JPS62162223A - Thin film magnetic recording medium - Google Patents

Abstract

PURPOSE:To increase the coercive force Hc without decreasing the residual magnetic flux density Br, to increase the thickness of a magnetic layer, to decrease the thickness of the substrate Cr film, and to reduce the cost by adding Pt to the in-plane magnetized film of Co-Ni on a nonmagnetic substrate through the Cr film. CONSTITUTION:Glass is used as the nonmagnetic substrate 1, and a Cr thin film 2 and a Co magnetic film 3 are coated on the substrate. The relation of the thickness of the Cr film and the coercive force Hc of the magnetic film of 85Co-10Ni-5Pt obtained by adding Pt to the in-plane magnetized film of Co-Ni and having 0.08mum thickness is shown in Figure 5, and simultaneously compared with the cases where 80Co-20Ni and 70Co-30Ni are used. The coercive force Hc of 85Co-10Ni-5Pt is greater than those of 80Co-20Ni and 70Co-30Ni even when the thickness of the Cr layer is decreased. Besides, the residual magnetic flux density Br is plotted against the Ni-content is Figure 6, and the residual magnetic flux density Br of 85Co-10Ni-5Pt is greater than those of other compositions.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a thin film magnetic recording medium used in hard disk magnetic recording devices and the like.

BACKGROUND OF THE INVENTION In order to obtain excellent high-density magnetic recording characteristics, it is necessary to make the medium thinner, have a higher coercive force, and have a higher residual magnetic flux density. C is a magnetic material that satisfies this condition.

Magnetic thin films based on alloys are attracting particular attention. Methods for producing the medium include those using electroplating or electroless plating, and methods for producing a ferromagnetic thin film in a vacuum system such as vapor deposition, sputtering, and ion blating. Among these methods, the sputtering method in particular has a slower deposition rate than the vapor deposition method, but has the advantage that alloy films can be produced relatively easily, and various CO alloys are being researched and developed for use in disk media. In addition, recently, by using in-line continuous sputtering equipment,
A magnetic film 3 of Co or Co-Ni is deposited on a specific magnetic substrate 1 as shown in FIG. became. By using this in-line continuous sputtering apparatus, mass production of sputtered magnetic disks has become possible and has come into practical use.

Problems to be Solved by the Invention A metal thin film medium in which a Co--Ni in-plane magnetized film 3 is formed on a nonmagnetic substrate 1 via a Cr film 2 has a thin film that is a condition for obtaining high-density magnetic recording characteristics. ification.

It is well known that high coercive force and high residual magnetic flux density are possible. Incidentally, as a general method for evaluating the magnetic properties of a medium, the demagnetizing field parameter shown in the following equation (1) is used, and the larger the value, the higher the output reproduction due to the electromagnetic conversion characteristics.

Demagnetizing field parameter Br・δ/Hc... (1) Here, Br is the residual magnetic flux density E Gauss 20], and δ is the film thickness [
μm], Hc is coercive force [○e].

The coercive force Hc of the metal thin film medium is set to 700 to 8000, taking into consideration things such as reducing the burden of the recording current on the magnetic head.
It is said that e is preferable. However, as is clear from the relationship between the coercive force He and the underlying Cr film thickness shown in FIG. 2, when the magnetic layer thickness is 0.08 μm, the coercive force H'c is
In order to achieve 0 to 80o Oe, the film thickness of 8% Cr must be 0.5 μm or more in the case of Co-2ONi, and 0.5 μm or more in the case of Co-3ONi.
In the case of Co-2ONi, it is 0.17 μm or more, and Co-2ONi has the problem of high consumption of Cr material (and high cost. Figure 3 shows the thickness of Co-2ONi as a parameter.
The relationship between the coercive force He and the underlying Cr film thickness is shown. As is clear from FIG. 3, if the thickness δ of the magnetic film 3 is increased, the coercive force Hc becomes smaller, so it is also difficult to increase the thickness δ. Furthermore, as is clear from Fig. 2, when the Ni composition ratio is increased from 203 t% to 30 at%, the coercive force He becomes high (but as shown in Fig. 4, the residual magnetic flux density Br decreases, so the electromagnetic conversion It is known that the playback output with the characteristics is not high.

From the above, when the coercive force He is 700 to 8000e,
In addition, unless consideration is given to the magnetic material so as to increase Br.delta., it is difficult to obtain high reproduction output at low cost, and it is still not sufficient to obtain excellent high-density recording characteristics.

Means for Solving the Problems In order to solve the above problems, in the present invention, a Co--Ni in-plane magnetization film is formed on a non-magnetic substrate with a Cr film interposed therebetween.
This is an o-Ni in-plane magnetized film to which pt is added.

Effect: By the above means, it is possible to increase the coercive force He without reducing the residual magnetic flux density Br, and it is also possible to increase the thickness of the magnetic layer. In addition, the base Cr
Since the thickness of the film can be reduced, consumption of Cr material is reduced and costs can be reduced.

In addition, by further adding Ti, Co-3ONi
It is possible to create a magnetic material with corrosion resistance comparable to that of

EXAMPLE The present invention will be described in detail. Glass was used as the nonmagnetic substrate 1, and a Cr thin film 2 and a magnetic film 3 were deposited thereon. Figure 5 shows the case of 85Co-1ONi-5Pt with a film thickness of 0.0 as a magnetic film in which Pt of the present invention is added to a Co-Ni in-plane magnetization film.
The relationship between the coercive force He and the film thickness of the Cr film when conducted at 8 μm is shown, and at the same time, 80Co-2ON i and 70Co-
It is a figure compared with the case of 3ONi. As is clear from FIG. 5, the 85Co-1ONi-5Pt in which pt of the present invention is added to the Co-Ni in-plane magnetization film is the 80Co shown in the figure.
Even if the thickness of the Cr layer is smaller than that of -2ONi and 70Co-3ONi, the coercive force He is 700 to 8000e.

Moreover, FIG. 6 is a diagram showing the residual magnetic flux density Br versus the N i ML composition ratio.

As is clear from FIG. 6, 85Co-1 according to the present invention
ONi-5Pt is better than 80Co-2ONi and 70Co
It shows a larger residual magnetic flux density Br than 3ONi.

Therefore, 85C according to the invention.

-1ONi-5Pt is magnetically 80Co-2ONi
It is better than 70Co- in terms of consumption of the underlying Cr layer
It is now possible to use less than 3ON i.

FIG. 7 shows the coercive force HC when the Pt composition ratio is changed in the Co--Ni in-plane magnetized film added with pt of the present invention. In FIG. 7, the Cr film is assumed to have a thickness of 0.25 μm. In order to have a coercive force Hc of 7000e or more, Pt must be 2a
It can be seen that t% or more is required. Further, FIG. 8 shows the squareness ratio B r /B s when the composition ratio of Pt is changed. As is clear from FIG. 8, it was found that when 7 at% or more of Pt was added, the squareness ratio B r /B s decreased. Therefore, it is considered desirable that the composition ratio of Pt is 2 at% or more and 7 at% or less.

By the way, when the PT of the present invention is a Co-Ni in-plane magnetized film,
In order to increase the residual magnetic flux density Br, the Ni composition ratio is approximately 10
At%. Therefore, as shown in the corrosion resistance test in FIG. 9, it became clear that it was not as good as 70Co-3ONi. Therefore, in the present invention, we tried adding Ti, which has a strong corrosion resistance effect. As shown in Figure 9, Ti is la
By adding t%, 70 Co 30 N i
We were able to obtain a magnetic film with almost the same corrosion resistance. FIG. 10 is a diagram showing the coercive force when the Ti composition ratio is changed. If the Ti composition ratio is added to 3 at % or more, the coercive force decreases, so the amount of Ti added is 3 at % or more.
It has become clear that it is desirable that the content is t% or less.

Effects of the Invention As shown in the examples, since the present invention adds Pt to a Co-Ni in-plane magnetization film medium, it is different from the conventional Co-N
80C, which is an i-plane magnetic film medium.

-2ON i and 70Co-3ONi, it is clear that Br and He are larger in 27, and by adding Ti, it becomes a medium with corrosion resistance comparable to that of 70Co-3ONi, and it can be used as a medium for conventional sputtering magnetic disks. It has now become possible to supply magnetic disks that are superior to those of previous manufacturers.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view showing the structure of sputtered magnetic disks according to the present invention and conventional examples, and FIG. 2 shows the coercive force He of conventional Co-based magnetic thin films Co, 80Co-2ONi, and 70Co-3ONi and the relationship between the coercive force He and the underlying Cr film. A diagram showing the relationship between film thickness, Figure 3 shows 80Co-2O when the film thickness of the underlying Cr film is 0.5 am.
Figure 4 shows the relationship between the coercive force Hc of Ni and the film thickness of 80Co-2ONi.
FIG. 5 is a diagram showing the residual hourly density Br of 3ONi. The figure shows the dependence of the residual magnetic flux density Br on the Ni composition ratio, Figure 7 shows the relationship between the Pt composition ratio and the coercive force Hc in the Co-Ni-Pt of the present invention, and Figure 8 shows the dependence of the residual magnetic flux density Br on the Ni composition ratio. Invention Co-N
A diagram showing the pt composition ratio and squareness ratio Br/Bs (Br: residual magnetic flux density, Bs: saturation magnetic flux density) of i-Pt and Co-Ni-Pt-Ti, FIG. 9 is 85Co-1ON of the present invention.
i-5Pt and 84Co-1ONi-5Pt-Ti and conventional 70Co-3ONi,C. Figure 10 shows the corrosion resistance of Co-Ni-P of the present invention.
FIG. 3 is a diagram showing the relationship between Ti composition ratio and coercive force at tTi. 1...Nonmagnetic substrate 2...Cr thin film layer 3.
... Co-based magnetic alloy thin film layer 4 ... Protective film Figure 1 Figure 2 Lower Su Cr gL 171 possible f 4 a' (pen
7 Fig. 3 Fig. 4 Fig. 5 Peach Cr, l♂ (lJrQ) Fig. 6 Fig. 7 Pt (cLt :4) Fig. 8 h tαf-/, ] Fig. 9 10m6 (hemorrhoid)

Claims (4)

[Claims] (1) A thin film magnetic recording medium characterized in that a Co--Ni in-plane magnetized film is formed on a non-magnetic substrate via a Cr film, and Pt is added to the Co--Ni in-plane magnetized film. (2) The thin film magnetic recording medium according to claim 1, characterized in that the composition ratio of Pt is 2 at% or more and 7 at% or less. (3) The thin film magnetic recording medium according to claim 1, wherein Ti is further added to the Co--Ni in-plane magnetization film. (4) The thin film magnetic recording medium according to claim 3, characterized in that the composition ratio of Pt is 2 at% or more and 7 at% or less, and the composition ratio of Ti is 3.0 at% or less.