JPH01217723A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having a high recording density and high reproduced output by providing a magnetic Co alloy layer on an underlying layer consisting of Cr on a nonmagnetic substrate and alternately laminating the magnetic Co alloy layers and nonmagnetic layers thereon. CONSTITUTION:The magnetic Co alloy layer 3 is provided as a 1st layer on the underlying layer 2 consisting of the Cr provided on the nonmagnetic substrate 1 and the magnetic Co alloy layers 3 and the nonmagnetic layer 4 are alternately laminated thereon. Since the magnetic layers are laminated in such a manner, the film thicknesses of the respective layers are thinner than in the case of a single layer and the coercive force increases (high recording density). The high output is obtd. by totaling the film thicknesses of the respective layers. Since the Co alloy is used, the magnetic characteristics stabilize at the nonmagnetic substrate temp. (250 deg.C) than heretofore. The magnetic recording medium having the high recording density and the high reproduced output is thereby obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention particularly relates to a high recording density, high output magnetic recording medium.

[Conventional technology]

In recent years, with the increase in recording density of magnetic recording media, there has been a demand for magnetic recording media with higher coercive force.

In order to meet this demand, thin film media are being used as magnetic media instead of conventional iron oxide.

However, in order to improve the magnetic properties of a thin film medium, particularly to obtain a high coercive force, it is necessary to promote further thinning of the film. If the film is further made thinner in order to obtain a high coercive force, the product of residual magnetic flux density and film thickness becomes smaller. The product of residual magnetic flux density and film thickness is related to reproduction output, and the larger this value is, the greater the output is. Therefore, in order to obtain high output, the film thickness must be increased, which reduces the coercive force and reduces the recording density. Conversely, if you try to increase the recording density, the output will decrease. Single-layer C that achieves both output and recording density to some extent.
There is a magnetic recording medium provided with an o-alloy magnetic layer.

In addition, for example, Japanese Patent Publication No. 52-18396 and publications (
IEEE Tran@s Mag, MAG-15s
No-3* July 1979eP1135-113
7) shows a magnetic recording medium in which pure Co magnetic layers and nonmagnetic layers are alternately laminated.

[Problem to be solved by the invention]

However, the recording density and output of the magnetic recording medium having the single-layer Co alloy magnetic layer have now reached their limits.

The one in which pure Co magnetic layers and non-magnetic layers are alternately laminated (Japanese Patent Publication No. 18396/1983) uses pure Co for the magnetic layer, and the substrate temperature is heated to 250'C or higher. However, the film formation speed is very slow at only 1 minute when the film is formed by vapor deposition.

Also, another one (IEEE Tran@, Mag+
MAG-15No.

3, July 1979. P1135-1137)
The film is formed by sputtering method, but pure C
o (Since i7 is used, the coercive force is low, and the non-magnetic layer (
The film thickness of Cr) also needs to be considerably thick, which poses problems such as a high recording density cannot be obtained.

The present invention was made to solve these problems, and its entire purpose is to obtain a magnetic recording medium with high coercive force (high recording density) and high residual magnetic flux density x film L'l (high reproduction output).

[Means to solve the problem]

The magnetic recording medium of the present invention includes a non-magnetic substrate, an underlayer made of Cr provided on the non-magnetic substrate, and a Co alloy magnetic layer provided as a first layer on the underlayer, which is non-magnetic with the Co alloy magnetic layer. It is equipped with a laminate in which magnetic layers are alternately laminated.

[Effect]

When a single magnetic layer is used, it is difficult to achieve high recording density and high output at the same time because the coercive force changes depending on the film thickness.

However, in this invention, since the magnetic layers are laminated, the thickness of each layer is thinner than in the case of a single layer, resulting in a large coercive force (high recording density), and high output can be achieved by adding up the thickness of each layer. It will be done.

Furthermore, by using a CO alloy, problems associated with using pure CO can be solved.

〔Example〕

Example 1 @119 is a cross-sectional view of a magnetic recording medium according to an embodiment of the present invention, in which 111 is a nonmagnetic substrate, (2) is an underlayer made of Cr, (31 is a Co alloy magnetic layer, (41 is a non-magnetic layer,
(6) is a Co alloy magnetic layer (31) and a nonmagnetic layer (4).
It is a laminate in which 2 layers are alternately layered.

That is, a base layer (as 21 of Cr f2
After 000A sputtering, a Co-Nu alloy was formed to a thickness of 200A as a Co alloy non-magnetic layer (3) in the same sputtering tank at a speed of 1001y'n ln as @1M, and then sputtered in the same tank. Cr 50A was kneaded in a tank and sputtered as a non-magnetic layer (1lt41), and then Co-Ni was sputtered as a magnetic layer (3) in the same tank.
A laminate (5) was prepared by sputtering H1 to obtain a magnetic recording medium according to an embodiment of the present invention.
c) is 9000e, which is higher than that of the conventional magnetic recording medium using a single magnetic layer, which is approximately 700 to 8000e.

In addition, for the conventional He-9000e, Brδ is 50
0, whereas the magnetic recording medium of the embodiment of the present invention shows a high value of 930.

Example 2 After forming the underlayer (up to 21) in the same manner as in Example 1, Co was immediately added as the first magnetic layer (3) in the same tank.
After forming a -N1-Cr alloy to a thickness of 200A, 50A of Cr was sputtered as a non-magnetic layer (4) in the same tank, and then Co- A magnetic recording medium of this embodiment of the present invention was obtained by sputtering Nl-Cr, and exhibited properties comparable to those of embodiment 1.

Example 3 After forming a film up to the base layer (2) in the same manner as in Example 1, the first layer of magnetic NI (C as 31) was immediately added in the same manner.
After forming the o-Ni alloy to a thickness of 20OA, sputtering was continued in the same tank with Cr 50A It as a non-magnetic layer (4+), and then Go-Ni-Cr was sputtered as a magnetic layer (3) in the same tank. was sputtered to obtain a magnetic recording medium of yet another example of the present invention, which exhibited properties comparable to those of Example 1.

As the nonmagnetic substrate for the magnetic recording medium of the present invention, for example, Δヱ, glass, ceramic, etc. are used, and it is desirable to form the magnetic layer and the nonmagnetic layer by heating to /aK of 250° C. or less, for example. .

FIGS. 2(a)*(b) and (e) show the magnetic recording medium of the embodiment of this invention obtained in the same manner as in embodiment 1 except that the nonmagnetic substrate 6λ was changed. Seijj
(Coercive force (He) due to non-magnetic substrate 6λ degrees (°C)
Change (Figure 2 (a)), Change in residual magnetic flux density × magnetic layer thickness (BrJ) due to nonmagnetic substrate temperature ('C) (N2 figure (b)), Ya and nonmagnetic substrate M degree ('C) This is a characteristic diagram showing the squareness ratio (So) change (Figure 2 (C)) due to It can be seen that the magnetic properties are stable at a temperature lower than the conventional temperature (250° C. or higher).

As the Co alloy magnetic layer according to the magnetic recording medium of the present invention, for example, Co-Ni5 Co -N%-Cry Co
-Nl-Mow Co -N1-W and Co-Pt
At least one of these is used, and the film thickness is 200~
A range of 600A is desirable. If it is less than 200A, it becomes difficult to form a film, and if it is more than 600A, the coercive force becomes small.

Examples of the nonmagnetic layer of the magnetic recording medium of the present invention include Crs Cu, Au, Age Pde Pte
At least one of Aje V and TI is used, and the film thickness is preferably in the range of 50 to 300 mm. 50A
Below that, the film formation becomes difficult, and above 300 A, each magnetic layer is made independent and becomes a single layer. N3 diagram (1), (b)
, (p) is a magnetic recording medium of an example of the present invention obtained in the same manner as in Example 1 except that Cr was used for the nonmagnetic layer (4) and the film thickness was changed. (A)
Coercive force (Hc) change due to (Figure 3 (a)), residual magnetic flux density x magnetic layer 1 equivalent thickness (BrJ) change due to Cr film thickness (A) (Figure 3 (b))% and Cr film thickness ( FIG. 3 is a characteristic diagram showing changes in squareness ratio (So) due to A) (FIG. 3(C)), in which the horizontal axis shows the Cr film thickness and the vertical axis shows each magnetic property. According to this, it can be seen that each magnetic property is stable when the nonmagnetic film thickness is 50A or more.

In the above embodiment, a total of two layers of magnetic material 1111 are laminated, but it is possible to laminate more layers and the desired purpose can be achieved.

Further, in the above embodiment, film formation was performed by sputtering, but film formation by vapor deposition or the like may be used.

〔Effect of the invention〕

As explained above, the present invention includes a non-magnetic substrate, an underlayer made of Cr provided on the non-magnetic substrate, and a Co alloy magnetic layer provided as a 9:1 layer on the underlayer, and the above Co alloy magnetic layer. By using a laminate in which non-magnetic layers are alternately laminated, a magnetic recording medium with high recording density and high reproduction output can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a magnetic recording medium according to an embodiment of the present invention.
FIGS. 2(a), (b), and (C) are characteristic diagrams showing changes in magnetic properties depending on the temperature of the nonmagnetic substrate during film formation in the magnetic recording medium of the embodiment of the present invention, and FIG. 3(a) . (b) and (C) are characteristic diagrams showing changes in magnetic properties depending on the thickness of the nonmagnetic layer in the magnetic recording medium of the example of the present invention. In the figure, +11 is a nonmagnetic substrate, (2) is an underlayer made of Cr, (3) is a Co alloy magnetic layer, (4) is a nonmagnetic layer, and 1fil is a laminate.

Claims (1)

[Claims] A nonmagnetic substrate, an underlayer made of Cr provided on the nonmagnetic substrate, and a Co alloy magnetic layer provided as a first layer on the underlayer, and the Co alloy magnetic layer and the nonmagnetic layer were alternately laminated. A magnetic recording medium with a laminate.