JPS60217523A - Vertical magnetic recording medium - Google Patents

Abstract

PURPOSE:To obtain a magnetic recording medium having excellent recording and reproducing characteristics by forming the ''Permalloy'' films made into the multi-layered structure in which said films are separated by >=1 layers of Ti films on a nonmagnetic substrate and forming a vertically magnetized Co-Cr film on the ''Permalloy'' films directly or via the Ti film of which the surface is oxidized. CONSTITUTION:The ''Permalloy'' film 4, the Ti film 5, more particularly the Ti film of which the surface is oxidized by exposing the same to an oxygen atm. and further the film 4 are formed on the non-magnetic substrate and thereafter the vertically magnetized Co-Cr film 2 is formed thereon. Or plural layers of the surface-oxidized Ti film 5 and plural layers of the films 4 are alternately formed on the substrate 1 and thereafter the film 2 is formed. The magnetic recording medium which has the magnetized film 2 having good C-axis orientability and excellent recording and reproducing characteristics is obtd.

Description

[Detailed description of the invention] Industrial applications The present invention is a perpendicular magnetic recording device with excellent high-density recording characteristics. Regarding recording media.

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. A Co-Or perpendicular magnetic recording medium, called a single-layer film medium, is one in which a perpendicularly magnetized film mainly composed of Co-Cr is formed on a substrate made of a nonmagnetic material by sputtering or vacuum evaporation. . For a single-layer film medium with 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 medium. In particular, when recording and reproducing using the known auxiliary pole excitation type vertical head, the recording efficiency is improved by about 20 dB and the reproduction output is improved by about 20 dB.

One of the reasons why the recording and reproducing characteristics of the dual-layer film medium are significantly superior to those of the single-layer film media as described above is that the permalloy film 3 operates as a 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 possible to optimize the material composition 9 manufacturing conditions, etc., but in addition to these, it is also possible to increase μ by changing the film structure. That is, by forming the permalloy film 4 into a multilayer structure separated by a non-magnetic layer 6 as shown in FIG.
The inventors have confirmed that μ increases. The reason for this is thought to be that in a permalloy film with a multilayer structure, the domain wall energy decreases due to magnetostatic interaction between each layer. Note that the permalloys shown in FIGS. 2 and 3 are referred to as a two-layer structure and a three-layer structure, respectively. Hereinafter, since the effects of the present invention are the same for a two-layer structure and a structure of three or more layers, a two-layer structure of permalloy will be explained.

The non-magnetic layer 5 for making the permalloy film into a multilayer structure is Teha, AI, Al2O3, Cu, Tt, St, 5i.
Although a noise deviation such as n2 may be used, the crystal orientation of the Co--Cr film 3 must be taken into consideration at this time. That is,
In order for the Co-Or 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 by inserting the nonmagnetic layer 5, this orientation can be disturbed. If this occurs, it is undesirable because it leads to deterioration of recording and reproducing characteristics.

Purpose of the Invention The present invention has been made in view of the above points.
2 consisting of a Cr perpendicular magnetization film and a multilayer permalloy film
An object of the present invention is to provide a layered film medium having a structure in which a Co--Cr perpendicular magnetization film with good C-axis orientation can be obtained.

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

DESCRIPTION OF EXAMPLES A two-layer film medium having the structure shown in FIG. 2 was prepared by a vacuum evaporation method, and the C-axis orientation of the Co-0r film 2 was investigated. An example of the results is shown in the table below. As a non-magnetic layer, A1゜A I2O3l
Cu + S i , S i02 , and T l were investigated. Note that Al, Cu.

Regarding Ti, in addition to forming permalloy films directly on these nonmagnetic layers, we also conducted experiments in which permalloy films were formed after oxidizing these surfaces.

The thickness of the permalloy film 4 is 1700A, and the thickness of the two layers is 34o.
O people. Also, non-magnetic layer 5. The thickness of the Co-Cr film 2 was 200A and 2000A, respectively.

The C-axis orientation of the Go-Cr film is evaluated by the half value Δθ5° of the rocking curve for the (002) plane, and the smaller this value is, the better the orientation is. From the table, Al2O3,
Δθ for Cu, Cu (surface oxidation), Si, and S102.

is 20 degrees or more, and the orientation is quite poor. On the other hand, Ti is 14 degrees, and Ti (surface oxidation) is 8 degrees, indicating that Ti (surface oxidation) is the most excellent as a nonmagnetic layer. As described above, the reason why Ti (surface oxidation) is the most excellent as a nonmagnetic layer for separating permalloy films is considered to be as follows. The Ti film has a dense hexagonal structure, and when vacuum evaporation is performed, the C-axis is easily oriented in the direction perpendicular to the film surface. When a permalloy film is formed on top of this,
It grows epitaxially, and the (111) plane of the face-centered cubic structure is oriented parallel to the film surface. When a Cc)-Cr film is formed on this oriented permalloy film, this also grows epitaxially, and the C axis is oriented in the direction perpendicular to the film surface. It is thought that the effect of such epitaxy is accentuated by oxidizing the Ti surface. Note that Δθ for nonmagnetic layers other than Ti and Ti (surface oxidized). The reason why is not small is probably that the crystal system, lattice constant, orientation, etc. are not conditions that would allow the ;Co-0r film to be vertically aligned.

Furthermore, Ti and Ti (surface oxidation) can be clearly distinguished by Auger electron spectroscopy. Figure 4 shows T as a non-magnetic layer.
2 of the structure shown in Figure 2 using i (surface oxidation).
This is an Auger depth profile in the thickness direction of a layered film medium. Elements include Co and Ni.

Ti and O are indicated. In the figure, the part indicated by arrow A is the medium surface, B is the boundary between the Co--Cr film and the permalloy film, C and D are the boundaries between the permalloy film and the Ti film, and E is the boundary between the permalloy film and the nonmagnetic substrate. Note that in the Ti film, the boundary C side and the boundary D side are respectively referred to as the front surface and the back surface. Fourth
In the figure, oxygen of Ti, which is surface oxidized, can be seen at boundary C. On the other hand, in the case of Ti whose surface is not oxidized, almost no oxygen is seen at the boundary C.

Above, an example was described in which a Co-Cr perpendicular magnetization film was formed directly on a permalloy film, but the permalloy film and Co
The present invention is also effective when a T1 film is present between the -Cr perpendicular magnetization film.

Next, a more specific example will be described.

As an example of the present invention, a two-layer film medium having a two-layer permalloy film as shown in FIG. 2 was fabricated by vacuum evaporation. As a non-magnetic substrate, a polyimide film with a film thickness of 60 μm was used, and on this a permalloy film with a film thickness of 1B00 was first deposited, and then on top of that, a film with a film thickness of 50 μm was deposited.
A Ti film of , was deposited.

After this, the surface of the Ti film was exposed to an oxygen atmosphere to form an oxide layer. Next, a permalloy film with a thickness of 1800 Å was deposited thereon, and a Co-0r perpendicular magnetization film with a thickness of 200 Å was deposited thereon.

The resulting Co--Cr perpendicular magnetization film had a Δ05° of 8.4 degrees, and had sufficient characteristics as a two-layer film medium.

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. 2 and 3 are cross-sectional views showing an example of the structure of a two-layer film medium having a multilayer permalloy film, and FIG. 1 is an Auger depth profile of a two-layer film medium according to the invention. 1...Substrate made of non-magnetic material, 2...
・Co-0r perpendicular magnetization film, 3... Permalloy film with single layer structure, 4... Permalloy film with multilayer structure,
6...Nonmagnetic layer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 4
figure

Claims (1)

[Claims] In a two-layer film medium in which a permalloy film is formed on a nonmagnetic substrate and a Co-Cr perpendicular magnetization film is formed on the permalloy film directly or via a Ti film, the permalloy film is separated by at least one layer of Ti film. 1. A perpendicular magnetic recording medium characterized in that the Ti film has a multilayered structure, and the surface of the Ti film is oxidized.