JPS5975429A - Vertically magnetized magnetic recording medium - Google Patents

Abstract

PURPOSE:To improve the orientation property of a ''Permalloy'' film and a Co-Cr film and to improve a recording and reproducing characteristic by forming a Ti film in a multilayered construction on a substrate and forming the Co-Cr vertically magnetized film, via the ''Permalloy'' film, on the Ti layer. CONSTITUTION:A Ti layer of 300Angstrom per layer is formed in >=2 layers, by superposing the same in three layers, in this embodiment, on a substrate 1 of Al or a high polymer material. A ''Permalloy'' film 3 is formed to 1,500Angstrom thickness on said layer and thereafter a vertically magnetized film 2 consisting essentially of Co and Cr is formed. When the vapor deposition is once stopped after the vapor deposition of one layer in the stage of forming the Ti layer by vapor deposition, the surface produces a boundary layer with the succeeding layer owing to oxidation, a decrease in temp., etc., thus giving a favorable influence. The parallel orientation property of the film 3 with respect to the film plane is improved by the laminated Ti film 10 and the vertical orientation property of the vertically magnetized film to be formed on the film 3 is improved as well. The recording and reproducing characteristic better than conventional recording media is thus obtd. The higher reproducing output is obtd. by providing a single Ti layer 4 further on the layer 3.

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, called single-layer media, are made by depositing a perpendicularly magnetized film mainly composed of Co and Cr on a substrate made of non-magnetic material using sputtering or vacuum evaporation methods (such as ion-blating methods). (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 so-called two-layer film in which a permalloy film 3 is provided between a substrate 1 made of a non-magnetic material and a Co--Cr perpendicular magnetization film 2, as shown in FIG. It is known that recording efficiency and reproduction output can be improved by using a structure called a film medium. In particular, when performing internal recording using a well-known plane-assisted, separately-excited vertical head, the recording efficiency is improved by approximately 2 odB, and the reproduction output is approximately 20 dB.
B improve.

In order for a two-layer film medium as shown in FIG. 1 to have excellent recording and reproducing characteristics, it is necessary to
It is necessary that the C axis of the ap structure is oriented perpendicular to the film surface. For this purpose, the fcc structure of the permalloy film 3 (1
11) Although it is required that the plane be oriented parallel to the film surface, it is possible to form such a film on a substrate made of a non-magnetic material such as At or a polymer material. It is difficult. In order to solve these difficulties, a two-layer film medium having a structure as shown in FIG. 2 has been considered. In the medium shown in FIG. 2, a permalloy film 3 is formed on a substrate made of a non-magnetic material via a single-layer f'i film 4. By adopting such a structure, The (111) plane of the permalloy film is easily oriented parallel to the film surface, and as a result, the C-axis orientation of the co-Cr perpendicularly magnetized film 2 is improved, and the recording and reproducing characteristics are improved. A two-layer film medium, especially a two-layer film medium as shown in Figure 2, provides excellent recording and reproducing characteristics, but it is important to consider miniaturization of magnetic recording and reproducing devices such as audio tape recorders and video tape recorders. However, the characteristics are still not sufficient, and further improvement in recording and reproducing characteristics is desired.Object of the InventionThe present invention provides a two-layer film medium with even better recording and reproducing characteristics than conventional two-layer film media. The purpose is to provide

Structure of the Invention The present invention provides a two-layer film medium in which a Ti film is formed on a substrate and a Co-Cr perpendicular magnetization film is formed thereon via a permalloy film, characterized in that the Ti11g has a multilayer structure. It is something to do.

With the above structure, the orientation of the permalloy film and the Co--Cr perpendicular magnetization film is improved compared to the conventional two-layer film medium, and as a result, the recording and reproducing characteristics are improved.

DESCRIPTION OF EMBODIMENTS The present invention will be explained using FIGS. 3 and 4. FIG. 3 shows the basic structure of the two-layer film medium of the present invention, and the conventional two-layer film medium shown in FIG. In contrast, the structure of the r1 membrane is different. That is, whereas the 1''i film in the conventional two-layer medium has a single layer structure, the present invention has a multilayer structure. Note that the single-layer structure referred to here refers to a structure in which Tl is continuously deposited over the entire film thickness. Figure 3 is 2
This shows the case where a layered Ti film is provided.In this structure, the film is not deposited continuously over the entire thickness of the Ti film, but the deposition is stopped once in the middle of the deposition and then started again. This refers to the produced membrane.

The same applies to films with a structure of three or more layers. Note that a structure with two or more layers is referred to as a multilayer structure. In this way, if the precipitation is stopped midway through the deposition, surface oxidation 2 and a decrease in the surface temperature will occur while the precipitation is stopped, and even if the precipitation is started again and the full film thickness is formed, the precipitation will not be completed. A boundary layer is formed in the stopped area. This layer is observed using a SEM (scanning electron microscope) or the like.

A two-layer film medium having the structure shown in Fig. 3 was prepared by making the Ti film into a multilayer structure, and the permalloy film and Go-C
When the orientation and recording/reproduction characteristics of the r-film were measured, it was confirmed that the orientation of both films was better than that of the conventional two-layer film medium, and that the reproduction output was increased by J. This will be explained below.

The table below summarizes the orientation of the permalloy film and the co-Cr film of the conventional and inventive two-layer film media.

The orientation of the permalloy film is (111), and the half-width of the rocking curve is Δθ5° (111), (,,'
The orientation of the o-Cr film is expressed by the half-width Δθ5° (002) of the rocking curve with respect to the (002,) plane, and the smaller these values, the better the orientation.

From the table above, in the conventional two-layer film media, △θso
(1i 1) is 23° and 12°, whereas
In the present invention, the angle is 8°, and Δθeso
It can be seen that (002) is 6° in the present invention, compared to 2o0 and 10° in the conventional case. As described above, in the two-layer film medium of the present invention, Δθso
Both (111) and Δ(/6o(002)) are small, and the orientation is improved.

FIG. 4 shows the reproduction output when the total film thickness and structure of the fl film are changed in a two-layer film medium. Note that the film thicknesses of the permalloy film and the co-Cr perpendicular magnetization film are both 150
The number of people remains constant at 0. The signal is recorded and reproduced using an auxiliary magnetic pole excitation type vertical head, and the recording density is 50KFRPI.
and 17. Furthermore, 60KFRPI means 5 per inch.
This is a recording state of a digital signal with 0,000 magnetization reversals. Curve 6 in FIG. 4 corresponds to the case where the solid Ti film shown in FIG. 2 has a single layer structure. Curves 7 and 8 are the media of the present invention, where the T1 film has two-layer and three-layer structures, respectively. From FIG. 4, it can be seen that when the total thickness of the Ti film is constant, by forming the f1 film into a multilayer structure, the reproduction output is higher than that of the conventional two-layer film medium.

Next, a more specific example will be explained.

First Embodiment A first embodiment of the present invention will be described with reference to FIG. In the figure, numeral 9 is a film made of a heat-reducing polymer phase material with a thickness of 12 μm, 2 and 3 are a Co--Cr perpendicular magnetization film with a thickness of 1500 mm, and a permalloy film with a thickness of 1500 mm, respectively. 1o is an 'l' i film having a three-layer structure in which three 1'i films of 300A per layer are stacked. 100KFR with auxiliary pole excitation type perpendicular head on a two-layer film medium with this structure.
When a PI signal was recorded and reproduced, a reproduction output 22d.B higher than that of a conventional Co-containing iron oxide coated medium was obtained.

Ushi, except that the Ti film has a single layer structure and a film thickness of 900.
Even with a two-layer film medium having the same structure as shown in FIG. 5, a 5 dB higher output was obtained.

Second Embodiment A second embodiment of the present invention will be described with reference to FIG. There is a film thickness of 4 between the permalloy film and the Co-Cr perpendicular magnetization film.
The structure is the same as that shown in FIG. 5, except for the presence of the ri film to 0. This f'i film is provided to improve the orientation of the Co--Cr perpendicular magnetization film. 2 of such structure
100KF'R with auxiliary magnetic pole excitation type vertical head on layered film media
When a PI signal was recorded and reproduced, a reproduction output 24 dB higher than that of a conventional Co-containing iron oxide coated 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]

Figures 1 and 2 are diagrams showing the structure of a conventional two-layer film medium;
FIG. 3 is a diagram showing the basic structure of the magnetic recording medium of the present invention, and FIG. 4 is a diagram for explaining the present invention in detail, and is a diagram showing the relationship between the total thickness of the Ti film and the reproduction output. . 6 and 6 respectively show the first embodiment of the present invention. FIG. 3 is a diagram showing a magnetic recording medium according to a second example. 2...Co-0r perpendicular magnetization film, 3...Noku-Malloy film, 4...Ti film with single layer structure, 6...Ti film with two layer structure, 10... ...3-layer structure Ti film 0 Name of agent Patent attorney Toshio Nakao and 1 other person No. 11 Figure 5

Claims (1)

[Claims] A Ti film is formed on a substrate made of non-magnetic material, and its
A permalloy film is formed on the ri film, and CO and Or
1. A perpendicular magnetic recording medium, characterized in that a perpendicular magnetization film containing Ti as a main component is formed, and the Ti film has a multilayer structure.