JPS60193124A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a small residual magnetic flux density, large coercive force, excellent squareness, high recording density and high S/N by constituting the titled medium of a non-magnetic layer coated with a thin film medium consisting of a cobalt alloy contg. simultaneously nickel and rhenium or coating the substrate with said medium via an underlying layer consisting of a non-magnetic metal. CONSTITUTION:A non-magnetic layer 2 is coated on a substrate 1 by plating of a nickel alloy and a thin metallic film medium 4 consisting of a cobalt alloy contg. simultaneously at least 10-30atom% nickel and 2-22atom% rhenium is coated as a metallic magnetic medium 4 on the layer 2 by a higher harmonic sputtering method. The thin metallic film medium manufactured in such a way has >=5,000 (oersted) coercive force, <=1,200 (gauss) satd. magnetic flux density, 0.7-0.9 squareness ratio and a ratio between the coercive force and the squareness ranging 0.7-0.9 and exhibits and excellent hysteresis characteristic as a magnetic recording medium.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention is a book relating to magnetic storage bodies that are commonly used in magnetic storage devices (i-disk devices, magnetic drum devices, etc.).

(Prior art and its problems) Currently, magnetic storage bodies are mainly put into practical use.

γ-Fe20B * CrO2e Fe, Fe-Co
It is manufactured by mixing and dispersing magnetic particles such as in a binder made of organic resin, coating it on a substrate, drying, and baking it, and the magnetic memory itself is at the level of the size of these magnetic particles. It is discontinuous. Therefore, the recording density is also 8000BP.
I and low density.

Therefore, in recent years, due to the demand for higher storage densities in magnetic storage media, research and development of magnetic storage media with high coercive force made of continuous thin film media has been actively conducted. This continuous thin film medium is mainly used for plating and vacuum deposition.

Manufactured using methods such as sputtering and ion blating.

Double Gourd Tea Maloney (W, T.

Maloney), IEEE Trans, Magn, MAG-15, 1979, Volume 15, page 1135 (IEEE Trans, Magn, MAG-15
, 1135 (1979) reported a magnetic storage medium in which a glass substrate was coated with chromium and a cobalt thin film was further coated on top of the glass substrate.
It is easy to corrode in a poor atmosphere of high humidity, and in this sense, it can be said that a metal thin film medium with sufficient corrosion resistance is not yet known. Furthermore, since the cobalt thin film medium has an excessively large residual magnetic flux density, its recording density characteristics and S/N ratio are poor (and it is not suitable for high-density recording).

In addition, Mr. Tu Chen, Hui E. E. Eatlands, Mag, 1979 Mug-15
Volume 1444 page (IEEE Tr;ans, Mag
.

MAG-15, 1444 (1979)) In a published paper, a magnetic recording medium coated with a cobalt alloy thin film containing rhenium has been reported, but the coercive force is the highest,
Since the recording density is as low as 500 Ga (oersted), the recording density is as low as 25,000 BPI, and like the cobalt thin film medium, the corrosion resistance is also poor.

(Objective of the Invention) In view of the above-mentioned current situation, the present invention has been developed to have far superior corrosion resistance, lower residual magnetic flux density, larger coercive force, superior squareness, higher recording density and higher S/ N
The object of the present invention is to provide a magnetic storage body made of a metal thin film medium that can obtain a high magnetic ratio.

(Structure of the Invention) That is, in the magnetic memory of the present invention, a nonmagnetic layer is coated on a substrate, and at least 10 to 3 nickel is coated on the nonmagnetic layer.
Coated with a cobalt alloy thin film medium simultaneously containing atomic percent rhenium and 2 to 22 atomic percent rhenium. Alternatively, in the magnetic memory of the present invention, a non-magnetic layer is coated on a substrate, and on the non-magnetic layer, at least 10 to 30 atomic percent of nickel and 2 to 22 atomic percent of rhenium are coated on the non-magnetic layer via a non-magnetic metal underlayer. At the same time, it is coated with a cobalt alloy thin film medium.

(Detailed explanation of configuration) Next, the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a partial sectional view of a magnetic storage body according to the first aspect of the present invention. In Fig. 1, aluminum alloy is used as the substrate 1 of the magnetic memory body because it is light and has good workability (it is the best because it is cheap), but titanium alloy is also used in some cases.The surface of the substrate is machined. The surface is finished with waviness smaller than the pressure (50 μm or less in the circumferential direction and 100 μm or less in the radial direction).
It is preferable that the base body 2 is coated with a phosphorus alloy by plating, and the surface of this base body 2 is mechanically polished to a maximum surface roughness of 0.03.
Mirror finish to micrometer or less.

Next, a metal thin film medium 4 made of a cobalt alloy containing at least 10 to 30 atomic percent of nickel and 2 to 22 atomic percent of rhenium is coated on the nonmagnetic layer 2 by high-frequency sputtering. The metal thin film medium made in this way has a coercive force ('
Hc) 5000e (Oersted) or more, saturation magnetic flux density (Bs) 12000G (Gauss) or less, squareness ratio (
Br/Bs)0.7-0.9. Coercive force squareness ratio (8'
) is in the range of 0.7 to 0.9 and exhibits excellent hysteresis characteristics as a magnetic storage medium.

Furthermore, the metal thin film medium 4 may be coated with a protective film.

The protective film coated on the metal thin film body 4 is preferably hard, and is made of metal such as osmium, ruthenium, iridium, manganese, or tungsten, or an oxide, nitride, or carbide of silicon, titanium, tantalum, or nofnium, or boron. , carbon or an alloy of boron and carbon, or polysilicic acid.

Furthermore, on top of the retaining film KR-G (R- is carbon number 10-40
saturated or unsaturated hydrocarbons or fluorinated hydrocarbons, G is C0OH, OH, NH2, C0OR', S i (O
It is also possible to apply a lubricant consisting of a functional group such as 3°C0NH, etc.

FIG. 2 is a partial sectional view of a magnetic storage body according to a second aspect of the present invention. The substrate 1 and the nonmagnetic layer 2 are prepared in the same manner as in FIG.
After mirror polishing the nonmagnetic layer 2, a nonmagnetic metal underlayer 3 typically made of chromium, molybdenum, tungsten, etc. is coated by high frequency sputtering. Alternatively, chromium, copper, or steel can be coated on 411 by plating. The nonmagnetic metal underlayer 3, typically made of chromium, molybdenum, or tungsten, increases the coercive force of the metal magnetic medium 4, as shown in FIG. However, the thickness of the base layer 3 is 0.8 μm.
Since the coercive force of the magnetic medium 4 is almost saturated at this point, it is useless to make it thicker than 0.8 μm. Here, the magnetic medium 4 is
It is similar to the magnetic medium cow in the figure. Non-magnetic metal base IvI3
In addition to chromium, molybdenum, and tungsten, there are also bismuth, tin, lead, aluminum, zinc, cadmium, gold, palladium, platinum, rhodium, iridium, ruthenium,
Metals such as osmium and rhenium are effective.

Figure 4 shows changes in saturation magnetic flux density, coercive force, and squareness depending on the atomic percent of rhenium in a metal thin film medium containing 20 atomic percent of nickel.
It can be used as a magnetic storage medium capable of high-density recording in the range of 22 at.%.

In Figure 5, the following Examples and Comparative Examples were immersed in water at 25°C to examine changes in the saturation magnetic flux density Ba. The horizontal axis represents the number of days of immersion in water, and the vertical axis represents the saturation magnetic flux density B8. The rate of change (B s /B o + where Bo is the saturation magnetic flux density before immersion) is shown. From Example 5 in FIG. 5, it was found that with regard to corrosion resistance, it is desirable that the total content of nickel and rhenium be 12 atomic percent or more.

As described above, it has been found that a metal thin film made of a cobalt alloy containing 10 to 30 atomic percent of nickel and 2 to 22 atomic percent of rhenium has excellent corrosion resistance and magnetic properties when used as a magnetic recording medium.

Pressure Sending The present invention will be specifically explained with reference to Examples and Comparative Examples.

Example 1 A non-magnetic layer 2 was formed on a disk-shaped aluminum alloy disk which had sufficiently small waviness (50 μm or less in the circumferential direction and 10 μm or less in the radial direction) and had sufficiently small waviness (50 μm or less in the circumferential direction and 10 μm or less in the radial direction) as the alloy disk 1. The phosphorus alloy is plated to a thickness of approximately 5011t, and the nickel-phosphorus plating film is coated with a maximum surface roughness of 0.02μm and a thickness of 30μ.
Mirror polished to m.

This nickel-phosphorus plating film was coated with chromium to a thickness of 0.3 μm as a metallic underlayer 3 by high-frequency sputtering.

Pressure: Argon pressure of 4 x 10-2 torr is applied to the chromium sputtered film as a metal magnetic medium 4 by high frequency sputtering method.
r, power density 1. A cobalt alloy thin film containing 201 atomic percent of nickel and 12 atomic percent of rhenium was coated with OW/ctI to a film thickness of 5ooX. Further, a 5 in 2 film was coated on top of this metal magnetic medium 4 to a thickness of 20× by high frequency sputtering to produce a magnetic disk.

The coercive force He and residual magnetic flux density Br (BsX8) were 850 Qe and 4600 G, respectively.

Example 2 A magnetic disk was prepared in the same manner as in Example 1 except that the metal magnetic medium 4 was coated with a cobalt alloy thin film containing 20 atomic percent of nickel and 4 atomic percent of rhenium.

Hc and Br are each 8000e.

It was 8800G.

Example 3 A magnetic disk was made using the same method as in Example 1, except that the metal magnetic medium 4 was coated with a cobalt alloy thin film containing 20 atomic percent of nickel (-st) and 18 atomic percent of rhenium.Hen B, r is 5500 each,
'1' It was 800G.

Example 4 A magnetic disk was fabricated in the same manner as in Example 1, except that the metal magnetic medium 4 was coated with a cobalt alloy thin film containing 10 atomic percent of nickel and 12 atomic percent of rhenium. ) (e and Br were 550 to 6300G, respectively.

Example 5 A magnetic disk was fabricated in the same manner as in Example 1, except that the metal magnetic medium 4 was coated with a cobalt alloy thin film containing nickel to atoms, <- cents, and rhenium di atoms. He and Br were respectively 5500t.

It was 10,000G.

Example 6 A magnetic disk was prepared in the same manner as in Example 1, except that the metal magnetic medium 4 was coated with a cobalt alloy thin film containing 30 atomic percent of nickel and 12 atomic percent of rhenium. He and Br were 5oOOe and 2800G, respectively.

Example 7 A magnetic disk was manufactured in the same manner as in Example 1, except that chromium was coated with a thickness of 0.1 μm as the nonmagnetic metal underlayer 3 by high frequency sputtering. He * B r 6000e.

It was 4600G.

Example 8 A magnetic disk was produced in the same manner as in Example 1, except that chromium was coated to a thickness of 0.5 μm as the non-magnetic metal underlayer 3. He
, Br were 11000* and 4600G, respectively.

Example 9 Same as Example 1, except that the non-magnetic metal underlayer 3 was made of ladle, silver, diamond structure carbon (C), and silicon.

Magnetic disks were made by coating them with germanium, manganese, and vanadium.

EXAMPLE 10 A magnetic disk was produced in the same manner as in Example 1, except that the nonmagnetic metal underlayer 3 was coated with an aluminum 20 atomic percent pm alloy.

Example 11 A magnetic disk was manufactured in the same manner as in Example 1, except that the nonmagnetic metal underlayer 3 was coated with 0.5 μm of chromium by electroplating.

Example 12 Same as Example 1, except that the surface of the aluminum alloy disk 1 was coated with aluminum oxide as a non-magnetic layer by anodizing, and the aluminum oxide was coated with a maximum surface roughness of 0.
Mirror polished to a depth of 0.02 μm.

Example 13 Magnetic disks were fabricated in the same manner as in Example 1, except that the following materials were coated as protective films to a thickness of 2ooX by sputtering.

Example 14 A magnetic disk was produced in the same manner as in Example 1, except that a tetrahydroxysila/20 weight percent alcohol solution was applied as a protective film by spin coating and then baked at 200° C. for 3 hours.

Example 15 A magnetic disk was produced in the same manner as in Example 1, except that molybdenum was coated as the non-magnetic metal underlayer 3. He,Br
were 900014.4600 G, respectively.

Example 16 A magnetic disk was manufactured in the same manner as in Example 1, except that tungsten was coated as the non-magnetic metal underlayer 3. He,
Br was 900 De and 4.600 G, respectively. Example 17 Same as Example 1, except that the metal magnetic medium 4 was directly coated on the non-magnetic layer 2 without covering the non-magnetic metal underlayer 3. and created a magnetic disk. He, Br are each 55
00e, 4600G.

Example 58 A magnetic disk was produced in the same manner as in Example 1, except that the protective film 5i02 was not coated.

Comparative Example 1 In the same manner as in Example 1, but without the metal base layer 3,
A magnetic disk was fabricated by coating a cobalt # film with a thickness of 5ooA as the metal magnetic medium 4. He.

Br was 1200e and 12000G, respectively.

Comparative Example 2 A magnetic disk was prepared in the same manner as in Example 1, except that the metal magnetic medium 4 was coated with a cobalt thin film with a thickness of 50A. He and Br are each 4500a.

It was 12000G.

Comparative Example 3 Same as Example 1, but without the metal base layer 3,
As the metal magnetic medium 4, a magnetic disk was fabricated by coating a cobalt alloy thin film containing 10 atomic percent rhenium with a film thickness of 500×. He + Br are each 5oo
oe, 63QOQ.

Comparative Example 4 In the same manner as in Example 1, however, a cobalt alloy thin film containing 10 atomic percent of rhenium was made into a metal magnetic medium.
A magnetic disk was made by coating with a film thickness of 0.00 kyu. He,
Br was 500 Da and 6300 G, respectively.

Using the magnetic disk shown in Example 1-18 above, electromagnetic conversion characteristics, head wear tests, and environmental tests were conducted, and as a result, the following characteristics were obtained. As for the wear test with the head, a 20,000-time start-stop test was performed, and no scratches were found on the disk surface. Furthermore, in the environmental test, when the product was left at a temperature of 80°C and a relative humidity of 90% for 6 months, the number of errors increased was 0, indicating that it had sufficient corrosion resistance. In addition, for comparative example IK, the coercive force was small and sufficient electromagnetic conversion could not be obtained, so for comparison, it was immersed in water at 25°C and the change in saturation magnetic flux density B8 was investigated, as shown in Figure 5. The following results were obtained, and compared to Comparative Example 1,
The examples were found to have excellent corrosion resistance. In Figure 5, the vertical axis is the rate of change of the saturation magnetic flux density B8 (Bs/Be, where B
e indicates the saturation magnetic flux density (before immersion). Moreover, Examples 1-1
High-density recording of 30,000 to 70,000 BPI is possible on the 8th disc, and the S/N is %30dB30dB.
However, Comparative Example 1 had a small coercive force and could not achieve high density recording.

In addition, in Comparative Example 2, electromagnetic conversion characteristics were obtained, but 1000
High-density recording of 0 BPI could not be achieved, and the S/N ratio was poor at 10 dB, making it impossible for practical use.

In addition, regarding the environmental test, the temperature was 80℃ and the relative humidity was 90℃.
The number of errors increased by 1,100 when left for several months, indicating that the corrosion resistance was extremely poor.

In addition, as in Comparative Example 1, the change in saturation magnetic flux density B8 was investigated by immersing it in water at 25°C, and as shown in Figure 5, the corrosion resistance was very poor, as in Comparative Example 1. Understood.

In addition, the electromagnetic conversion characteristics of Comparative Examples 3 and 4 are both 2500
Only low density recording of 0 BPI could be achieved. Furthermore, regarding the environmental test, the number of errors increased by 1000 when it was left at a temperature of 80°C and a relative humidity of 90% for 6 months, and Comparative Example 1.
Similar to No. 2, it was found that the corrosion resistance was very poor.

In addition, as in Comparative Examples 1 and 2, the samples were immersed in water at 25° C. to examine changes in the saturation magnetic flux density B8, and as shown in FIG. 5, it was found that the corrosion resistance was very poor.

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

[Brief explanation of drawings]

FIG. 1 is a partial sectional view of a magnetic storage body according to a first aspect of the present invention. In the figure, 1 is a substrate, 2 is a nonmagnetic layer, and 4 is a metal thin film medium. FIG. 2 is a partial sectional view of the second aspect of the present invention. In the figure, 1 is a substrate, 2 is a nonmagnetic layer, 3 is a nonmagnetic metal underlayer, and 4 is a metal thin film medium. Figure 3 shows the change in coercive force of the magnetic medium with respect to the thickness of chromium, molybdenum, and tungsten in the nonmagnetic metal underlayer when the thin metal film medium is a cobalt alloy containing 20 atomic percent nickel and 12 atomic percent rhenium. It is a diagram. Figure 4 shows the saturation magnetic flux density, coercive force, and squareness of the metal thin film in a cobalt alloy thin film medium containing 20 atomic percent nickel when the chromium in the nonmagnetic metal underlayer is 0.3 μm and when there is no nonmagnetic metal underlayer. FIG. 3 is a characteristic diagram showing changes depending on the atomic percent of rhenium in the medium. Fifth
The figure is a characteristic diagram showing the change in the rate of change of saturation magnetic flux density depending on the water immersion time of the present magnetic storage body in Examples and Comparative Examples. Representative patent attorney Uchihara 1 Figure 1 Figure 2 Figure 3 Figure 0 0.25 0.50 0.75 f, OQ lower xrd
3 Cr, No, W nolj) :” (,tt
m')) Figure 4 Rc Retention content, χ (42%) C0θ, 8-χ/V;

Claims (2)

[Claims] (1) A nonmagnetic layer is coated on a substrate, and a cobalt alloy thin film medium containing at least 10 to 30 atomic percent of nickel and 2 to 22 atomic percent of rhenium is coated on the nonmagnetic layer. Characteristic magnetic memory. (2) A non-magnetic layer is coated on the substrate, and at least one layer of nickel is coated on the non-magnetic layer via a non-magnetic metal underlayer.
1. A magnetic storage body comprising a cobalt alloy thin film medium containing rhenium in an amount of 0 to 30 atomic percent and rhenium in an amount of 2 to 22 atomic percent.