JPS5961106A - Magnetic memory body - Google Patents

Abstract

PURPOSE:To provide magnetic memory body being excellent in anti-corrosion, anti-abrasion and high recording density, by a method wherein non-magnetic alloy layer, thin film medium of specified alloy and a protective film are coated in sequence onto alloy substrate. CONSTITUTION:A non-magnetic alloy layer 2 of nickel-phosphorus alloy, for example, is coated by plating on a substrate 1 of aluminium alloy or the like, and surface of the base layer 2 is finished in mirror surface by mechanical grinding. Mirror grinding surface of the base layer 2 is coated with a metal magnetic medium 3 being a thin film medium of alloy of nickel, platinum and cobalt or alloy of iron, platinum and cobalt by means of high-frequency sputtering method, for example. A protective film 4 of SiO2 or the like is coated on the metal thin film medium 3 by means of high-frequency sputtering, for example.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic storage body used in a magnetic storage device (magnetic disk device, magnetic drum device, etc.).

Most of the magnetic storage bodies currently in practical use have discontinuous media. This discontinuous medium magnetic storage medium is
γ-FezO-1CrOt, Fe,'Fe-
C.

Magnetic storage media are manufactured by mixing and dispersing magnetic particles such as in a binder made of organic resin, coating it on a substrate, drying it, and firing it, so magnetic storage media are discontinuous at the level of the size of the magnetic particles. .

However, in recent years, due to the demand for higher recording densities in magnetic storage media, research and development of magnetic storage media with large coercive force made of continuous thin film media has been actively conducted.

This continuous thin film medium mainly consists of metal thin films made by methods such as plating, vacuum evaporation, sputter ion blating, etc., and Fe504, rF, e, etc. made by methods such as vacuum evaporation, sputtering, and ion blating.
Those made of metal oxide thin films such as yOs are known. Metal oxide thin films have a small residual magnetic flux density, so the demagnetizing field in the magnetic film is small.

Although the magnetization transition is small, large reproduction output cannot be obtained and there are restrictions in terms of high recording density. On the other hand, magnetic recording media made of metal thin films (hereinafter referred to as metal thin film media) have a higher residual magnetic flux density than metal oxide thin films and are promising, but they are susceptible to corrosion in poor atmospheres such as high temperature and high humidity, and are not fully developed. Corrosion-resistant metal thin film media are not yet known.

In view of the above-mentioned current situation, an object of the present invention is to provide a magnetic storage body having a metal thin film medium having an appropriate residual magnetic flux density of about 7000 Gauss, coercive force, excellent squareness, and extremely excellent corrosion resistance. be.

That is, in the magnetic memory of the present invention, an alloy substrate is coated with a non-magnetic alloy layer or a non-magnetic oxide layer, and an alloy consisting of nickel, platinum and cobalt or iron and platinum is coated on the non-magnetic alloy layer or non-magnetic oxide layer. and cobalt, and a protective film is further coated on the medium.

Next, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a partial cross-sectional view of the magnetic storage body of the present invention.

In FIG. 1, an aluminum alloy is most often used as the alloy substrate 1 of the magnetic memory body because it is light, has good workability, and is inexpensive, but a titanium alloy may be used in some cases. The surface of the base is machined to have small ridges (50 μm or less in the circumferential direction, 100 μm or less in the radial direction). Next, a non-magnetic alloy layer 2 of a tennickel-phosphorus alloy is coated on the base 1 by plating, and the surface of the base body 2 is mirror-finished to a maximum surface roughness of 0.03 μm or less by mechanical polishing. Next, an alloy consisting of nickel, platinum, and cobalt or iron is deposited on the mirror-polished surface of the base body 2 as a metal magnetic medium 3.

A thin film medium of an alloy consisting of platinum and cobalt is coated by radio frequency sputtering. Next, a protective film 4 typified by 5iO7 is coated on the metal thin film medium 3 by high frequency sputtering.

The metal thin film medium has a coercive force (c) of 300 to 120.
0,. Rusted 2), saturation magnetic flux density (BS) 8
000~12000G (glass), squareness ratio (Br/13
c) 0.7-09, coercive force squareness ratio (S*) 0.7-0
．． It exhibits excellent hysteresis characteristics as a magnetic recording medium in the range of 9. Moreover, the above properties are highly dependent on the amount of platinum and nickel or iron in the metal thin film medium.

Figure 2 shows changes in saturation magnetic flux density, coercive force, and atomic percent of nickel in a rectangular metal thin film medium using the atomic percent of platinum as a parameter. It can be used as a magnetic storage medium capable of high recording density within a range.

Figure 3 shows the dependence of coercive force on film thickness.
In a film made only of CO and PT without addition of 1, Hc is too high, resulting in poor override characteristics. It can be seen that the effect of adding Fe or Ni is large because the film thickness that enables high recording density is 10008 or less.

As described above, it has been found that a metal thin film made of a cobalt alloy containing 35 atomic percent or less of platinum and 20 atomic percent or less of iron or nickel is excellent as a magnetic recording medium. The protective film coated on the metal thin film medium 3 is preferably hard.

Osmium, Rudenium, Iridium, Manganese.

Metals such as tungsten, silicon, and titanium.

An oxide, nitride or carbide of tantalum or nitride, boron, carbon or an alloy of boron and carbon, or polysilicic acid is preferred.

Further, on top of the protective film 4, R-G
saturated or unsaturated hydrocarbons or fluorinated hydrocarbons, COOH, OH, NHt, COOR', 5i(OR'
),.

It is also possible to apply a lubricant consisting of a functional group such as CONH, fluorinated alkyl polyether, polytetrafluoroethylene telomer, or the like.

Next, the present invention will be explained by giving some examples.

Example 1 Non-magnetic alloy 2 was placed on a disc-shaped aluminum alloy disc 1 which had been finished with sufficiently small waviness (50 μm or less in the circumferential direction and 10 μm or less in the radial direction) by lathe processing and thermal straightening. The button was plated with a nickel-phosphorus alloy to a thickness of about 50 μm, and the nickel-phosphorus plating film was mirror-polished to a maximum surface roughness of 0.02 μm and a thickness of 30 μm. Next, on this nickel-phosphorus plating film, a metal magnetic medium 3 was applied using a high frequency spanner method at an argon pressure of 4 x 10-2 tons and a power density of 4.7 W/c.
r! A thin film of a cobalt alloy containing 20 atomic percent of platinum and 10 atomic percent of nickel was coated with a thickness of 500 mm. 5iO on top of this metal magnetic medium 3
A magnetic disk was fabricated by coating Z to a thickness of 200A by high frequency sputtering. The coercive force)-1c and residual magnetic flux density Br (BsXS) were 9000e and 7200G, respectively.

Example 2 Same as Example 1 except that 10% of platinum was used as the metal magnetic medium 3.
A magnetic disk was made by coating a cobalt alloy thin film containing 10 atomic percent of nickel and 10 atomic percent of nickel. H
c and Br are each 900 crp.

It was 9000G.

Example 3 A magnetic disk was fabricated in the same manner as in Example 1 except that the metal magnetic medium 3 was coated with a cobalt alloy thin film containing 7 atomic percent of platinum and 10 atomic percent of nickel. Hc
, Br is 500ce each.

It was 10,000G.

Example 4 A magnetic disk was produced in the same manner as in Example 1 except that the metal magnetic medium 3 was coated with a cobalt alloy thin film containing 35 atomic percent of platinum and 10 atomic percent of nickel. Hc and Br were each 500 and 7000G.

Example 5 The same procedure as in Example 1 was carried out except that the metal magnetic medium 3 was coated with a cobalt alloy thin film containing 20 atomic percent of platinum and 20 atomic percent of nickel.

Hc and Br were at 450 ce and 5200 G, respectively.

Example 6 A cobalt alloy thin film containing 10 atomic percent of platinum and 20 atomic percent of nickel A was coated as the metal magnetic medium 3 in the same manner as in example 1.

Hc and Br were 400 ce and 6400 G, respectively.

Example 7 The magnetic metal medium 3 was coated in the same manner as in Example 1, except that a cobalt alloy thin film containing 20 atomic percent of platinum and 10 atomic percent of iron was coated. Hc and Br are each 90
It was 0oe, 8000G.

Example 8 A magnetic disk was made in the same manner as in Example 2, except that iron was used instead of nickel. Hc*Br is 950■ each
, IQOOOG.

Example 9 A magnetic disk was made in the same manner as in Example 4, except that iron was used instead of nickel. He, Br are each 600 c
e, it was 8500G.

Example 10 A magnetic disk was made in the same manner as in Example 5, except that iron was used instead of nickel. Hc and r-1r are each 50
It was 0 ce and 6500 G.

Example 11 Same as Example 1, except that the surface of the aluminum alloy disk 1 was coated with aluminum oxide as a magnetic metal oxide layer by anodic oxidation as a non-magnetic alloy layer, and the aluminum oxide was coated with aluminum oxide to give the maximum surface roughness. Mirror-polished finish with a thickness of 0.02 μm.

Example 12 Magnetic disks were prepared in the same manner as in Example 1, except that each of the following materials was coated as a protective film to a thickness of 200 mm using the vine ivy method.

Example 13 A magnetic disk was prepared in the same manner as in Example 1, except that a 2.0 weight percent alcoholic solution of C tetrahydrofusilan was applied as a protective film by spin coating, and then baked at 200" C for 3 hours to produce a magnetic disk.

Example 14 A magnetic disk was produced in the same manner as in Example 5, except that the metal magnetic medium 3 was coated with a film thickness of 20.8 mm. Hc.

Br was 550 Ce and 5200 G, respectively.

Comparative Example A magnetic disk was produced in the same manner as in Example 1, except that the metal magnetic medium 3 was coated with a cobalt thin film to a thickness of 500 mm. I made a ri. He and Br are each 120■.

It was 12,000G. Using the magnetic disks shown in Examples 1 to 14 above, electromagnetic conversion characteristics, wear tests with heads, and environmental tests were conducted, and as a result, the following first-order characteristics were obtained. A wear test with the head was conducted through 20,000 contact start-stop tests, and no scratches were observed on the disk surface. In addition, in the 11J boundary test, the increase in the number of errors when left for six months at a temperature of 80'C and a relative humidity of 90% was all O, indicating that it had sufficient corrosion resistance. or. Regarding the comparative example, the coercive force was low and sufficient electromagnetic conversion characteristics could not be obtained, so for comparison, we immersed it in water at 25°C and examined the change in saturation magnetic flux density Bs, and the results shown in Figure 4 were obtained. It was found that the example had excellent corrosion resistance when compared with the comparative example. In FIG. 4, the vertical axis is the rate of change in the saturation magnetic flux density Bs (Bs/Bo, where Bo is the saturation magnetic flux density before immersion).
000 B P IO high-density recording was possible, but the comparative example had a small coercive force and could not achieve high-density recording.

From the above results, it was found that the magnetic memory of the present invention has excellent corrosion resistance (pot resistance), abrasion resistance, and high recording density characteristics.

[Brief explanation of drawings]

FIG. 1 is a partial cross-sectional view of the magnetic storage body of the present invention. In the figure, 1 is a substrate, 2 is a non-magnetic alloy metal, 3 is a metal thin film medium, and 4
is a protective film. Figure 2 is a characteristic diagram showing the changes in the saturation magnetic flux density, coercive force, and squareness of the metal thin film medium used in this magnetic storage medium depending on the atomic percent of nickel in the metal thin film medium, using the atomic percent of platinum as a parameter. be. FIG. 3 is a characteristic diagram showing the film thickness dependence of coercive force in the metal thin film medium used in the present magnetic memory. FIG. 4 is a characteristic diagram showing the rate of change in the saturation magnetic flux density of the metal thin film medium used in the present magnetic memory according to the water immersion time. Fig. 1 Hc (k Oe), Bs (KCr) Fig. 3 ΔC00,B Pf O,2 ・Co07 Ni O,j PtO,20C00
θ NL D, I Pt O, /mouth CD07Fe
O, f Pf: 0.2 Bladder thickness (wania 1 (n4 Kano)) Takamoema (Tatsu procedure amendment (voluntary) 1, Indication of the case 1981 Special Poetry Request No. 17169
No. 4 No. 2, Title of the invention: Magnetic storage device 3, Relationship to the amended person's case Applicant: Shibagousu-133-on 1-sae, Minato-ku, Tokyo (423) NEC Corporation Representative: Tadahiro Sekimoto 4, Agent 108 Sumitomo 31, Shibago J-37, Minato-ku, Tokyo, total 8. tl Hill 5, Drawing to be amended 6 Details of the amendment Figure 2 of the drawings attached to this application will be amended as shown in the attached drawing.

Claims (1)

[Claims] 1. A non-magnetic alloy layer or a non-magnetic oxide layer is coated on an alloy substrate, and an alloy consisting of nickel, platinum and cobalt or iron and platinum is coated on the non-magnetic alloy layer or non-magnetic oxide layer. 1. A magnetic storage body comprising a thin film medium made of an alloy consisting of cobalt and cobalt, and further comprising a protective film coated on the medium. 2. The magnetic memory according to claim 1, wherein the nonmagnetic alloy layer is nickel-phosphorus. 3. The magnetic memory according to claim 1, wherein the nonmagnetic metal oxide layer is aluminum oxide. 4. The protective film is made of osmium, ruthenium, iridium,
The magnetic memory according to claim 1, which is manganese or kungesten. 5. The magnetic memory according to claim 1, wherein the protective film is an oxide, nitride or carbide of silicon, titanium, tantalum or hafnium. 6. The magnetic memory according to claim 1, wherein the protective film is made of boron, carbon, or an alloy of boron and carbon. 7. The magnetic memory according to claim 1, wherein the protective film is made of polysilicate.