JPS6177126A - Magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve magnetic characteristic and productivity by forming the magnetic film of a Co-Cr alloy contg. slightly W on a base body to a specified film thickness. CONSTITUTION:The magnetic recording constituted by forming the magnetic film consisting of the Co-Cr alloy contg. just about <=1.9atom% W on the base body has the improved c-axis orientability of the pulverous alloy crystal, im proved vertical magnetic anisotropy and the improved magnetic characteristics such as saturation magnetization. The excellent magnetic recording medium is thus obtd. by the thin vertically magnetizable film. The thickness of the vertical magnetizable film is made about 0.1-0.25mum to form the magnetic film having the excellent vertical magnetic anisotropy and substantial reproduced output. The formation of the magnetic film by a PVD means such as sputtering is executed in the shorter time by which the production efficiency is improved, the less material is required and the cost is reduced. The saturation magnetiza tion exceeds 300emu/cc which is a measure for practicability and HCL is large.

Description

[Detailed description of the invention] [Industrial application field] The present invention particularly relates to perpendicular magnetic recording media.

[Prior art and its problems]

For example, in recording and reproducing devices for audio or video, or storage devices for computers, etc., a magnetic recording medium is used in which a magnetic layer coating is provided on a magnetic recording medium, and a ring-shaped magnetic head is used to A horizontal magnetic recording method is used in which magnetization is directed in the horizontal direction.

However, in the case of recording using this horizontal magnetic recording method, as the wavelength of the recording signal becomes shorter, that is, as the recording density increases, the demagnetizing field within the medium increases, causing attenuation and rotation of the residual magnetization, which causes playback. The horizontal magnetic recording method cannot cope with higher densities since the output will be significantly reduced.

Therefore, recently, perpendicular magnetic recording has been attracting attention as a new recording method to replace the above-mentioned horizontal magnetic recording which records within the plane of the medium.

This perpendicular magnetic recording method uses a magnetic recording medium in which the easily magnetized glaze is in the normal direction to the film surface, and configures the recording magnetization mode in the direction perpendicular to the film surface, so that the recording signal has a short wavelength. This is because the demagnetizing field within the medium becomes smaller as the density increases, making it suitable for higher densities.

As such a perpendicular magnetic recording medium, an lpm-thick magnetic film has been proposed, for example, containing chromium in cobalt and further containing 2 to 10 atoms of tungsten, for example, 4.5 atoms, as a third component. (/l!i-No. 1987-73913).

However, due to the thick magnetic layer, this magnetic recording medium is prone to siflux, and does not fit well with the ring-type magnetic head, resulting in poor playback performance, and the manufacturing efficiency of the magnetic recording medium is also poor. It has been found that there are drawbacks such as (it takes too much time to form a film) and that it requires a large amount of magnetic material, resulting in high cost.

It has also been found that a desirable perpendicular magnetic recording medium cannot be obtained simply by reducing the thickness of the magnetic film.

[Disclosure of the invention]

The present inventor has discovered that a magnetic recording medium in which a magnetic film of a Co-Cr alloy containing less than about 1.9 atoms of W is formed on a substrate can be used even if the film thickness is as thin as, for example, about 0.2 μm. , the saturation magnetization is large, the perpendicular coercive force is large, the perpendicular anisotropy is high, and its magnetic properties are excellent.The thickness of the duty magnetization film is small, making it difficult for cracks to occur, and it is highly flexible. It has been found that the contact with the magnetic head is good, and therefore the reproduction quality is also improved accordingly.Moreover, there is no ambiguity in the use of the magnetic recording material, and the productivity can be improved and the cost can be reduced accordingly.

In other words, by adding about 1.9 atoms or less of W, preferably about 0.5 to 1.5 atoms, to an alloy containing Co and C, it is possible to add W to an alloy containing Co and C. They discovered that the axial orientation is improved, the perpendicular anisotropy is increased, and the magnetic properties such as saturation magnetization are also good, making it possible to provide an excellent magnetic recording material with a thin perpendicularly magnetized film. An excellent perpendicular magnetization film can be obtained by adding about 1.9 atoms or less, especially about 0.5 to 1.5 atoms, but if W is included in excess of 2 atoms, The characteristics of the perpendicular magnetization film deteriorate, especially when the thickness of the perpendicular magnetization film is approximately 0.1 to 0.
．． It has been found that when the thickness is as thin as 25 μm, it cannot actually be used as a perpendicular magnetic recording medium.

It is preferable that the content of Cr in the perpendicular magnetization 11 is about 5 to 20 atoms, that is, if the Cr content is more than 20 at%, it may be less than 8 or 5 atoms. has extremely desirable magnetic properties.<<,
In particular, when the thickness of the 1U magnetized film is as thin as about 0.1 to 0.25 μm, the magnetic properties are not very desirable.

The thicker the perpendicularly magnetized film made of the Co-Cr alloy containing W, the higher the Niu output value, but the thicker it is, the less flexible the magnetic recording medium is and the contact with the magnetic head is lower. However, since the reproduction condition will not be good, the thickness of the perpendicular magnetization film should be about 0.1 to αμm (
It is essential. Similarly, even if the thickness of the perpendicularly magnetized film is reduced in this way, it will contain only about 1.9 atoms or less of W, especially about 0.
Magnetism +11:'4 made of a Co-Cr alloy microcrystalline film containing 5 to 1.5 atoms has excellent superposed magnetic anisotropy,
In addition, the playback output is light and magnetic 1! ! , f can be formed using a PVD process such as sputtering in a short time, which improves the manufacturing rate and improves the f of the material.
It can be done at low cost because it requires less il.

However, this method is not limited to the 3-component system of Co-Cr-W, but also includes 4 impurities, 84 o,
It is okay to use B for Ta, Nb, etc.
O vacuum irreducible I X 10-' Torr, flune f1j
Using an RF magnetron sputtering device under the conditions of xFEIXIO-3 Torr, input power of 1000 W, and distance between target substrates of 110 fl, the perpendicular magnetization film composition and film thickness of a perpendicular magnetization film of Co-Cr-W alloy microcrystals were determined according to the example. 1
In those of (co812CrI68)9(sWIILs
and 0.18 μm, and in Example 2 (Co
5a2Cr 118 ) to 9! W as and 0.1
9 μm, and in Example 3 (008U2C1t
ag) +1 & 7 W 1. s and Q are 29 μm.

[Comparative Examples 1 and 2] A 0.28 μm thick perpendicularly magnetized film (film composition Co so
Crza, Comparative Example 1) and a perpendicularly magnetized film with a thickness Q of 19 μm (film composition (Co51x Cr tag) *
v, 3Wtt, Comparative Example 2) was constructed.

〔Characteristic〕

The reproduction waveforms when reproduced by the residual magnetization Woring head recorded on the magnetic recording media of Examples 1 to 3 above are as follows.
+, 9 to yln shown in FIG. 3, and the reproduced waveform is bimodal pulse-like, indicating that the device of this example is a perpendicular magnetic recording system.

In other words, when the residual bacteria magnetization component is only a horizontal component, the reproduced waveform is a unimodal pulse, whereas as the vertical component increases, the reproduced waveform becomes a bimodal pulse. It can be seen that as the W content increases, the bimodal pulse ratio increases, and therefore, as the W content increases, the tunic component increases.

Moreover, the magnetic recording lt of the above Examples 1 to 3 and Comparative Example 1.2
'l: Saturation magnetization Ms of the body, vertical coercive force HCL %
Horizontal coercive force Hc t・, horizontal magnetization curve squareness ratio Rst・, rocking curve half width Δθso dl
The result is 71 edges shown in the table.

In other words, the saturation magnetization of this example exceeds 300 emu/cc, which is currently considered as a practical guideline, the HCL is strong, and the value of Δθ1 is small (crystal orientation (Improved performance), it can be seen that it is excellent as a perpendicular magnetic recording medium.

Furthermore, when the wavelength characteristics of Example fil 1 and Comparative Example 1 were measured, they were as shown in Figure 4, and although the film thickness of Example fil 1 was approximately 7, On the contrary, the reproduction output of the sample increased with the addition of W, indicating that it is excellent in high-density recording.

The above Example 17 has a perpendicularly magnetized film with a film thickness of about 0.2 μm, which shows excellent magnetic properties despite the fact that the thickness of the perpendicularly magnetized film is thin. It is highly flexible, makes good contact with the magnetic head, and has good playback characteristics.

〔effect〕

An excellent perpendicular magnetic recording medium, especially perpendicular magnetization even if the thickness is thin! The characteristics are good, and since the perpendicular magnetization film is thin, the productivity is improved, the material cost is low, it can be manufactured at low cost, and the reproduction quality is also excellent.

4. I'! , 1. Brief Description of Figures 1 to 4 are graphs showing the characteristics of the magnetic recording body 919.

Claims (1)

[Claims] 1. A magnetic recording medium characterized in that a magnetic film of a Co--Cr alloy containing about 1.9 atomic % or less of W is formed on a substrate to a thickness of about 0.1 to 0.25 μm.