JPH0311531B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording body having a film of a magnetic material whose magnetization is perpendicular to the thin film surface, that is, a perpendicularly magnetized film, and a method for manufacturing the same.

Recently, perpendicular magnetic recording and magneto-optical recording have been attracting attention and research as new magnetic recording methods capable of high-density recording, but the media used in these methods have magnetic anisotropy in the perpendicular direction. Be prepared and
It is necessary to use a so-called perpendicular magnetization film that satisfies the conditions Ku⊥≧2πMs ² or Hc⊥>Hc, Br⊥>Br.

As is conventionally known, Co has a large magnetocrystalline anisotropy in the C-axis direction of the HCP structure.
If you try to obtain a perpendicularly magnetized film by utilizing this property, you will find that the crystal orientation is such that the C-axis is almost perpendicular to the film surface, and that the magnetocrystalline anisotropy
It is necessary to satisfy two conditions: Ku is larger than the demagnetizing field 2πMs ² in the perpendicular direction of the thin film. However, since the Co thin film has a large value of saturation magnetization Ms, the above condition is not satisfied and the film cannot be a perpendicularly magnetized film.

On the other hand, one of the most popular perpendicular magnetization films has been a Co--Cr thin film, which has been produced by sputtering and vapor deposition. However, since the sputtering method has a low deposition rate, there are problems in terms of mass production for media that are used in large quantities, such as floppy disks and magnetic tapes. In addition, in the vapor deposition method, Co and Cr
It is difficult to control the stable Cr composition over a long period of time because the vapor pressure of
Perpendicular magnetic properties can only be obtained by vapor deposition while heated to ~300°C, and a perpendicular magnetic film cannot be obtained at room temperature without heating the base material. Therefore, a heat-resistant material must be used as the base material. This may cause inconveniences such as failure.

In view of the above-mentioned points, the present invention provides a perpendicular magnetic recording body having a perpendicular magnetization film made of a new type of composition of Co-Ni-O, in which a perpendicular magnetization film is applied directly to the surface of a non-magnetic base material, or Co _x Ni _y through thin film layer
O _z (x, y, z are at%, 0<y<40, 15<
Co-Ni expressed as z<50, x+y+z=100)
-0 composition, the crystal structure has a columnar grain structure with the C axis of the HCP structure oriented in the vertical direction, and the crystal magnetic anisotropy ku⊥ is larger than the demagnetizing field 2πMs ² in the vertical direction.

Furthermore, a second invention provides a method for manufacturing the above-mentioned novel perpendicular magnetic recording body, in which a non-magnetic substrate surface is coated with:
Or on the surface of a soft magnetic thin film layer previously formed on that surface,
Co and Ni atoms are evaporated so as to be incident substantially perpendicularly, and at the same time O ₂ gas is introduced to form Co _x Ni _y O _z (where x, y, and z are at%, 0<y<40, 15 ＜z＜
50, x+y+z=100)
In terms of composition, the crystal structure has a columnar grain structure with the C axis of the HCP structure oriented in the vertical direction, and has magnetic crystalline anisotropy.
It is characterized by forming a film in which ku⊥ is larger than the perpendicular demagnetizing field 2πMs ² .

Next, examples of the present invention will be described.

FIG. 1 shows a vacuum evaporation apparatus for carrying out the present invention, in which a rotary cooling can 2 and an electron beam evaporation source 3 are provided directly below the container 1, which is connected to a vacuum pump on one side, and an electron beam evaporation source 3 is provided above the container 1. Unwinding roller 4 on both sides
and a take-up roller 5, and a non-magnetic base material, for example, a roll-shaped material, is wound around the roller 4.
The PET tape base material a was rotated around the circumferential surface of the cooling can 2 along with the rotation of the cooling can 2 so as to be wound around the roller 5. According to the invention, a supply pipe 6 for introducing oxygen into the container 1 is provided. In the illustrated example, this is a long one that opens near the a side of the running tape. 7 shows a rod-mounted plate placed horizontally leaving the bottom surface of the cooling can 2 facing directly above the evaporation source, thereby preventing the evaporation of Co from the evaporation source 3.
The atoms and Ni atoms were incidentally deposited substantially perpendicularly to the a-plane of the tape substrate.

Using this device, first evacuate the inside of the container 1 to below 1×10 ^-5 Torr, and then
An alloy or a metal mixed with a predetermined ratio of Co and Ni is evaporated at a constant rate by electron beam heating, while
By introducing O ₂ gas through the supply pipe 6, vertical vapor deposition is performed on the a side of the tape base material running at a constant speed,
A deposited film having a composition of Co-Ni-O is obtained, but in this case, the amount of O ₂ gas introduced is varied so as to have various partial pressures, or the amount of O ₂ gas to be evaporated is changed. Magnetic recording bodies having deposited Co--Ni--O films with various composition ratios were manufactured by varying the ratio of Co and Ni. The film thickness was set in the range of 1000 Å to 10000 Å by varying the running speed of the tape base material. The relationship between various magnetic films having different composition ratios of the Co--Ni--O ternary components obtained in this manner and their magnetic properties was examined. The results are shown in Figure 2.
It was as shown in FIGS. 3 and 4. As is clear from Figure 2, as the O component increases, the ratio Hc⊥/Hc of the coercive force Hc⊥ in the vertical direction to the coercive force Hc in the parallel direction increases, and the diagonal lines in the figure indicate the O content of 15 at% or more. In the enclosed area, Hc⊥/Hc>1. The residual magnetic flux density also increases as the O component increases, as shown in Figure 3.
In the area surrounded by diagonal lines in the above figure, Br⊥／Br＞
It becomes 1. However, when the O component is 50 at% or more, the saturation magnetization becomes zero in all cases, as shown in FIG. From the above results, Co _x Ni _y O _z (x, y, z
is at%, 0<y<40, 15<z<50, x+y+z
It can be seen that a perpendicularly magnetized film can be obtained in the region of =100). FIG. 5 shows a hysteresis curve of a typical perpendicular magnetization film of the present invention having a composition of Co ₆₃ Ni ₇ O ₃₀ , and it can be seen that the film is a perfect perpendicular magnetization film. In the case shown in Figure 5, by vacuum melting
A Co-Ni alloy made with a composition ratio of Co and Ni of 9:1 was used as the evaporation material, and 150 SCCM of O ₂ gas was flowed into the evacuated container to increase the O ₂ introduction partial pressure to 6 ×
After adjusting the temperature to 10 ^-5 Torr, the evaporated material was evaporated at an evaporation rate of 45000 Å/min using a 12 KW electron beam evaporation source, and a water-cooled 12 μm thick PET film was fed at a feed rate of 1.0 m/min. to the base material
A perpendicularly magnetized film was fabricated by substantially vertically incident evaporation deposition at 1800 Å. Thus, the O composition z is 15
It must be in the range of ~50 at%, and a perpendicular magnetization film can be obtained when the Ni composition y is in the range of 0 to 40 at% and the Co composition x is in the remaining range. If the Ni composition y is 40 at% or more, the crystal structure of the precipitated metal particles becomes an FCC structure, the crystal magnetic anisotropy is extremely reduced, and a perpendicularly magnetized film cannot be obtained. Further, the perpendicular magnetization film of the present invention to which Ni is added has an additional feature of excellent corrosion resistance. Further, in the perpendicularly magnetized film of the present invention, the value of the perpendicular coercive force Hc⊥ is about 400 to 1000 Oe,
This is the best value for a perpendicular magnetic recording medium.

In addition, when changing the evaporation rate of Co-Ni,
In order to obtain a film having the composition range described above, it is necessary to change the amount of O ₂ gas introduced. This relationship is based on
Since it is approximately proportional to the incidence frequency of Co and Ni atoms and O atoms, when the amount of evaporation of Co-Ni increases, it is necessary to increase the O ₂ partial pressure as well.

According to the present invention, there is no need to heat the base material,
A perpendicularly magnetized film can be obtained by actively cooling with a water-cooling can or by leaving it unheated at room temperature.
As in the manufacturing method of perpendicular magnetization film, the base material is heated to 200 to 300℃.
This is advantageous compared to those that require heating to
There is no need to use expensive heat-resistant materials such as polyimide film as the base material, and it is possible to use inexpensive plastic films such as PET tape, so the materials for the equipment can be freely selected. or,
Even if the base material is heated, the desired perpendicularly magnetized film of the present invention can be obtained.

Furthermore, according to the present invention, since the vapor pressures of Co and Ni are almost equal, even if a Co-Ni alloy with the desired composition is made in advance and evaporated from a single evaporation source, the composition of the deposited film will hardly change. A predetermined percentage of Co−
Since Ni vapor deposition can be obtained, if the amount of O ₂ gas introduced is kept at a predetermined constant amount, a perpendicularly magnetized film of the present invention with a predetermined uniformity can be produced for an extremely long time, and compared to the conventional Co-Cr
The drawbacks of producing films with non-uniform component compositions, such as the production of perpendicularly magnetized films that evaporate components with significantly different vapor pressures, are eliminated. Furthermore, the perpendicular magnetization film of the present invention does not cause curling even when formed on a PCT substrate or a floppy disk substrate.
Compared to Co--Cr based perpendicular magnetic recording bodies, which cause very severe curling, this method is extremely easy to manufacture and provides a good product.

The reason why the Co--Ni--O thin film of the present invention exhibits perpendicular magnetization characteristics is not fully clear, but it is thought to be as follows.

That is, when Co and Ni atoms are incident perpendicularly to the base material and deposited, a thin film having a columnar grain structure in which the C axis of the HCP structure is oriented in the vertical direction is created, as described above. At this time, simultaneously inside the vacuum container
When O ₂ gas is introduced, some of the deposited Co and Ni atoms are oxidized and CoO, NiO, or similar oxides are precipitated simultaneously, and the surroundings of the Co-Ni particles are covered with the non-ferromagnetic oxide. It is thought that it has an ivy membrane structure. Therefore, this Co-Ni columnar particle has shape magnetic anisotropy in addition to crystal magnetic anisotropy.
Improved perpendicular magnetic anisotropy. When the film structure is partially oxidized as described above, the average saturation oxidation value of the entire film decreases, so it is thought that the condition Ku⊥≧2πMs ² is satisfied and perpendicular magnetization characteristics are obtained. Further, the particle size of the Co--Ni columnar particles is thought to be approximately several hundred Å to several thousand Å, and since they are in the form of metal particles, a high coercive force can be obtained.

A trace amount of other elements may be mixed into the above-mentioned predetermined Co--Ni--O perpendicular magnetization film of the present invention. In addition, elements that dissolve in Co and do not harm the HCP structure, such as Cr, V, Mo, W, Rh, Ti,
There is no problem with the inclusion of trace amounts of Re, etc.

In the perpendicular magnetic recording method, permalloy, Fe, Co,
According to the present invention, if a thin film of a magnetic material exhibiting relatively soft magnetism and high saturation magnetization such as a Co-Zr amorphous film is interposed, the recording current can be reduced and the reproduction output can be increased. , after forming a soft magnetic thin film layer on the non-magnetic base material surface, on the top surface of the thin film layer,
For example, according to the example above, a given Co-Ni-O
By forming a perpendicularly magnetized film having the same composition, the perpendicular magnetic recording body of the present invention including the soft magnetic thin film layer can be manufactured.

When applied to a floppy disk, the present invention also provides a perpendicular magnetization film having the predetermined Co-Ni-O composition formed on one or both sides of the base material, either directly or with the soft magnetic thin film layer interposed therebetween. The perpendicular magnetic recording body of the invention may also be manufactured.

Thus, according to the present invention, Co _x Ni _y O _z
(x, y, z are at%, 0<y<40, 15<z
<50, x+y+z=100)
0 composition, the crystal structure is vertically HCP structure C
Columnar grain structure with oriented axis and crystal magnetic anisotropy
Since we have formed a film with ku⊥ larger than the perpendicular demagnetizing field 2πMs ² , we can obtain a perpendicular magnetic recording medium with a good perpendicular magnetization film. Co _and Ni atoms are deposited substantially perpendicularly onto the surface of the soft magnetic thin film layer formed on the surface of the soft _{magnetic thin film} layer. vertically
It has a columnar grain structure with the C axis of the HCP structure oriented, and the magnetocrystalline anisotropy Ku⊥ is perpendicular to the demagnetizing field 2πMs ²
Unlike the conventional production of Co-Cr perpendicularly magnetized films, we have formed a film that is larger than the above, so a uniform perpendicularly magnetized film can be produced over a long period of time, allowing efficient mass production, and also by heating the base material. There is no need to do this, and there is an effect that a good perpendicular magnetization film can be obtained even if an inexpensive base material is used at room temperature.

[Brief explanation of drawings]

FIG. 1 shows one of the apparatuses for carrying out the manufacturing method of the present invention.
The cross-sectional side view of the example, Figures 2, 3, and 4 are diagrams showing the relationship between various Co-Ni-O compositions and magnetic properties, respectively, and Figure 2 is a diagram showing the value of Hc⊥/Hc. , Figure 3 shows the value of Br⊥/Br, Figure 4 shows the value of Br⊥/Br.
The figure shows the value of saturation magnetization Ms, and FIG. 5 shows a hysteresis curve diagram of an example of the perpendicular magnetization film of the present invention. DESCRIPTION OF SYMBOLS 1... Container, a... Tape base material, 3... Evaporation source, b... Evaporation material Co, Ni, 4, 5... Roller, 6... Oxygen gas supply pipe, 7... Anti-adhesion plate.

Claims (1)

[Claims] 1 Co _x Ni _y O _z (where x, y, and z are at%, 0<
y<40, 15<z<50, x+y+z=100), the crystal structure has a columnar grain structure with the C axis of the HCP structure oriented in the vertical direction, and the crystalline magnetic anisotropy ku ⊥ is the vertical diamagnetic field
A perpendicular magnetic recording medium formed by forming a film larger than 2πMs ² . 2 Co and Ni atoms are deposited substantially perpendicularly on the surface of the nonmagnetic base material or on the surface of a soft magnetic thin film layer previously formed on that surface, and at the same time O ₂ gas is introduced to form Co _x Ni _y O _z (x, y, z are at%, 0
<y<40, 15<z<50, x+y+z=100), the crystal structure has a columnar grain structure with the C-axis of the HCP structure oriented in the vertical direction, and has magnetic crystalline anisotropy. ku⊥ is the vertical diamagnetic field
A method for manufacturing a perpendicular magnetic recording medium, characterized by forming a film larger than 2πMs ² .