, and a third layer. And the third layer is thicker than the second layer, and the laminate including the first layer / the second layer / the first layer and the third layer are alternately formed. In the magnetic multilayer film having a laminated structure, the thickness of the first layer is 20 or more and 100 nm or less, and the thickness of the second layer and the third layer is 5 nm or more and 20 nm or less. Characterize. Further, a soft magnetic film in which the first layer has a periodic structure formed by repeating a plurality of ferromagnetic bodies may be used.

[0009]

The function of the present invention will be briefly described below. As shown in FIG. 1, the magnetic multilayer film of the present invention includes a magnetic layer 1 formed on a substrate 4 and having uniaxial magnetic anisotropy, and nonmagnetic layers 2 and 3 having different thicknesses. The non-magnetic layer 3 is thicker than the non-magnetic layer 2, and the non-magnetic layer 3 and the laminated body of the magnetic layer 1 / non-magnetic layer 2 / magnetic layer 1 are alternately laminated. By alternately arranging two types of nonmagnetic layers having different thicknesses in this manner, adjacent magnetic layers are easily magnetostatically coupled to each other via the thinner nonmagnetic layer (nonmagnetic layer 2). , The instability of the magnetic domain structure is eliminated as shown in FIG.
Further, by setting the thicknesses of the magnetic layer and the non-magnetic layer in the optimum range at this time, it is possible to provide a magnetic multilayer film having excellent soft magnetic characteristics as compared with a single layer film having the same thickness. It is possible.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention will be described with reference to the drawings. -Example 1-2 By an electron beam vacuum evaporation method using two evaporation sources, N
iFe film (Ni: 82% -Fe: 18%, weight%) and C
A NiFe / Cu multilayer film in which u films and alternate films were alternately laminated was prepared. A glass substrate is used as the substrate, and the substrate temperature is 1
It was set to 00 ° C. The film thickness of each layer was controlled by changing the opening / closing time of the shutter on each evaporation source. Degree of vacuum during vapor deposition is 1 × 1
It was 0 ^-9 Torr. During film formation, a DC field of 200 Oe was applied to the surface of the substrate using a permanent magnet to induce uniaxial magnetic anisotropy in the film. With the total thickness of the NiFe layer kept constant at 200 nm, various multilayer films having different NiFe layer thicknesses and Cu layer thicknesses were prepared, and the Ker effect microscope was used to observe the magnetic domain structure and measure the relative permeability in the hard axis direction (10 MHz). It was The sample for observing the magnetic domain structure was prepared by forming a magnetic head magnetic pole shape photoresist pattern on the film and performing ion etching in an Ar gas atmosphere. And FIG.
As shown in, the thickness of the magnetic layer is D and the thickness of the non-magnetic layer is b.
Then, the NiFe layer (magnetic layer) thickness is 20 nm or more 10
0 nm or less, Cu layer (non-magnetic layer) thickness is 5 nm or more and 20 n
A magnetic multilayer film having a single magnetic domain structure in a region of m or less and having a higher relative magnetic permeability (2000 or more) was obtained as compared with a single layer film having the same film thickness.

Next, a magnetic multilayer film in which two types of non-magnetic layers having different thicknesses were alternately arranged in the above-mentioned stacking range was prepared by the same method, and the stability of the magnetic domain structure was examined. The stability of the magnetic domain structure was evaluated by applying a DC magnetic field of a sufficient magnitude to saturate the film in the direction of the hard domain and then examining the remanent magnetization state using a Kerr effect microscope. As shown in FIG. 4, assuming that the thicknesses of the two types of nonmagnetic layers are b and c, respectively, when b ≧ c, the single domain state or the single-layer film-like return domain structure is irregular. An unstable magnetic domain structure was observed. On the other hand, b <
In the case of c, it was found that the magnetic domain structure stably holds the single domain state because the adjacent magnetic layers are sequentially coupled by two sets via the non-magnetic layer. -Example 2-3 An Fe / NiFe film (stacking period: 10 nm, Fe layer thickness = NiFe layer thickness = 5 nm, NiFe composition: Ni: 8) was formed on a substrate by an electron beam vacuum evaporation method using three evaporation sources.
2% -Fe: 18%, weight%) and a Cu film were alternately and continuously laminated to form a (Fe / NiFe) / Cu multilayer film. A glass substrate is used as this substrate, and the temperature of the substrate is 10
It was set to 0 ° C. The film thickness of each layer was controlled by changing the opening / closing time of the shutter on each evaporation source. The degree of vacuum during vapor deposition is 1
It was × 10 ^-9 Torr. During film formation, a DC field of 200 Oe was applied to the surface of the substrate with a permanent magnet to induce uniaxial magnetic anisotropy in the film. Then, with the total thickness of the Fe / NiFe layer set to 200 nm (constant), various multilayer films with different Fe / NiFe layer thickness and Cu layer thickness were prepared, and the magnetic domain structure was observed by the Kerr effect microscope and the ratio of the hard axis direction was measured. Magnetic permeability measurement (10 MHz) was performed.

A sample for observing a magnetic domain structure was formed by forming a photoresist pattern in the shape of a magnetic head magnetic pole on a film,
It was produced by performing ion etching in a gas atmosphere. The magnetic multilayer film of the second embodiment is similar to that of the first embodiment in that
Fe layer thickness is 20 nm or more and 100 nm or less, Cu layer thickness is 5
has a stable single domain structure in the region of 20 nm or more and 20 nm or less, and has a higher relative magnetic permeability (2
000 or more) was obtained.

In the above embodiment, Ni was used as the magnetic layer material.
Although the case where a material such as Fe or Fe / NiFe is used is shown, an Fe-based crystalline material, a Co-based amorphous material, or the like may also be used, and Cu is used as the nonmagnetic layer material.
However, other conductive materials such as Ti, V, Cr, Ta, W and Pt, and insulating materials such as Al ₂ O ₃ and SiO ₂ may be used. Furthermore, although the second and third layers are made of the same non-magnetic material in the above-mentioned embodiments, they may be made of different non-magnetic materials.

[0014]

As described above, according to the present invention, the magnetic head has a magnetic pole shape and has a stable magnetic domain structure.
A magnetic multilayer film having excellent soft magnetic characteristics as compared with a single layer film can be provided. Further, the optimum layer structure is used, for example, in the main magnetic pole film of the single magnetic pole type head for perpendicular magnetic recording or the yoke portion of the yoke type MR head.
It is possible to provide a magnetic multilayer film applicable to a magnetic film having a thickness of about nm.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view showing a conventional example.

FIG. 3 is a diagram showing changes in magnetic domain structure and relative permeability when the thicknesses of a magnetic layer and a non-magnetic layer are changed.

FIG. 4 is a diagram showing the stability of a magnetic domain structure when the thicknesses of two types of nonmagnetic layers are changed.

[Explanation of symbols]

 1 magnetic layer 2 and 3 non-magnetic layer 4 substrate

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01F 10/26

Claims (2)

[Claims] 1. A first layer, which is a soft magnetic film having uniaxial magnetic anisotropy, and a second layer and a third layer, which are nonmagnetic films and have different thicknesses, respectively. A magnetic multilayer having a structure in which a third layer is thicker than the second layer, and a laminate including the first layer / second layer / first layer and a third layer are alternately laminated. In the membrane, the thickness of the first layer is 2
A magnetic multilayer film having a thickness of 0 or more and 100 nm or less and a thickness of the second layer and the third layer of 5 nm or more and 20 nm or less. 2. The magnetic multilayer film according to claim 1, wherein the first layer is a soft magnetic film having a periodic structure formed by repeating a plurality of ferromagnetic bodies.