JP2543374B2 - Magnetic artificial lattice film - Google Patents

Description

The present invention relates to a magnetic artificial lattice film suitable for a magnetic pole of a magnetic head for a magnetic recording device.

[Conventional technology]

For example, in order to increase the recording density of a magnetic file device or the like, a magnetic recording medium having a large coercive force Hc is used, and the magnetic head has a high saturation magnetic flux density Bs capable of sufficiently magnetizing the magnetic recording medium, In addition, a magnetic material having good soft magnetic characteristics and capable of controlling the magnetic domain structure is required in order to efficiently focus the leakage magnetic flux from the magnetic recording medium.

As a magnetic head satisfying such conditions, a ring type head obtained by machining ferrite has been used conventionally. However, since the high saturation magnetic flux density and the fine processing are approaching their limits, a thin film magnetic head obtained by the fine processing technology and the thinning technology to which the photolithography technology is applied is currently used.

[Problems to be solved by the invention]

Conventionally, a NiFe alloy formed by vacuum deposition, sputtering, or plating has been used for such a magnetic pole film for a thin film magnetic head. However, since the saturation magnetic flux density is about 1 tesla, the coercive force Hc is 1000 oersted or more. It is difficult to record a magnetizing signal on a high coercivity medium.

The Fe film is promising as a film with a high saturation magnetic flux density to replace the NiFe alloy, but it cannot be used as it is as a magnetic pole film because it has a large coercive force and cannot have a magnetic domain structure suitable for the magnetic pole film. In addition, it has the drawback of being easily oxidized in air,
It is an obstacle to practical use.

On the other hand, as a method for controlling the soft magnetic domain structure of the Fe film, Fe
There is a method in which the second element such as C or Si is mixed as a guest by using as a host (eg, "FERROMAGNETIS" by Bozorth).
M ", DVNostrand Co.).

However, this method has a drawback that the saturation magnetic flux density Bs is lowered because C and Si are non-magnetic materials. Also, good soft magnetic properties can be obtained by forming a Fe film in a nitrogen atmosphere by the sputtering method (eg J.Appl.Phys. 6 ).
1 p3841 ('87)), but there is a problem that this film lacks thermal stability.

Therefore, these films have high saturation magnetic flux density, good soft magnetic characteristics (coercive force Hc is small), magnetic domain structure control is possible (magnetostriction constant λs ≈ 0), and oxidation is difficult.
There is a strong demand for a ferromagnetic film having excellent thermal stability.

By the way, recently, new materials have been actively researched. In particular, artificial lattice films have extremely thin layers, and by periodically stacking these layers, the original material In order to exhibit properties different from those of the bulk, it has attracted attention both in terms of physical properties research and application as a substance exhibiting new properties completely different from bulk properties.

The present invention has been made in view of the above points,
It is an object of the present invention to provide a magnetic artificial lattice film which has a high saturation magnetic flux density, exhibits excellent soft magnetic characteristics, has a magnetostriction constant of almost zero, and is also excellent in corrosion resistance and thermal stability.

[Means for solving problems]

Therefore, in the present invention, an Fe layer and a CoFe layer are alternately laminated on the substrate, or an Fe layer and a Co layer are alternately laminated on the substrate with a CoFe layer interposed to form a magnetic artificial lattice film.

In the present invention, a lattice film formed by alternately stacking Fe layers and CoFe layers or by alternately stacking Fe layers and Co layers with CoFe layers interposed is made into a single magnetic domain by a non-magnetic insulating film. It can also be configured as follows.

[Action]

Fe, Co, and CoFe are materials that have been conventionally used by themselves, but by stacking these, interaction between magnetic layers and disorder of Fe crystallinity occur, and coercive force Hc becomes small, which is favorable. It exhibits soft magnetic properties. Further, if each film thickness is set to an appropriate value, the magnetostriction constant λs can be set to near zero,
It is possible to control the magnetic domain structure.

〔Example〕

Examples of the present invention will be described below. FIG. 2 shows a deposition apparatus for producing an artificial lattice film. Reference numeral 1 denotes a target support, on which four targets can be mounted, and the targets can be switched by rotating them as indicated by arrows. Reference numeral 2 is an installation position of a substrate on which a magnetic film is to be deposited and formed, and 3 is an ion source. The production by the ion beam sputtering method is advantageous in that the operating vacuum is 1 × 10 ⁻⁴ Torr or less and the substrate temperature does not rise more than necessary.

FIG. 1 is a diagram showing a schematic structure of an artificial lattice film according to the present invention. 4 is a Co layer, 6 is a Fe layer, 5 is a CoFe alloy layer formed by mutual diffusion, and 7 is a substrate. The thicknesses of the Co layer 4 and the Fe layer 6 are t _Co and t _Fe , respectively, and one period t _p of the artificial lattice is defined by t _p = t _Co + t _Fe .

FIG. 3 shows changes in the magnetostriction constant λs when t _p is changed with t _Co = t _Fe . By changing (increasing) t _p , the magnetostriction constant λs continuously changes from positive to negative.
Although the magnetostriction constant λs of Co and Fe are both negative, the overall magnetostriction constant λs can take a positive or zero value. This is because the CoFe alloy layer 5 having a positive magnetostriction constant λs was formed at the boundary between the Co layer 4 and the Fe layer 6.

4A to 4C show the relationship between the magnetic domain structure observed in a NiFe alloy single film or the like and the sign (positive, negative, zero) of the magnetostriction constant λs. In the magnetic pole film of the magnetic head, in order to efficiently reproduce the signal from the medium, it is necessary to have a magnetic domain structure as shown in FIG. 4 (b), which has a magnetostriction constant λs =
It is required to be 0.

As described above, the magnetostriction constant λs of Fe and Co is negative, and CoF
Although the magnetostriction constant λs of the e alloy is positive, in the magnetic artificial lattice film obtained by laminating these so as to have a periodic structure by repetition, since the magnetic layers are magnetically connected,
The magnetic domain structure is determined by the sign of the magnetostriction constant λs of the entire film as in the single film.

FIG. 5 shows the dependence of the magnetostriction constant λs on the thickness of the Fe layer. Regardless of whether the Co layer thickness is 20Å or 5Å, the Fe layer thickness is 150Å
By the above, the magnetostriction constant λs = 0.

Figure 6 shows the dependence of the coercive force Hc on the thickness of the Fe layer. By setting the film thickness of the Co layer to 5Å, good soft magnetic characteristics with a small coercive force Hc of 1.5 Oersted can be realized.

Fig. 7 shows the dependency of the saturation magnetic flux density Bs on the Fe layer film thickness. Fe
Since it is based on, the value of about 2.15 Tesla (Fe saturation magnetic flux density Bs is 2.15 Tesla) was obtained.

FIG. 8 shows the relationship between the saturation magnetic flux density Bs and the Co layer thickness ratio (t _Co / t _p ). The broken line shows the saturation magnetic flux density of Fe Bs = 2.15 Tesla and Co
Saturation magnetic flux density Bs = 1.76 is connected. The data points above the dashed line are the CoFe alloy (Co
_This is because the saturation magnetic flux density Bs of ₅₀ Fe ₅₀ is 2.45 tesla).

FIG. 9 shows the dependence of the coercive force Hc and the magnetostriction constant λs on the Co layer thickness when the Fe layer thickness is fixed at 50Å. In order to obtain good soft magnetic characteristics, the film thickness of the Co layer is 10 for the Fe layer of 50Å.
Å It turns out that it is better to set below. From the state of change of the magnetostriction constant λs, the film thickness of the Co-Fe interdiffusion layer is 10Å
Expected to be moderate.

From the above results, it can be seen that the pure Co layer has a small saturation magnetic flux density Bs, a large coercive force Hc, and a large negative magnetostriction constant λs, which deteriorates the magnetic characteristics of the magnetic artificial lattice film. . Therefore, it is understood that the required Co layer has a minimum film thickness that alloys with the Fe layer. So Fe and CoFe
A magnetic artificial lattice of Fe / CoFe using an alloy as a target is also conceivable.

Figure 10 shows an example of the structure of a Fe / CoFe magnetic artificial lattice film. Fe
By changing the film thicknesses of the layer 6, the CoFe layer 5, and the composition of the CoFe layer 5, it is possible to realize the soft magnetic characteristics and the high saturation magnetic flux density Bs which are similar to or higher than those of the Fe / Co magnetic artificial lattice film.

FIG. 11 shows a [Fe, Co, CoFe] -based artificial lattice according to the present invention.
A configuration example of a multilayer film with a non-magnetic insulator such as SiO ₂ or Al ₂ O ₃ will be shown. Reference numeral 8 is a magnetic artificial lattice film, and 9 is a non-magnetic insulating film. By sandwiching the non-magnetic insulating film 9 between the magnetic artificial lattice films 8, the magnetic film can be made into a single magnetic domain.

That is, in the case of only the magnetic artificial lattice film having the laminated structure shown in FIG. 1 or FIG. 10, it is most static that the magnetic domain structure is a free-wheeling magnetic domain structure composed of a large number of magnetic domains as shown in FIG. It is in a stable state with low magnetic energy, and in this case, therefore, a return domain structure of multiple domains is formed instead of a single domain, but as shown in FIG. When a multilayer film sandwiching the film 9 is used, a magnetostatic coupling force works between the magnetic artificial lattice films 8 and, for example, in the magnetic artificial lattice film of the first layer from the surface, the magnetization direction is rightward in FIG. The layers are oriented leftward, the third layer is oriented rightward, the fourth layer is oriented leftward, and so on ... When facing, that is, in a single domain structure, the magnetostatic energy is the lowest and stable. It becomes a state. Thus, the magnetostatic coupling force acting between the magnetic artificial lattice films enables the magnetic artificial lattice film to have a single magnetic domain.

When only the magnetic artificial lattice film (the film structure shown in FIGS. 1 and 10) is used as the magnetic film for the magnetic head, the magnetic domain structure becomes a multi-domain return magnetic domain structure as shown in FIG.
What is most desirable in that the signal from the medium can be efficiently reproduced is the magnetic domain structure of (b) in (a), (b) and (c) of FIG.

On the other hand, if a multi-layer film of the magnetic artificial lattice film 8 and the non-magnetic insulating film 9 is used as the magnetic film for the magnetic head as shown in FIG.
The signal reproduction efficiency is further improved). The order of high signal reproduction efficiency and the relationship between them are as follows: [Magnetic domain structure of FIGS. 4 (a) and (c)] <[Magnetic domain structure of FIG. 4 (b)] <[FIG. 11 Domain structure].

Further, in the multilayer film structure of FIG. 11, since each magnetic layer becomes thin, eddy current loss can be suppressed and the frequency characteristic of magnetic permeability can be improved.

As described above, the [Fe, Co, CoFe] -based magnetic artificial film according to the present invention can realize good soft magnetic characteristics with a magnetostriction constant λs of zero, and at the same time, can realize a saturation magnetic flux density Bs of 2 Tesla or more. Further, these magnetic artificial lattice films contain Fe and Co and / or
Since it is sandwiched between CoFe, it has excellent corrosion resistance,
Further, even when the film forming temperature is 300 ° C., the magnetic characteristics do not deteriorate, and thus the thermal stability is excellent.

〔The invention's effect〕

As described above, the Fe, Co and CoFe magnetic artificial lattice films according to the present invention are optimized by optimizing the respective film thicknesses thereof.
Since a magnetic film having a high saturation magnetic flux density Bs, a small coercive force Hc, and a zero magnetostriction constant λs can be realized at the same time, a high density signal can be recorded in a high coercive force medium by using it as a magnetic pole material for a magnetic head. Has the advantage that it can also be efficiently reproduced.

In addition, the Fe layer and the CoFe layer are alternately laminated on the substrate, or the Fe layer and the Co layer are alternately laminated on the substrate with the CoFe layer interposed, so that it has excellent corrosion resistance and thermal stability. Since it is also excellent, there is an advantage that a magnetic component such as a highly reliable thin film magnetic head can be manufactured with high yield.

[Brief description of drawings]

FIG. 1 is a sectional view showing the outline of an Fe, Co, CoFe artificial lattice film according to an embodiment of the present invention, FIG. 2 is an explanatory view of a deposition apparatus for producing an artificial lattice film, and FIG. 3 is a magnetostriction constant λs. 4 (a) to 4 (c) are explanatory diagrams showing the sign and the domain structure of the magnetostriction constant λs, and FIG. 5 is the Fe of the magnetostriction constant λs.
FIG. 6 is a characteristic diagram showing the layer thickness dependence of the coercive force Hc, and FIG. 7 is a characteristic diagram showing the Fe layer thickness dependence of the saturation magnetic flux density Bs. Figure 8 shows the saturation magnetic flux density Bs and Co
FIG. 9 is a characteristic diagram showing the relationship with the layer thickness ratio, FIG. 9 is a characteristic diagram showing the Co layer thickness dependency of coercive force Hc and magnetostriction constant λs, and FIG.
FIG. 11 is a cross-sectional view showing a structural example (another embodiment) of a / CoFe artificial lattice film, and FIG. 11 is a structural example of a multilayer film of a [Fe, Co, CoFe] -based artificial lattice film and a nonmagnetic insulating film (further another It is a sectional view showing (Example). 1 ... Target support, 2 ... Substrate, 3 ... Ion source, 4 ... Co film, 5 ... CoFe film, 6 ... Fe film, 7 ... Substrate, 8 ... [Fe, Co, CoFe ] System artificial lattice layer, 9 ... Non-magnetic insulating layer.

Claims (2)

(57) [Claims] 1. A magnetic artificial lattice film characterized in that Fe layers and CoFe layers are alternately laminated on a substrate, or Fe layers and Co layers are alternately laminated on a substrate with a CoFe layer interposed. . 2. Fe layers and CoFe layers are alternately laminated, or Fe layers are formed.
The magnetic artificial lattice according to claim 1, wherein a lattice film formed by alternately laminating layers and Co layers with a CoFe layer interposed is made into a single magnetic domain by a nonmagnetic insulating film. film.