JPS6052920A - Vertically magnetized recording medium - Google Patents

Abstract

PURPOSE:To obtain an excellent recording density-reproduced output characteristic by forming a titled medium which has a magnetic recording layer provided with an axis of easy magnetization in the thickness direction and consisting the magnetic recording layer of two magnetic layers provided with prescribed coercive force characteristics. CONSTITUTION:A high permeability layer 3 is provided on a base plate 2 consisting of a nonmagnetic layer and the 1st magnetic layer 11 and 2nd magnetic layer 12 each consisting of a thin alloy film composed of cobalt and chromium are further providee thereon. The thin alloy films are composed in the range where chromium content is 15-20wt% and vertical anisotropy is not lost. The layer 11 has the coercive force in the thickness direction larger than the coercive force in the in-plane direction and the medium is constituted by providing the 2nd magnetic layer 12 having the coercive force in the in-plane direction larger than the coercive force in the thickness direction on the layer 11.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a perpendicular magnetization recording medium having a magnetic recording layer having an axis of easy magnetization in a direction perpendicular to a substrate surface (thickness direction).

Conventional structure and problems Traditionally, the magnetic recording method is a horizontal magnetization recording method that uses a ring head and a horizontal magnetization recording medium that has a magnetic layer that is magnetized in a direction parallel to the substrate surface (in-plane direction). Although the Lord was
In recent years, in order to cope with the increasing density of magnetic recording, a perpendicular magnetization recording medium with an axis of easy magnetization perpendicular to the substrate surface (thickness direction) and a perpendicular recording/reproducing magnetic head (hereinafter referred to as a perpendicular head) have been used. A perpendicular magnetization recording method has been proposed and much research has been conducted.

In the perpendicular magnetization recording method, unlike the horizontal magnetization recording method,
As the recording density increases, the demagnetizing effect becomes smaller, essentially enabling higher recording densities. Furthermore, in perpendicular magnetization recording,
By providing a layer with high magnetic permeability between the perpendicular magnetization layer and the substrate, it is possible to greatly improve recording and reproducing sensitivity.

FIG. 1 shows a cross-sectional view of the perpendicular magnetization recording medium consisting of the two layers described above. In the figure, a perpendicular magnetization recording medium 1 includes a substrate 2 made of a non-magnetic material such as glass, ceramic, or polymer film, and a high magnetic permeability layer 3 made of a Fe-Ni alloy or the like.
It is composed of a perpendicular magnetization layer 4 made of a Co-0 layer alloy or the like and having an easy axis of magnetization perpendicularly.

FIG. 2 does not show the structure of a magnetic head (perpendicular head) that performs recording and reproduction perpendicularly to a perpendicularly magnetized recording medium. Reference numeral 1 denotes a perpendicular magnetization recording medium, which includes a substrate 2 made of a non-magnetic material as described above. High permeability layer 3. It is composed of a perpendicular magnetization layer 4. A main magnetic pole 5 and an auxiliary magnetic pole 8 are provided to sandwich the perpendicular magnetization recording medium 1, forming a perpendicular head. Main magnetic pole 5
consists of a high magnetic permeability thin film 6 made of permalloy or the like and a supporting substrate 7 that supports it, and the auxiliary magnetic pole 8 is made up of a coil 9 wound around a high magnetic permeability block 1o of ferrite or the like. The high magnetic permeability block 10 is magnetized in accordance with the information signal applied to the coil 9, and the generated magnetic flux magnetizes the high magnetic permeability thin film 6 of the main magnetic pole 6, and this magnetization is written into the perpendicular magnetic layer 4. Reproduction is performed by a process completely opposite to this writing process, and the high magnetic permeability thin film 6. High permeability block 1
It passes through the coil 9 and is read out as an electrical signal.

Although such a thread recording/reproducing method is common in perpendicular magnetization recording, a one-sided recording/reproducing head in which a coil 9 is provided on the main pole 5 has also been proposed, and the recording/reproducing characteristics are essentially the same.

In the above perpendicular recording/reproduction method, the thickness t of the perpendicular magnetic layer 4 is relatively thick (0.5 μm) and relatively thin (0.5 μm).
FIG. 3 shows an example of the reproduction output with respect to the recording density of the medium (2 μm). Even in the perpendicular magnetization recording method, the output decreases with high density, and in addition, media with a thick perpendicular magnetization layer,
Although the reproduction output is high at low density, the reproduction output decreases significantly at high density.

Purpose of the Invention The present invention was developed in order to eliminate such drawbacks of the conventional technology, and its purpose is to obtain high reproduction output from low to high recording densities even in media with relatively thick perpendicular magnetization layers. An object of the present invention is to provide a perpendicular magnetization recording medium.

Composition of the Invention The perpendicular magnetization recording medium of the present invention has at least a magnetic recording layer having an axis of easy magnetization in the thickness direction, and the magnetic recording layer has a coercive force in the thickness direction that is greater than that in the in-plane direction. A second magnetic layer having a coercive force in the in-plane direction larger than that in the thickness direction is provided on the first magnetic layer.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

FIG. 4 shows a cross-sectional view of a perpendicular magnetization recording medium which is an embodiment of the present invention. In this embodiment, a high magnetic permeability layer 3 is provided on a substrate 2 made of a non-magnetic material, and a layer 3 of high magnetic permeability is further provided on the substrate 2 made of a non-magnetic material.
The first magnetic layer 1 is made of an alloy thin film of and chromium (Or).
1 and a second magnetic layer 12. In this case, the composition of the alloy thin film may be 15 to 20% by weight of Or, as long as the perpendicular anisotropy is not lost.

Specifically, first, Fe is deposited as a high magnetic permeability layer 3 on a substrate 2 made of a polymer film by sputtering.
A first magnetic layer made of a GoOr alloy is formed on the Fe-Ni alloy thin film 3, and the coercive force Hc,t in the thickness (perpendicular) direction is thicker than the coercive force He/in the in-plane direction. 11 is formed to a thickness of 0.4 μm by sputtering. Further, on the first magnetic layer 11, as a second magnetic layer 12, a GoOr alloy thin film having a coercive force HC/ in the in-plane direction larger than the coercive force Ha in the thickness direction is formed by 0.1 μm.
It is formed by m-sputtering method. Second magnetic layer 12
For the thickness of the first magnetic layer 11, 'Ao-Akira' is appropriate. At this time, the coercive force Hc in the thickness direction and the coercive force Hat in the in-plane direction can be arbitrarily changed by selecting the GoOr sputtering conditions.

For example, the coercive force Ha in the thickness direction is the coercive force in the in-plane direction)
A larger first magnetic layer 11 is obtained by increasing the substrate temperature, and the coercive force HC/ in the in-plane direction is higher than the coercive force Ha in the thickness direction.The larger second magnetic layer 12 is obtained by lowering the substrate temperature. It can be obtained by In addition, by setting the gas pressure during sputtering to 20 mTorr or less, a first magnetic layer 11 having a larger coercive force 1 in the thickness direction (c is larger than the coercive force HC in the in-plane direction) can be obtained, and the gas pressure range exceeding 20 mTorr can be obtained. For example, by performing sputtering at 80 mTorr, the second magnetic layer 12 can be obtained in which the coercive force HC/ in the in-plane direction is larger than the coercive force Hc in the thickness direction.

The reproduction characteristics of the perpendicular magnetization recording medium of this example are shown by the broken line in FIG. For comparison, the figure also shows the results when the thickness of the single magnetic layer shown in FIG. 3 was 0.2 μm and 0.5 μm. In this example, the thickness of the first magnetic layer 11 is 0.4 μm.
, coercive force in the thickness direction) f and coercive force H in the in-plane direction
C/ are respectively 500 Oe and 2000e.
The thickness of the second magnetic layer 12 is 0.1 μm, the coercive force in the thickness direction (on IC) is 3000e, and the coercive force H (+/ ) in the in-plane direction is 42008. By the way, the thickness of the conventional example is 0.2 μm. The coercive force HOI in the thickness direction of a single-layer perpendicular magnetization layer of 0.5 μm is 52006.4900 el, and the coercive force He/ in the in-plane direction is 21006 and 22 el, respectively.
It is 00e.

As is clear from the figure, the perpendicular magnetization recording medium having the structure according to this example has improved recording density-reproducing output characteristics. Although the reason for this is unknown, the following explanation can be considered. An electromagnetic induction type vertical head generates a reproduction output where the magnetic flux density from the medium changes, and the greater the degree of change, the greater the reproduction output can be obtained. That is, in the perpendicular magnetization recording method, the reproduction output is determined at the point where the magnetization is reversed. Incidentally, in a perpendicularly magnetized recording medium, the demagnetization effect becomes extremely small near the boundary region (transposition region) where magnetization is reversed according to a recorded signal, and the magnetic moment becomes almost equal to the saturation magnetization (Ms). Therefore, the magnetic flux density on the medium surface in the dislocation region is expressed as the product of Ms and the thickness of the perpendicular magnetization layer, so
Thick media have a large magnetic flux density, which blocks the magnetic flux on the opposite side of the boundary. Therefore, by providing a second magnetic layer 12 having a high coercive force HC/ in the horizontal direction on the surface of the perpendicular magnetic layer, it is possible to prevent the magnetic flux from binding, and the vertical head can effectively produce reproduction output. It becomes possible.

Although the present invention has a two-layer structure consisting of a first and second magnetic layer, the ratio of the coercive force in the thickness direction to the coercive force in the in-plane direction is 11.
c on /Hc / is 1 from the substrate side in the thickness direction of the magnetic layer.
A case where the number continuously changes from above to below 1 is also a type of two-layer structure and is included in the scope of the present invention.

Furthermore, the present invention is not limited to only cocr alloys,
For example, cobalt vanadium (4) can also be used. Furthermore, the scope of the present invention is limited to the magnetic recording layer, and it goes without saying that it does not matter whether the medium has a high magnetic permeability layer between the magnetic recording layer and the substrate or the medium does not have a high magnetic permeability layer. It is.

Effects of the Invention In short, the present invention has a first magnetic recording layer having at least a magnetic recording layer having an axis of easy magnetization in the thickness direction, and in which the magnetic recording layer has a coercive force in the thickness direction larger than that in the in-plane direction. The present invention provides a perpendicularly magnetized recording medium in which a second magnetic layer is provided on the magnetic layer, the coercive force in the in-plane direction being larger than the coercive force in the thickness direction, and it has excellent recording density-reproduction output characteristics. That's what you get.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of a normal perpendicular magnetization recording medium with a high magnetic permeability layer, Figure 2 is a structural diagram of a conventional perpendicular recording/reproducing magnetic head, and Figure 3 is a recording density-reproduction of a conventional perpendicular magnetization recording medium. FIG. 4 is a cross-sectional view of a perpendicular magnetization recording medium according to an embodiment of the present invention, and FIG. 6 is a diagram showing the recording density-reproduction output characteristic of the perpendicular magnetization recording medium of the present invention. 2... Substrate, 3... High magnetic permeability layer, 11...
...First magnetic layer, 12...Second magnetic layer.

Claims (1)

[Claims] The magnetic recording layer has at least a magnetic recording layer having an axis of easy magnetization in the thickness direction, and the magnetic recording layer has an in-plane magnetic recording layer on a first magnetic layer having a coercive force in the thickness direction larger than that in the in-plane direction. 1. A perpendicular magnetization recording medium comprising a second magnetic layer having a coercive force in a direction larger than a coercive force in a thickness direction.