JPS60217522A - Vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent high reproduction output by having he multi-layered structure of ''Permalloy'' films separated by >=1 layers of Ti films on a non-magnetic substrate, forming >=1 layers of the Ti films in the form of discontinuous films and forming a vertically magnetized Co-Cr film on the ''Permalloy'' films. CONSTITUTION:The ''Permalloy film'' 4 and the thin Ti film 6 are formed on the substrate 1 consisting of a heat resistant high polymer film, etc. by stopping once deposition then starting deposition again without depositing continuously the Ti over the entire layer to the entire film thickness. The ''Permalloy'' film 4 is again formed thereon and the vertically magnetized Co-Cr film is formed thereon. The ''Permalloy films'' are otherwise separated by the plural Ti films and the multi-layered structure is made by forming the ''Permally'' film 4 on the substrate 7, the Ti film 8 deposited continuously in the thickness direction, the film 4, the Ti film deposited again after stopping once the deposition in the thickness direction, the film 4 and the film 2. The magnetic recording medium which has excellent recording and recording characteristics and is suitable for high-density recording is thus obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a medium for perpendicular magnetic recording that has excellent high-density recording characteristics.

Conventional Structure and Problems There is a perpendicular magnetic recording system as a magnetic recording system with excellent short wavelength recording characteristics. This method requires a perpendicular magnetic recording medium whose axis of easy magnetization is approximately perpendicular to the film surface of the medium. When a signal is recorded on such a medium, the residual magnetization is oriented in a direction substantially perpendicular to the film surface of the medium, and therefore, the shorter the wavelength of the signal, the smaller the demagnetizing field within the medium, resulting in excellent reproduction output. Co-Cr perpendicular magnetic recording media, also known as single-layer media, are made by depositing a perpendicularly magnetized film containing CO and Cr as main components on a substrate made of non-magnetic material using sputtering or vacuum evaporation methods (such as ion blating). (including a method in which some of the evaporated atoms are ionized and deposited). For a single-layer film medium having such a structure, a substrate 1 made of a non-magnetic material and a Co-Cr perpendicularly magnetized film 2 as shown in FIG.
It is known that recording efficiency and reproduction output can be improved by creating a structure called a so-called two-layer film medium in which a No(-Malloy film 3 is provided between the When recording and reproducing using a vertical head, the recording efficiency is improved by approximately 20 dB, and the reproduction output is approximately 20 dB.
Improve within dB.

As mentioned above, one of the reasons why the recording and reproducing characteristics of the dual-layer film media are significantly superior to that of the single-layer film media is as follows: )(-Malloy film 3
This is because it operates as part of the head. Therefore, it is desirable that the magnetic permeability μ of the permalloy film 3 is large. In order to increase μ, it is conceivable to optimize the manufacturing conditions of the material composition 9, but in addition to these, it is also possible to increase μ by changing the film structure. That is, as shown in FIG. 2 or 3, by separating the permalloy film 4 into two or more layers with the nonmagnetic layer 6, the first
The present inventors have confirmed that μ is larger than the permalloy film 3 having a single layer structure shown in the figure. Here, the permalloys shown in FIGS. 2 and 3 are referred to as a two-layer structure and a three-layer structure, respectively, and a structure with two or more layers is referred to as a multilayer structure.

Moreover, the reason why μ increases when the permalloy film has a multilayer structure is thought to be that in the multilayer permalloy film, the domain wall energy decreases due to magnetostatic interaction between each layer.

The nonmagnetic layer 6 used to make the permalloy film into a multilayer structure includes AI, Al2O3, Cu, Tt, Si, and 5i.
Any film such as n2 may be used, but the crystal orientation of the Co--Cr film 3 must be taken into consideration at this time. That is, C
.

- In order for the Cr film to be a perpendicularly magnetized film, the C-axis of the dense hexagonal structure must be oriented in a direction substantially perpendicular to the film surface, but the inclusion of the non-magnetic layer 5 disrupts the orientation. This is undesirable because it leads to deterioration of recording and reproducing characteristics. As a result of experiments conducted by the present inventors, it was found that Ti was used as the nonmagnetic layer 5.
Although the C-axis orientation of the C0-Cr film was the best when using C0-Cr, the properties were still not sufficient, and further improvement of the properties was desired.

OBJECTS OF THE INVENTION An object of the present invention is to provide a two-layer film medium that has even better recording and reproducing characteristics than conventional two-layer film media.

Structure of the Invention The present invention provides a two-layer film medium in which a permalloy film is formed on a non-magnetic substrate, and a C0-Cr perpendicularly magnetized film is formed on the permalloy film directly or via a non-magnetic layer. The present invention relates to a perpendicular magnetic recording medium characterized in that it has a multilayer structure separated by one Ti film, and at least one of the Ti films is a discontinuously formed film.

DESCRIPTION OF EMBODIMENTS The present invention will be explained using FIG. 4. FIG. 4 shows the basic structure of an example of the two-layer film medium of the present invention, which differs from the conventional two-layer film medium shown in FIG. 2 in the structure of the Ti film. That is, while the Ti film in the conventional two-layer medium is a continuously formed film, in the present invention it is a discontinuously formed film. Note that the term "continuously formed film" as used herein refers to a film that is continuously deposited over the entire thickness of Ti. FIG. 4 shows a case where a discontinuously formed Ti film 6 with a two-layer structure is provided.
This structure is a film formed by not continuously depositing a film over the entire film thickness of T1, but by stopping the deposition midway through the deposition and starting the deposition again. The same applies to discontinuously formed films having a structure of three or more layers. In this way, once deposition is stopped midway through deposition, the surface condition changes while deposition is stopped.

Even if the surface temperature decreases and the deposition is restarted to form the full film thickness, a boundary layer is generated in the area where the deposition has stopped.

This layer is observed by SEM (scanning electron microscope), Auger depth profile, or the like.

A two-layer film medium having the structure shown in Fig. 4 was prepared using a discontinuous Ti film, and the orientation and recording/reproducing characteristics of the Go-Cr film were measured. It was confirmed that the playback output was improved compared to the two-layer film medium, and the reproduction output was increased. This will be explained below.

The table below summarizes an example of the orientation and μ of the Co-Or film of the conventional and inventive two-layer film media. The orientation is (0
02) Half width Δθ of the rocking curve regarding the surface. The smaller this value is, the better the orientation is.

From the table above, it can be seen that the medium with the structure shown in FIG. 1, which is an example of a conventional two-layer film medium, has a difference of Δθ5° and Although both μ is improved, the medium of the present invention having the structure shown in FIG. 4 shows a further improvement in Δθ5°. The reason why the excellent Δθ5° is obtained as described above is considered to be as follows. T
The i-film has a dense hexagonal structure, and when the film is deposited by vacuum evaporation or sputtering, the C-axis is easily oriented in the direction perpendicular to the film surface. When a permalloy film is formed on this, it grows epitaxially, and the (111) plane of the face-centered cubic structure is oriented parallel to the film surface. When a Co-0r film is formed on this oriented permalloy film, it also grows epitaxially and the C-axis is oriented in the direction perpendicular to the film surface. Therefore, Ti
It is necessary to improve the C-axis orientation of
This is thought to be because the C-axis orientation of the discontinuously formed Ti film is better than that of the continuously planarized Ti film.
2) and the reproduction output of the medium of the present invention (FIG. 4). The total thickness of the permalloy film was 3000 Å, the thickness of the Co-Cr perpendicular magnetization film was 1000 Å, and the total thickness of the Ti film in FIGS. 2 and 4 was 400 Å. In addition, signal recording and reproduction is performed using an auxiliary magnetic pole excitation type vertical head, and the recording density is 1ooKFRP.
It was set as I. Note that 100KFRPI is a recording state of a digital signal in which magnetization is reversed 10oOoO times per inch.

If the reproduction output of the medium having the structure shown in FIG. 1 is odB, then the medium having the structures shown in FIGS. 2 and 4 had outputs of 10 ydB and +12 dB, respectively. Therefore, it can be seen that by forming the Ti film discontinuously, the reproduction output is significantly higher than that of the conventional two-layer film medium.

Although the case of a permalloy film with a two-layer structure has been described above, the same can be said in the case of a permalloy film with a three-layer structure or more as shown in FIG. In other words, if at least one layer of the Ti film that separates the permalloy film into multiple layers is a discontinuously formed film, Δθ will be lower than that of the conventional two-layer film medium. The smaller the value, the greater the playback output. Furthermore, in the above, an example was described in which a Co-Cr perpendicularly magnetized film was formed directly on a permalloy film, but between the permalloy film and the Co-0r perpendicularly magnetized film, there is The present invention is also effective when a nonmagnetic layer having a centered cubic structure is present.

Next, a more specific embodiment will be explained.0 First Embodiment A first embodiment of the present invention will be described with reference to FIG. In the same figure, 7 is a heat-resistant polymer film with a thickness of 12 μm, 2 is a Co-Cr perpendicular magnetization film with a thickness of 120 OA, and 4 is a heat-resistant polymer film with a thickness of 12 μm.
8 is a continuously formed Ti film having a film thickness of 800 mm, and 6 is a discontinuously formed Ti film having a two-layer structure having a film thickness of 300 mm. When a 100 KFRPI signal was recorded and reproduced on a two-layer film medium having such a structure using an auxiliary magnetic pole excitation type vertical head, a reproduction output 3 odB higher than that of a conventional CO-containing iron oxide coating type medium was obtained. In addition, instead of the discontinuously formed T1 film 6, a continuously formed Ti film with a film thickness of 300 mm was used.
Even with a two-layer film medium having the same structure as shown in FIG. 6 except that a film was used, an output higher by s dB was obtained.

Second Embodiment A second practical example of the present invention will be described with reference to FIG. In the figure, 7 is a heat-resistant polymer film with a film thickness of 12 μm, 2 is a Co-Cr perpendicular magnetization film with a film thickness of 1200 μm, 4 is a malloy film with a film thickness of 1000 μm, and 9 is a film with a film thickness of 100 μm. The continuous Ti film 6 is a discontinuous Ti film having a two-layer structure with a thickness of 300 mm. This Ti film 9 is Co-C
r This is provided to improve the orientation of the perpendicularly magnetized film. When a 100 KFRPI signal was recorded and reproduced using an auxiliary magnetic pole excitation type perpendicular to a two-layer film medium having such a structure, a reproduction output 32 dB higher than that of a conventional CO-containing iron oxide coating type medium was obtained.

Effects of the Invention According to the present invention, a perpendicular magnetic recording medium with excellent recording and reproducing characteristics can be provided.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view showing the structure of a conventional two-layer film medium, FIGS. The figures are cross-sectional views showing one example of the structure of a two-layer film medium according to the present invention, and FIGS.
The figures are cross-sectional views showing the configurations of two-layer film media that are first and second embodiments of the present invention, respectively. 1...Substrate made of non-magnetic material, 2...
・Co-Cr perpendicular magnetization film, 3... Permalloy film with single layer structure, 4... Permalloy film with multilayer structure,
5...Nonmagnetic layer, 6...Discontinuous formation T
i film, 8, 9... Continuously formed Ti film. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
figure

Claims (1)

[Claims] In a two-layer film medium in which a permalloy film is formed on a non-magnetic substrate, and a Co-Cr perpendicular magnetization film is formed on the permalloy film directly or via a non-magnetic layer, the permalloy film is formed of at least one layer of Ti film. It has a separated multilayer structure,
A perpendicular magnetic recording medium characterized in that at least one layer of the Ti film is a discontinuously formed film.