JPS6166220A - Thin metallic film type magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having good still durability particularly under low humidity and good C/N by incorporating the compd. of a magnetic matal into a thin magnetic metallic layer consisting of said compd. in such a manner that the average quantity of saturation magnetization of the magnetic metal and said magnetic layer attains the specific ratio of the quantity of saturation magnetization of the magnetic metal or below. CONSTITUTION:The magnetic layer 2 consisting essentially of the magnetic metal such as Co. Ni or Cr (including an alloy) and the magnetic compd. such as the oxide, nitride, sulfide or carbide thereof is formed on a substrate 1 consisting of plastic, metal, ceramics, etc. The layer 2 is formed by a sputtering method, vacuum-depositing method, etc. in such a manner that the average quantity of saturation magnetization of the entire layer attains <=60% of the quantity of saturation magnetization of the magnetic metal when the quantity of saturation magnetization changes in the thickness direction. The still life under low humidity is thus remarkably improved and the thin metallic film type magnetic recording medium having the improved C/N is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a metal thin film type magnetic recording medium that has both durability at low humidity and electromagnetic conversion characteristics.

Conventional Structure and Problems In recent years, metal thin film magnetic recording media have attracted attention as high-density magnetic recording media, and are gradually being put into practical use. It is known that the electromagnetic conversion characteristics of metal thin film magnetic recording media are extremely superior to those of conventionally used coating-type magnetic recording media during high-density recording, and are a promising material for next-generation magnetic recording. It is attracting attention as a recording medium. As described above, metal thin film magnetic recording media have excellent potential, but in order to make them more widespread as magnetic recording media, it is desired that their durability be improved. Typical known methods for improving durability include: (1) Overcoat (2) Surface shape control with no lubricant. Durability can be improved by using these methods, but on the other hand, these methods produce spacing loss and deteriorate electromagnetic conversion characteristics during high-density recording. For this reason, when considering the balance with electromagnetic conversion characteristics, it is not possible to obtain sufficient durability with conventional durability improvement methods, and there is a problem that durability is poor especially at low humidity where the protective effect of surface adsorbed water is weak. Was.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional problems and provides a metal thin film type magnetic recording medium that improves durability at low humidity while minimizing deterioration of electromagnetic conversion characteristics.

Structure of the Invention The present invention has a magnetic layer mainly composed of a magnetic metal and its compound, and the average saturation magnetization of the metal thin film magnetic layer is 60% or less of the saturation magnetization of the magnetic metal.

The present invention is a metal thin film type magnetic recording medium characterized by containing a magnetic metal and its compound in a proportion as high as 100%, and is capable of improving durability at low humidity while minimizing deterioration of electromagnetic conversion characteristics. .

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing the basic configuration of a metal thin film magnetic recording medium in an embodiment of the present invention. In FIG. 1, 1 is a substrate and 2 is a metal thin film magnetic layer.

Here, the substrate 1 is appropriately selected from materials such as plastic, metal, and ceramic. The metal thin film magnetic layer 2 is Go-based, GoNl-based, Goat-based, or Fe-based.

Fe-0r series, Fa-Go-Or series, Ni thread, N
The metal thin film magnetic layer 2 is formed by a vacuum evaporation method, a sputtering method, or a plating method.

The method is appropriately selected from CVD method, ion implantation method, ion blating method, impregnation treatment method, etc. The thickness of the metal thin film type magnetic layer 2 is 600 to 50 mm from the viewpoint of electromagnetic conversion characteristics and durability.
00 people is desirable. If the thickness of the metal thin film type magnetic layer 2 is increased, it depends on the compatibility with the head, but in high-density recording, the Br can be increased up to a thickness of 2,000 to 3,000 layers.
As δ increases, the reproduction output increases, and when the thickness is further increased, the reproduction output decreases due to thickness loss, and when the thickness exceeds so'oo, the reproduction output decreases significantly due to thickness loss. Further, the Br of the metal thin film type magnetic layer 2 according to the present invention is significantly lower than that of the conventional metal thin film type magnetic layer. Because the Br is low, the reproduction output decreases, but the output decrease during high-density recording is less dependent on Br (it depends on Ha, so the output decrease is small. However, as the recording density decreases, the reproduction output decreases significantly due to the decrease in Br. In order to ensure reproduction output at low recording density, it is necessary to increase the thickness δ of the metal thin film magnetic layer 2. Therefore, the thickness of the metal thin film magnetic layer 2 is desirably SOO to 50 μm, and more preferably a good high In order to obtain a high density recording/reproduction output, a film thickness of 500 to 3,000 is desirable, and more preferably a film thickness of 1 to 3,000 in order to obtain a good low density recording output.

The metal thin film magnetic layer 2 is a mixture of a ferromagnetic magnetic metal and its compound, and the mixing ratio is such that the average saturation magnetization of the metal thin film magnetic layer 2 is 60% or less of the saturation magnetization of the magnetic metal. This is a high percentage. Here, the average amount of saturation magnetization means that when there is a difference in the thickness direction, etc., the average amount of saturation magnetization is taken as the average of the entire thin metal film magnetic layer. As the proportion of antiferromagnetic material increases, the average saturation magnetization decreases, but as the average saturation magnetization decreases, the coercive force increases. This phenomenon is especially true for the Go system.

This is noticeable in the case of co-Ni type materials, etc., but the effect of increasing coercive force is effective when the average saturation magnetization of the metal thin film magnetic layer 2 is about 100 to 75% of the saturation magnetization of the magnetic metal.

In a region where the average saturation magnetization of the metal thin film magnetic layer 2 is 70% to 0% of the saturation magnetization 11 of the magnetic metal, there is an effect of increasing coercive force due to a decrease in the average saturation magnetization and an effect of decreasing coercive force due to disordered crystallinity. It is thought that they cancel each other out, and the coercive force does not change much. Therefore, due to changes in average saturation magnetization and changes in coercive force, the reproduction output during high-density recording is maximum when the average saturation magnetization of the metal thin film magnetic layer 2 is 80 to 76% of the saturation magnetization of the magnetic metal. If the amount of compounds increases further, the reproduction output during high-density recording will decrease. If the effect of increasing coercive force due to a decrease in average saturation magnetization is not significant, the reproduction output during high-density recording is highest when the magnetic metal is a single substance and does not contain any compound.

In the case of CO-based and Go-Ni-based magnetic metals, it is also known that magnetic noise can be reduced by reducing the average saturation magnetization amount. For this reason, even if the average saturation magnetization decreases and the reproduction output during high-density recording decreases, magnetic noise is further reduced.
/N may be improved.

Due to these effects, the highest C/N during high-density recording
In order to obtain this, the average saturation magnetization of the metal thin film magnetic layer 2 is about 75 to 70% of the saturation magnetization of the magnetic metal.

The present invention has an effect completely different from the improvement of electromagnetic conversion characteristics in Go-based and Go-Ni-based systems, and from the perspective of only reproduction output and C/N during high-density recording,
It is desirable that the average saturation magnetization of the metal thin film magnetic layer 2 is 90 to 7Q% of the saturation magnetization of the magnetic metal.If it is less than 60%, deterioration of electromagnetic change characteristics is observed, and even if the electromagnetic conversion characteristics are the same, Bs or Br is If it decreases, the film thickness δ will increase in order to obtain the same Brδ, which is disadvantageous in terms of productivity. However, when the average saturation magnetization of the metal thin film magnetic layer 2 is 60% or less of the saturation magnetization of the magnetic metal, the effect of improving durability at low humidity is remarkable, and this shows an effect that was completely unknown in the past. and electromagnetic conversion characteristics. The durability improvement effect of the present invention is due to the fact that as the mixing ratio of the magnetic metal and its compound approaches 1:1, the characteristics of the magnetic metal as a single substance become weaker.
It is presumed that this is due to a change in the crystal structure.

A more specific embodiment of the present invention will be described below.

(Example 1) Using polyethylene terefluoride with a thickness of 10 μm as a substrate, CoCo-N1 (20%) was coated with a diameter of 600 mm.
was deposited along the cylindrical can. For vapor deposition, the incident angle is 90'
The angle of incidence is started from the tangential direction, and the angle of incidence gradually decreases until the angle of incidence reaches 40'. 02 gas was introduced as an atmospheric gas during vapor deposition, and samples as shown in Table 1 were obtained by varying the amount of 02 gas introduced.

(Margin below) [Table 1] Coercive force H0, 23°C 10%Rh of the samples shown in Table 1
Still life in , reproduction output at recording wavelength 0.8 μm,
Figure 2 summarizes the C/N at a recording wavelength of 0.8 μm. The measurement was carried out using a rotating cylinder of φ4° having a ferrite head, and the reproduced output and C/N were expressed as OdB for sample E.

As is clear from Table 1, in terms of reproduction output and C/N, the optimal point is close to that of magnetic metals and there are not many compounds, but when considering the still life at 23°C 10%, there are many compounds. It is more advantageous.

As described above, according to this embodiment, when the average saturation magnetization of the metal thin film magnetic layer is 60% or less of the saturation magnetization of the magnetic material,
The still life at low humidity has been significantly improved by 1, and although the playback output is somewhat low, from the C/N perspective, it is -0.8 (from iB to -211B) from the maximum C/H value, and the electromagnetic conversion characteristics have deteriorated. is very small.

(Example 2) Using aromatic polyamide with a thickness of 20 μm as a substrate, G
o was deposited along a cylindrical can with a diameter of 500 mn. The deposition begins in the tangential direction at an angle of incidence of 90°, and gradually decreases to an angle of incidence of 36°. N2 gas was introduced as an atmospheric gas during vapor deposition, and the thickness of the deposited film and the amount of 02 gas introduced were varied to obtain samples as shown in Table 2. In Table 2, M, B, C, and D are obtained by changing the deposited film thickness δ, and A, B, C, and D are obtained by changing the ratio of six levels of nitrogen compounds, respectively. Third
The figure shows the still life of these samples under an environment of 23° C. and 10% Rh, and FIG. 4 shows the C/N of the reproduced signal at a recording wavelength of 0.8 μm. A rotating cylinder of φ40 having an amorphous head was used for the measurement. As a standard for 07H, the Mu-6 sample with the worst C/N was set to OdB.
Expressed as.

(Margin below) [Table 2] As is clear from Figures 3 and 4, from the viewpoint of the C/N of the reproduced output, it is better not to contain too many compounds, and in a 23°C 10% Rh environment. From the viewpoint of the life expectancy under the conditions, it is better to have more compounds. However, even in the region where the still life is good, the G/H deterioration is about 0.6 to 2 dB, and it is possible to achieve both the still life and the C/N.

As described above, according to this embodiment, by setting the average saturation magnetization of the metal thin film magnetic layer to 60% or less of the saturation magnetization of the magnetic metal, the still life at low humidity and the C/H of the reproduction output can be improved. It is possible to achieve both.

In this example, the effects were specifically shown for two types of samples, but it was confirmed that the same effects were obtained in combinations of the other materials mentioned above that constitute the present invention. Further, in the above embodiments, a magnetic tape was used as an example of the magnetic recording medium, but it may also take the form of a magnetic disk or a magnetic sheet without departing from the gist of the present invention. In addition to improving the durability of the present invention,
By using conventionally known overcoat, lubricant 2 surface shape control, etc., durability can be improved in various usage environments.

Effects of the Invention As described above, the present invention has a metal thin film magnetic layer mainly composed of a magnetic metal and its compound, and the average saturation magnetization of the metal thin film magnetic layer is 60% or less of the saturation magnetization of the magnetic metal. By containing magnetic metals and their compounds in such proportions,
It is possible to provide a metal thin film magnetic recording medium that has improved durability at low humidity while minimizing deterioration of electromagnetic conversion characteristics, and its practical effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a metal thin film magnetic recording medium in an embodiment of the present invention, FIG. 2 is a diagram showing electromagnetic conversion characteristics and durability in an embodiment of the present invention, and FIG. 3 is an embodiment of the present invention. FIG. 4 is a diagram showing the electromagnetic conversion characteristics in an example of the present invention. 1...Substrate, 2...Metal thin film magnetic layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Fig.2
421 So f volume Fig. 3 1 n-motyg raw/kidney 4m1i 7℃ magnetic and l meter/I
1 Figure 4

Claims (1)

[Claims] It has a metal thin film magnetic layer mainly composed of magnetic metals and their compounds, and contains magnetic metals and their compounds in such a proportion that the average saturation magnetization of the metal thin film magnetic layer is 60% or less of the saturation magnetization of the magnetic metal. A metal thin film type magnetic recording medium characterized by the following.