JPH02223009A - magnetic recording medium - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to improvement of a metal thin film type magnetic recording medium using Fe.

(Prior art) A so-called metal thin film type magnetic recording medium, in which a thin film of ferromagnetic metal is formed on a nonmagnetic substrate by means such as vacuum evaporation or sputtering ion blating, is a magnetic recording medium that uses a binder. Efforts are being made to put it into practical use because it has various advantages in addition to being able to achieve higher recording density than recording media.

Ferromagnetic metals such as Fa, Co5Ni, and Cr, and alloys mainly composed of these ferromagnetic metals are often used as metals to create such metal thin film type magnetic recording media. , among which Co alone or C
O-based alloys are often used as magnetic recording media because of their high performance.

On the other hand, among the above-mentioned ferromagnetic metals, Fe is C.

Although it has various advantages such as lower material cost, better S/N ratio when used as a magnetic recording medium, and lower distortion rate than alloys of It has the drawbacks of large thickness dependence, small squareness ratio, and insufficient corrosion resistance.

(Objective of the Invention) Therefore, the object of the present invention is to take into account the film thickness dependence of the coercive force of the inexpensive ferromagnetic metal Fe, secure the desired magnetic output, and improve the squareness ratio and coercive force. In order to reduce the deterioration of the Fe thin film layer, it is necessary to have two or more Fe thin film layers, and when the above-mentioned required Fe film thickness is obtained, a ferromagnetic material is used to compensate for the decrease in characteristics such as the squareness ratio and coercive force of Fe. The object of the present invention is to provide a magnetic recording medium that eliminates the above-mentioned deterioration of the characteristics of Fe itself and maximizes the advantages of Fe by providing the metal Co alone or an alloy mainly composed of Co as an intermediate layer. .

(Structure of the Invention) The magnetic recording medium of the present invention has two or more Fe layers on a non-magnetic substrate.
It is characterized in that a thin film layer and a thin film layer of Co alone or an alloy mainly composed of Co inserted between each FeFiflu layer are laminated.

Hereinafter, the present invention will be described in detail with reference to the drawings. As shown in FIG. The main alloy thin film layer 4 and the second Fef!
Each layer of WA 115 is sequentially laminated. The example shown in Fig. 1 consists of two Pe thin film layers and a Co single or Co-based alloy thin film layer inserted between the two thin film layers, but three or more Fe thin film layers are used. form each F
A thin film layer of Go alone or an alloy mainly composed of Co may be inserted between e 'iii @li.

The non-magnetic substrate 2 mentioned above may be a heat-resistant synthetic resin film such as a polyethylene terephthalate film, a polyimide film or a polycarbonate film, a metal foil such as an aluminum foil, or a non-magnetic dielectric film such as a polyethylene terephthalate film, a polyimide film or a polycarbonate film.
It is possible to use copper foil, copper foil, stainless steel foil, etc., or glass or ceramic. Among these, when producing a magnetic recording medium in the form of a tape, it is preferable to use a polyethylene terephthalate film having a thickness of 4 μm to 25 μm in terms of heat resistance, tensile strength, and dimensional stability.

The first Fe thin film layer and the second Fe thin film layer are basically under similar conditions. Furthermore, the reason for providing the first FsEl film layer and the second Fe thin film layer is that in the case of an Fe thin film, a certain film thickness (at least 500 Å or more, preferably 2000 Å or more) is necessary to obtain the desired magnetic output. This is because, if the Fe thin film layer is formed all at once, a film thickness that produces the desired magnetic output can be ensured, but good results cannot be obtained in terms of characteristics such as squareness ratio and resistive 61 force. The first and second Pa thin film layers can be provided by means such as vapor deposition using Fe as a vapor deposition source, and while ensuring the film thickness to obtain the desired magnetic output, the squareness ratio and coercive force are Use means that satisfy the following characteristics.

That is, instead of forming the desired film thickness in one step, a method is used in which the film thickness is formed in two steps without deteriorating the characteristics such as the squareness ratio and coercive force. Further, when performing vapor deposition, it is preferable to set the angle between the normal line of the substrate to be vapor-deposited and the metal vapor deposition flow to be larger than 0°, so as to perform so-called oblique vapor deposition. According to the research conducted by the present inventors, the Fe thin film formed at the angle between 45° and 80° has a thickness of 200 Å to 2000 Å, more preferably 300 Å to 1000 Å. It was found that its magnetic properties are excellent. If the number of people is less than 200, the thin film is not formed properly and sufficient magnetic flux cannot be obtained, and furthermore, the shape anisotropy effect, which is one of the factors that affects the improvement of coercive force, has a small effect, so the coercive force is small. However, if the number exceeds 2,000, the tilted pillars of the Fefjl film will grow too much, and the tops of adjacent tilted pillars will coalesce, and in any case, outside the above range, both the squareness ratio and coercive force will decrease. It is.

The intermediate layer between the first Fe thin film layer and the second Fe thin film layer, which is made of Co or an alloy thin film layer mainly composed of Co, serves as an intermediate layer that separates the Fe thin film layers. In addition, at this time, the good magnetic properties of the ferromagnetic metal Co alone or in an alloy mainly composed of Co (such as high coercive force and squareness ratio) come into play, improving the magnetic properties of the entire recording layer. Therefore, this C is formed between the first Pe thin film layer and the second Fe thin film layer.

An intermediate layer of Co alone or an alloy mainly composed of Co is provided.

Furthermore, the above-mentioned Co alone or Go-based alloy thin film layer may include Co alone, Go-Ni, Go-CrS, etc.
Co-Cu, co-Au, Co-Y, Co-L
a.C.

-Pr, Go-GdS Co-3II, Co-PL, C
o-Dy, C.

The first and second
Similarly to the Pe thin film layer, it is preferably formed by oblique evaporation at an angle of 45° to 80'' to a thickness of 200 Å to 2,000 Å for the above-mentioned reasons. It is preferable to add N1 so that N1=9515~65/35<weight ratio) in consideration of price, and the coercive force of the Co-based metal thin film layer is higher than that of other Fe.
It is preferable to appropriately determine the angle of oblique deposition so as to substantially match the coercive force of the thin film layer.

In the present invention, since a thin film layer of Co alone or an alloy mainly composed of Co is provided between the Fe thin film layers, magnetic properties and corrosion resistance are improved. First, the reason why the coercive force characteristics improve is that each F
This is thought to be because the magnetic properties of each Fefl film layer produce an additive effect because the e''Fl film layers are independent of each other through the intermediate layer. Even if the Fen film layer is simply thickened, the coercive force and square shape As mentioned above, the ratio decreases, but even if two layers of Fen film layers having the above thickness range are laminated in two steps, the coercive force and squareness ratio will still decrease. , the next Fe thin film layer is formed with a tendency to extend the inclined columnar structure of the underlying Fe thin film, resulting in the same total thickness as if it were formed in one step, exceeding the above-mentioned preferred thickness range. It is thought that this is because the

In addition, the reason why the coercive force and squareness ratio are improved in the present invention is as follows.
This is thought to be because the coercive force and squareness ratio of the Co alone or Co-based alloy thin film layer itself are good, so that the coercive force and squareness ratio of the entire magnetic recording medium are improved.

Furthermore, the reason why the corrosion resistance is improved is that the electrochemical properties of Pe are similar to those of Go alone or an alloy mainly composed of Co, and it is better to use Co alone or an alloy mainly composed of Co. This is thought to be because the inclined columns are formed more densely than in the case of Fe.

Although the explanation has been given above mainly on the one shown in FIG. 1, means such as forming a protective layer on the surface of the magnetic recording medium may be added.

(Effects of the Invention) Since the magnetic recording medium of the present invention has an intermediate layer interposed between the Fe thin film layers, it can mainly suppress the decrease in coercive force that conventionally occurs when a constant film thickness is obtained using Fe alone. Furthermore, a decrease in the squareness ratio can also be suppressed.

Furthermore, by using the ferromagnetic Co alone or an alloy mainly composed of Co in the intermediate layer, the coercive force and squareness characteristics of the entire recording layer are improved, and the corrosion resistance is also improved. It is effective.

Examples are given below to more specifically illustrate the present invention.

A polyethylene terephthalate film with a thickness of 6 μm was used as the substrate, and a Pe thin film with a thickness of 850 μm was first formed on the film by oblique vapor deposition with a minimum incident angle of 65°. Next, Co:Ni-80:2 was deposited on the Fe thin film.
Co-N with a thickness of 400 mm was obtained by oblique evaporation using a Go-Ni alloy with a weight ratio of 0 (weight ratio) and a minimum incident angle of 45°.
An interlayer film of i-alloy was provided. Furthermore, an Fe thin film was provided on the Co--Ni alloy thin film in the same manner as in the above-described Fe thin film formation.

- The substrate was the same as in Example 1, and a 850-thick Pa thin film layer was formed twice in the same manner as in Example 1.

Upper 1iJLL The intermediate film was an aluminum vapor-deposited film having a thickness of 300 mm, and the other conditions were the same as in Example 1.

Tables 1 and 2 show the results of evaluating the magnetic properties and corrosion resistance of the magnetic recording media obtained in the above Examples and Comparative Examples.

table magnetic properties

[Brief explanation of the drawing]

No. FIG. 1 is a sectional view of an embodiment of the magnetic recording medium of the present invention. magnetic recording medium non-magnetic substrate 3. Fa thin film layer ・Co alone or Co-based alloy thin film layer

Claims (2)

[Claims] (1) Magnetic recording characterized by laminating two or more Fe thin film layers on a nonmagnetic substrate and a thin film layer of Co alone or an alloy mainly composed of Co inserted between each Fe thin film layer. Medium. (2) The magnetic recording medium according to claim (1), wherein each Fe thin film layer has a thickness of 200 Å to 2000 Å.