JPS58165306A - Vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve a high frequency characteristic by using a vertical magnetic film which comprises a magnetic alloy with saturated magnetization not less than a specific value and preferentially amorphous property. CONSTITUTION:A vertical magnetic recording medium is formed of a vertical magnetic film which comprises a magnetic alloy with saturated magnetization value not less than 100emu/cc and preferentially amorphous property. The preferentially amorphous magnetic alloy may be compossed of such an alloy as containing 50-90 atom% of at least one element selected from a group of Fe, Co and Ni and 10-40 atom% of at least one element selected from a group of La, Ce, Pn, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu. By so doing, a high frequency characteristic is improved in the present examples 1-3 as compared with the prior art using a Co-Cr thin film, as seen from the figure.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic recording medium used in a perpendicular magnetic recording system.

Perpendicular magnetic recording is a magnetic recording medium layer (perpendicular magnetization film) that has an axis of easy magnetization perpendicular to the running direction of a magnetic recording medium such as a magnetic tape or magnetic disk, that is, in the thickness direction of the magnetic recording medium. is provided on the surface of the magnetic recording medium, and a magnetic head for perpendicular magnetic recording that generates a strong magnetization distribution in the thickness direction of the magnetic recording medium; magnetizes the magnetic recording medium in the thickness direction, and This is so that the magnetization of the magnetic medium layer remains. In this way, magnetic: °
) If there is a residual magnetization distribution in the thickness direction of the recording medium.

'I High-density recording with less self-demagnetizing field and less loss becomes possible (see, for example, Japanese Patent Laid-Open No. 134706/1983).

Tatsu Iwasaki (Tohoku University) has shown that the Co-Cr alloy film is the most perpendicularly magnetized film (IEEE Trans, Mag, MAG14).
('78)849).

The present inventors also fabricated a Co-Cr thin film by sputtering on a glass substrate or a Co-Cr thin film fabricated by sputtering on a high permeability magnetic thin film provided on a glass substrate.
Recording and reproduction are performed using a ring-shaped magnetic head on a perpendicular magnetic recording medium made of a thin film, and the recording density I) so, which provides half the output of low-density recording, is 70 KBPI and 80 KBPI, respectively, twice that of in-plane recording. (The Co-Cr film was presented at the 1986 National Conference of the Institute of Electronics and Communication Engineers, Semiconductor and Materials Division,
The one consisting of a Co-Cr film and a high permeability magnetic layer has not yet been published).

The present inventors conducted various experiments on a perpendicularly magnetized film capable of higher density recording than the Co-Cr alloy thin film described above.

As a result of the study, it was found that by using a perpendicularly magnetized film made of a predominantly amorphous alloy with a saturation magnetization of 100 emu/cc or more in place of the Co", Cr alloy thin film, I)s .

The headline shows that it is possible to extend the amount of data to more than 200KBPI.

The reason why I) so in the case of using a Co--Cr alloy thin film is smaller than that in the case of using the above-mentioned alloy which is predominantly amorphous.

This is because the grain size of the Co-Cr alloy thin film is approximately 0.15 μm.

This is considered to be because the reproduction output decreases when the recording bit length becomes 0.4 μm or less.

Note that when the saturation magnetization of the perpendicularly magnetized film made of the predominantly amorphous magnetic alloy is 100 emu/cc or less,
The reproduction output becomes too small and is not suitable for practical use.

The predominantly amorphous magnetic alloy is Fe.

60 to 90 atomic% of at least one element selected from the group consisting of Co, Ni, La, Ce, Pr, Nd
, Sm, Eu, Gd, Tb.

An alloy containing 10 to 40 atoms of at least one element selected from the group consisting of Dy, Ho, Er, Tm, Yb, and Lu is suitable. An alloy consisting of elements outside the above range will not form a perpendicularly magnetized film.

2. As is well known, a perpendicular magnetic recording medium in which a high permeability magnetic layer is provided under a perpendicular magnetization film requires less current for recording than a perpendicular magnetic recording medium that does not have a high permeability magnetic layer. 2 frequency characteristics are also good.

If a thin film made of a predominantly amorphous alloy is used as the high permeability magnetic layer provided below the perpendicular magnetization film, a perpendicular magnetic recording medium with better frequency characteristics than the well-known permalloy thin film can be obtained. However, permalloy thin films are also used.

Note that there is a thickness α2 between the perpendicular magnetization film and the high permeability magnetic layer.
By providing a non-magnetic layer with a thickness of μm or less.

It is possible to obtain a perpendicular magnetic recording medium with even better frequency characteristics than a perpendicular magnetic recording medium without this nonmagnetic layer. The above-mentioned non-magnetic layer is for eliminating the interaction between the perpendicular magnetization film and the high permeability magnetic layer, and its thickness needs to be several tens of inches or more, but the thickness is 0.2
If the diameter exceeds μm, the effect of the high permeability magnetic layer becomes smaller.

The current required for recording increases and the frequency characteristics also deteriorate.

The material constituting the high permeability magnetic layer is as follows.

Any high permeability alloy that is predominantly amorphous can be used. Currently, two kinds of secondary alloys are known as such materials, and it goes without saying that any of them can be used.

That is, (1) 65 to 95 at% of at least one element selected from the group consisting of Fe, Co, and Ni;
Cr, Mo, v, w.

The composition contains 30 atoms or less of at least one element selected from the group consisting of Nb, and 5 to 35 atoms of at least one element selected from the group consisting of Ti, Zr, and Hf.

Alternatively, (2) 70 to 88 at% of at least one element selected from the group consisting of Fe, Co, and Ni, Mo,
Cr, W, V.

Sm, Gd, Eu, Tb, Dy, Ho, E
r, Nd, Pr, Ce, La, Tm.

It is known that the composition contains 20 atoms or less of at least one element selected from the group consisting of Yb and Lu, and 12 to 30 atoms of at least one element selected from the group consisting of B, C, Si, and A4P. , both are used. be able to.

In the alloy having the composition (1) above, Fe, Co
, Low Ni:,.

If at least one species has more than 95 atoms, then

The alloy is no longer amorphous, and if it has less than 65 atoms,
Because the saturation magnetic flux density Bs of the alloy becomes too small (B
s(2KG), saturation occurs due to the upper perpendicular magnetization film, and the performance as a high magnetic permeability film deteriorates. Cr.

When at least one of Mo, V, W, and Nb exceeds 30 atoms, Bs of the alloy thin film becomes too small. Furthermore, when at least one of Ti, Zr, and If exceeds 65 atoms, Bs becomes too small, and when it is less than 5 atoms, the alloy thin film is no longer a predominantly amorphous alloy thin film. Either case is not preferable.

Further, in the alloy having the composition (2) above, Fe,
Co.

When at least one type of Ni exceeds 88 atoms,
The alloy thin film is no longer a predominantly amorphous alloy thin film,
If it is less than 70 atoms, Bs becomes too small. Cr, Mo, V, W, Nb, Sm, G
d, Eu, Tb; Dy, Ho, Er, Nd, Pr, C
At least one of e, La, Tm, Yb, and Lu is 20
If it exceeds atomic Q, Bs becomes too small - again. When at least one of B, C, Si, and A4P exceeds 60'1 element/1 child ratio and is less than 12 atoms, the alloy thin film is predominantly an amorphous alloy. This does not result in a thin film, which is not preferable in either case.

Note that the magnetic permeability of the high magnetic permeability magnetic layer in the present invention is 10.
More preferably, it is 100 or more. When the magnetic permeability of the magnetic layer is 10 or less, a magnetic head for perpendicular magnetic recording is used.

When recording on a perpendicular magnetic recording medium, the recording current increases, making it useless as a high magnetic permeability film.

In addition, the saturation magnetic flux density Bs of the high permeability magnetic layer in the present invention is desirably larger than the Bs of the upper perpendicularly magnetized film.9 For example, when a Tb15Fe85 alloy is used as the perpendicularly magnetized film, the high permeability magnetic layer It is desirable that Bs of 2 kg or more.

The substrate material constituting the substrate on which the high permeability magnetic layer made of a predominantly amorphous magnetic alloy or the perpendicularly magnetized film is deposited may be those conventionally used in magnetic recording media. I can do it, but 9 is normal.

Glass, A7. Polyimide resin material and polyester resin material are used. Further, an alumina layer, a coupling material layer, etc. may be provided on the surface of these materials.

Further, the substrate may be in the form of a plate or a flexible tape.

As is well known, the thickness of the perpendicular magnetization film is O,OS ~ 5 μm.
The thickness of the high permeability magnetic layer made of a predominantly amorphous alloy is 0.05 μm or more, preferably 0.5 μm or more. If the thickness of the high permeability magnetic layer is thinner than the above, it is not preferable because the recording current needs to be reduced.

Note that in the present invention, a predominantly amorphous alloy refers to an alloy in which no specific peak is observed in a normal X-ray diffraction pattern.

The present invention will be explained in detail below using examples.

Example 1゜T was deposited on a glass substrate and an At substrate by the vine method.
A perpendicular magnetic recording medium is created by depositing a 0.5 μm thick amorphous magnetic alloy thin film (perpendicular magnetization film) made of b15Fe65.
Created. Recording was performed on this perpendicular magnetic recording medium using a perpendicular magnetic recording medium head as shown in FIG. 1, and reproduction was performed using a ring-type magnetic head with a gap length of 0.05 μm. In FIG. 1, 1 is a perpendicular magnetic recording medium;
2 is a main magnetic pole made of a rectangular high permeability magnetic thin plate, and 3 is an auxiliary magnetic pole which is sufficiently larger than the main magnetic pole 2 and has a wire wound thereon.

The current required for recording with this magnetic head was 200 mA.

For comparison, FIG. 1 shows two types of conventional perpendicular magnetic recording media obtained by providing a high permeability magnetic layer on the substrate and further depositing a Co-Cr thin film on top of the above-mentioned substrate. The results of recording and reproduction performed using the magnetic head are also shown.

Example 2゜Co, Mo, and Zr powders in an atomic ratio of 80:
Using a disk prepared by mixing and sintering the mixture at a ratio of 9.5:10.5 as a target, a highly transparent thin film of an amorphous alloy with a thickness of 1 μm was sputtered onto the glass substrate and A/ substrate. A magnetic material layer was formed. Then, r'j Tbl5F is deposited on this high permeability magnetic layer by sputtering.
An amorphous alloy thin film with a thickness of 0.5 μm consisting of e5s (:[
・Vertical magnetized film) was deposited. This is how you get it, -
Recording was performed on a magnetic recording medium using the two types of magnetic fields described in Example 1.

Played. In this example, the current required for recording was 130 mA. The relationship between recording density and reproduction output obtained as a result is shown in Figure 1.

Example & In Example 2, a perpendicular magnetic recording medium was obtained by providing a 5i02 film with a thickness of 100 Å between the high permeability magnetic layer and the perpendicular magnetization film by sputtering. Recording was performed on this perpendicular magnetic recording medium using the two types of magnetic heads described in Example 1.
Played. The relationship between the recording density and reproduction output obtained as a result is shown in FIG.

From FIG. 1, D5° when using the perpendicular magnetic recording medium of Example 1.2.5 is 190.200 and 210 KBPI, respectively, and D5° when using the Co-Cr thin film is 70 KBPI. It turns out that it is much larger.

Note that in FIG. 1, the reason why the output becomes almost zero at about 250 KBPI is thought to be mainly due to the gap length of the head1. In other words, it is considered that if magnetic l1lbf and rad with smaller gap lengths are used, nso in each of the above embodiments will become even larger.

Furthermore, the amorphous nature of each of the thin films of Examples 1 to 5 was confirmed by X-ray diffraction halo patterns.

As detailed above, it can be seen that when an amorphous alloy thin film is used as the perpendicular magnetization film, a perpendicular magnetic recording medium with better high frequency characteristics can be obtained than when a conventional Co--Cr thin film is used.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a magnetic head for perpendicular magnetic recording used in the present invention, and FIG. 2 is an explanatory diagram of a perpendicular magnetic recording medium (
FIG. 4 is a curve diagram showing the relationship between recording density and reproduction output obtained by recording using a head with a perpendicular magnetic recording medium and reproducing using a ring-type magnetic head with a gap length of 0.05 μm. In fig. 1... Perpendicular magnetic recording medium 2... Main magnetic pole 3...
Auxiliary Magnetic Pole Representative Patent Attorney Junnosuke Nakamura 1 Illustrations 2 Illustrations 4#-zYukai 9PI) Continued from page 1 0 Author: Toshio Niihara Inside the Central Research Laboratory, Hitachi, Ltd., 280 Higashi-Koigakubo-chome, Kokubunji City

Claims (1)

[Scope of Claims] 1. A perpendicular magnetic recording medium characterized by having a perpendicular magnetization film made of a predominantly amorphous magnetic alloy having a saturation magnetization of 100 emu/cc or more. 2. The perpendicular magnetic recording medium according to claim 1, wherein the predominantly amorphous magnetic alloy is Fe, Co,
60 to 90 at% of at least one element selected from the group consisting of Ni, La, Ce, Pr, Nd,
Sm. Eu, Gd, Tb, Dy, Ho, Er, T
A perpendicular magnetic recording medium characterized in that it is an alloy containing 10 to 40 atoms of at least one element selected from the group consisting of m, Yb, and Lu. 5. A perpendicular magnetization film made of a predominantly amorphous magnetic alloy with a saturation magnetization of 100 emu/cc or more, and a high permeability magnetic layer provided on the back surface of the perpendicular magnetization film, A perpendicular magnetic recording medium characterized in that the high permeability magnetic layer is predominantly an amorphous magnetic alloy or a permalloy alloy. 4. The perpendicular magnetic recording medium according to claim 3, wherein the high permeability magnetic layer is made of Fe, Co. At least one element selected from the group consisting of Ni, 65~
95 atomic %, at least one element selected from the group consisting of Cr, Mo, V, W, and Nb in an amount of 55 atoms or less, Ti. A perpendicular magnetic recording medium comprising a predominantly amorphous magnetic alloy containing 5 to 35 atoms of at least one element selected from the group consisting of Zr and Hf. 5. The perpendicular magnetic recording medium according to claim 3, wherein the high permeability magnetic layer is made of Fe, Co. At least one element selected from the group consisting of Ni
88 atomic%, Cr, Mo, V, W, Nb,
Sm, Gd, Eu, Th. Dy, Ho, Er, Nd, Pr, Ce, L
a, Tm, Yb, Lu at least one element selected from the group consisting of 20 atoms or less, B, C, Si
A perpendicular magnetic recording medium comprising a predominantly amorphous magnetic alloy containing 12 to 50 atoms of at least one element selected from the group consisting of , At, and P. 6. The perpendicular magnetic recording medium according to claim 3, characterized in that a nonmagnetic layer with a thickness of 0.2 μm or less is provided between the perpendicular magnetization film and the high permeability magnetic layer. Perpendicular magnetic recording medium.