JPH0357536B2 - - Google Patents

Description

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

Conventional configuration and its problems As a magnetic recording system with excellent short wavelength recording characteristics,
There is a perpendicular magnetic recording method. 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. Therefore, the shorter the wavelength of the signal, the smaller the demagnetizing field within the medium, and excellent reproduction output can be obtained. Perpendicular magnetic recording media generally have a magnetic layer on a substrate, which is mainly composed of Co and Cr and has an axis of easy magnetization approximately perpendicular to the film surface (hereinafter this magnetic layer is referred to as a Co-Cr perpendicular magnetization film). It was formed by a sputtering method. However, the sputtering method has a slow film formation rate and is not suitable for mass production. In contrast to the sputtering method,
According to a vacuum evaporation method (including a method in which a portion of evaporated atoms are ionized and deposited, such as an ion plating method), the film formation rate is increased by more than two orders of magnitude, and mass productivity is improved. The present inventors have found that a Co-Cr perpendicular magnetization film can also be obtained by vacuum evaporation, and found that the Co-Cr film obtained by vacuum evaporation is a perpendicular magnetization film with excellent electromagnetic conversion characteristics. The conditions for this have not been found.

OBJECTS OF THE INVENTION The object of the present invention is to provide conditions for a Co--Cr film obtained by vacuum evaporation to become a perpendicularly magnetized film with excellent electromagnetic conversion characteristics.

Structure of the Invention The present invention provides that in a Co-Cr perpendicularly magnetized film having a columnar structure formed by vacuum evaporation, Cr is segregated near the grain interface of columnar crystal grains, and the Cr concentration in the region near the grain interface is , the average Cr of this film
It is characterized by having a concentration of 1.7 times or more.

DESCRIPTION OF EMBODIMENTS The present invention will be described with reference to FIGS. 1 to 5. FIG. 1 is a schematic diagram of a fractured surface of a Co--Cr vapor deposited film.
1 is a substrate. As the substrate, an aluminum plate, a film made of a polymer material, or a permalloy film formed on a non-magnetic material thereof is used. 2 is a Co--Cr perpendicular magnetization film, and 3 is a columnar crystal grain. A Co--Cr perpendicularly magnetized film generally has a columnar crystal structure, and the grain size of the columnar crystal grains is about 1/10 of the film thickness. For example, Co
The -Cr perpendicular magnetization film is composed of columnar crystal grains with a grain size of approximately 1000 Å. has a structure like this
Experiments have revealed that the magnetic properties of a Co-Cr perpendicularly magnetized film largely depend on the amount of Cr present near the grain interface of columnar grains.

FIG. 2 shows a schematic diagram of a fractured surface of a Co--Cr perpendicularly magnetized film in which Cr is segregated near the grain interface of columnar crystal grains. 4 is a Co-Cr perpendicular magnetization film in which Cr is segregated, 5
6 is a columnar crystal grain in which Cr is segregated, and 6 is a portion in which Cr is segregated near the grain interface of the columnar crystal grain. Note that the grain interface of columnar crystal grains refers to the portion indicated by the solid line 7 in FIG. 3, and does not include the portion indicated by the broken line 8. The composition near the grain interface of columnar grains is
For example, it can be investigated by methods such as Auger electron spectroscopy.

In a Co-Cr perpendicularly magnetized film, the ratio of the Cr concentration (Cr/(Co+Cr)) in a region approximately 10 Å thick near the grain interface of columnar grains to the average Cr concentration of the entire film, Mr⊥/Mr Figure 4 shows the relationship between
However, Mr⊥ is not demagnetically corrected,
This is the residual magnetization in the direction perpendicular to the film surface, and Mr is the residual magnetization within the film surface. From FIG. 4, as the ratio of the Cr concentration in the approximately 10 Å thick region near the grain interface of the columnar crystal grains to the average Cr concentration of the entire film increases, Mr⊥/Mr also increases, and the ratio becomes 1.7.
If it becomes more than 1, then Co with Mr⊥/Mr of 1 or more
It can be seen that a -Cr perpendicular magnetization film can be obtained.

Mr⊥/Mr is closely related to the characteristics when a signal is recorded and reproduced in a Co--Cr perpendicularly magnetized film (this characteristic is called electromagnetic conversion characteristic). Figure 5 shows a well-known auxiliary pole excitation type head with a Co-Cr perpendicular magnetization film of 100 KFRPI (the number of magnetization reversals per inch).
The state of digital records, like 100,000 times.
This shows the relationship between the playback output and Mr⊥/Mr when a signal of 100KFRPI is recorded and played back. From this figure, it can be seen that when Mr⊥/Mr becomes less than 1, the reproduction output decreases significantly. The reason for this is that if Mr⊥/Mr is greater than or equal to 1, when a signal is recorded, the residual magnetization in the medium is mainly oriented perpendicular to the film surface, resulting in perpendicular recording.
This is thought to be because when Mr⊥/Mr becomes less than 1, the residual magnetization also becomes oriented in the in-plane direction of the film, resulting in a state similar to in-plane recording. To summarize the results shown in Figures 4 and 5 above, Cr in the approximately 10 Å thick region near the grain interface of columnar grains
When the ratio of the concentration to the average Cr concentration of the entire Co-Cr perpendicularly magnetized film becomes 1.7 or more, Mr⊥/Mr of the film becomes 1.
This means that excellent electromagnetic conversion characteristics can be obtained.

A specific example will be explained below.

First Example The first example will be described using FIG. 9 is a film made of a heat-resistant polymer material with a film thickness of 50 μm, on which a permalloy film 10 with a film thickness of 1 μm and a Co-Cr perpendicular magnetization film 11 with a film thickness of 1 μm are further formed on the film by vacuum evaporation. formed. According to Auger electron spectroscopy, the ratio of the Cr concentration in a region approximately 10 Å thick near the grain interface of the columnar crystal grains of this Co-Cr perpendicularly magnetized film to the average Cr concentration of the entire film is 2.1. Mr⊥／Mr
was 2.3. When a 100 KFRPI signal is recorded and reproduced on this medium using an auxiliary magnetic pole excitation type vertical head, it becomes
A 24dB higher output was obtained.

Second Example A second example will be described using FIG. Co-Cr perpendicular magnetization film 11 and permalloy film 10
A medium having almost the same structure as the first example was fabricated, except that a Ti vapor deposited film 12 with a thickness of 400 Å was present between the two. The Ti vapor deposited film is provided to improve the orientation of the Co--Cr perpendicular magnetization film. in this medium
The Cr concentration in the approximately 10 Å thick region near the grain interface of the columnar grains of the Co-Cr film is calculated based on the average of the entire film.
The ratio to the Cr concentration and Mr⊥/Mr are each 2.0.
and 2.4. When a 100 KFRPI signal is recorded and reproduced on this medium using an auxiliary magnetic pole excitation type vertical head, it becomes
28dB higher output was obtained.

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

[Brief explanation of drawings]

Figure 1 is a broken view of a Co-Cr vapor deposited film, and Figure 2 is a Co-Cr-deposited film with Cr segregated near the grain interface of columnar grains.
A schematic diagram of the fracture surface of a perpendicularly magnetized Cr film. Figure 3 is a diagram for explaining the grain interface. Figure 4 shows the average Cr concentration and magnetic layer in a region approximately 10 Å thick near the grain interface of columnar crystal grains. and the ratio of Cr concentration to Mr⊥／Mr
FIG. 5 is a diagram showing the relationship between Mr FIG. 3 is a cross-sectional view of the medium. 4... Co-Cr perpendicular magnetization film with Cr segregation, 5...
... Columnar crystal grains with Cr segregated, 6... Parts where Cr is segregated near the grain interface of the columnar crystal grains,
7... Grain interface of crystal grains.

Claims (1)

[Claims] 1. A thin magnetic layer containing Co and Cr as main components is formed on a substrate and has an axis of easy magnetization in a direction substantially perpendicular to the film surface,
Cr is segregated near the grain interface of the columnar crystal grains constituting the magnetic layer, and the Cr concentration in the region near the grain interface is 1.7 of the average Cr concentration of the magnetic layer.
A perpendicular magnetic recording medium characterized in that it is more than twice as large.