JPH0358522B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a multipolar magnetization method for a magnetic film.

[Prior art and its problems]

In recent years, semi-hard or hard magnetic films have been used as recording materials in audio disks, and their use in OA equipment such as small pulse motors and encoders that utilize energy products is also rapidly expanding. In such applications, the number of divided magnetic poles has increased in order to increase recording density and detection accuracy, and the magnetic pole direction has also changed from in-plane direction to perpendicular direction of the film.

As a multi-pole magnetization method perpendicular to the film surface, a method is adopted in which a magnetic field corresponding to the width of the magnetic poles is applied while alternating the direction. This method had the disadvantage that it was necessary to use a different jig to match the width of the magnetic poles for each product, and that as the number of magnetic poles increased, the width of each magnetic pole became smaller, making it impossible to manufacture them with high precision.

[Purpose of the invention]

The present invention has been made to eliminate these drawbacks, and aims to provide a method for easily and accurately performing multi-pole magnetization without changing the jig. .

[Structure of the invention]

The multipolar magnetization method of the present invention involves preheating a semi-hard or hard magnetic film of Sm-Co, ferrite, etc. formed on a substrate to a temperature of 0.1 to 0.95 Tc of the Kyuri point Tc (°C), and then It is characterized by being magnetized in the thickness direction, then heating and demagnetizing part or more of the magnetized part with a laser or electron beam, and magnetizing this part using the magnetic field of the part that has not been heated and demagnetized. That is.

[Examples] Hereinafter, the present invention will be specifically described based on Examples.

First, a 1 μm thick SmCo ₅ film was formed on a Cu substrate by sputtering. in the thickness direction of this film
After applying an external magnetic field of 25 KOe to magnetize it in one direction, it was placed in a vacuum chamber. This apparatus is shown in FIG.
As shown in the figure, a film heating device 1, a sample magnetic film 2,
A laser beam introduction window 3 is placed inside a vacuum chamber 4, and a YAG laser oscillation device 5 is placed outside the vacuum chamber 4. This laser oscillation device 5 incorporates a beam diameter adjusting device and a beam direction changing device. First, the inside of the vacuum chamber 4 was evacuated to 5×10 ^-6 Torr or less, and the temperature of the membrane was maintained at 200°C. in this state
A beam energy of 10 ⁴ W/cm ² was applied to the part (a) in Figure 2, heated to 800°C, and then cooled. Then, the heating part was influenced by the magnetic field of the unheated part, and the magnetization direction was reversed, as shown in Figure 3.
Similar operations were performed on other parts of the film to finally achieve multipolar magnetization. When the width of one magnetic pole was measured, it was found to be within 15 μm ± 10%, which was achieved with high precision.

Next, by changing the preheating temperature, SmCo ₅ ,
Sm ₂ Co ₁₇ , Sm ₂ (Cu, FeCo) ₁₂ , CeCo ₅ , Gd−Co
Similar tests were conducted on materials mainly composed of rare earth elements and iron group elements such as It was found that this can be done with high accuracy. If it is less than 0.1 times, the magnetic film will crack due to the effects of rapid heating, and if it is more than 0.95 times, the demagnetized area will be wider than the area where the beam is irradiated, so it was found that the accuracy of the magnetic pole width deteriorates rapidly.

As can be seen from the above examples, after magnetization in the film thickness direction, a laser is used to heat a part of the preheated film to further demagnetize it, and after cooling, the magnetic field of other parts is used to further demagnetize the film. It is clear that if multi-pole magnetization is performed using a method of magnetizing parts, accurate magnetization can be performed with any magnetic pole width.

In the example, the initial magnetization was performed on the entire film, but similar multi-pole magnetization can be performed even if it is performed on a part of the film. Also, although a laser was used as the demagnetization method, an electron beam may also be used. . Furthermore, the boundary of one magnetic pole may be made clearer by applying an external magnetic field in the same direction as the magnetization direction of the demagnetizing section.

〔Effect of the invention〕

As described above, according to the present invention, there is no need to change the jig for each magnetic pole width as in the conventional case, and it is possible to easily and accurately perform multi-pole magnetization.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram showing the configuration of the laser oscillator and vacuum chamber used in the embodiment of the present invention, Fig. 2 is an explanatory diagram showing the demagnetizing part of the magnetic film, and Fig. 3 shows the direction of magnetization after demagnetization. It is an explanatory diagram. 1: Film heating device, 2: Magnetic film, 3: Laser beam introduction window, 4: Vacuum chamber, 5: Laser oscillator.

Claims (1)

[Claims] 1. Semi-rigid or rigid Sm-Co formed on a substrate,
Magnetic film such as ferrite is heated to the Kyuri point Tc (℃)
After preheating to a temperature of 0.1 to 0.95Tc, the film is magnetized in the thickness direction, and then part or more of the magnetized part is heated and demagnetized with a laser or electron beam. A multi-pole magnetization method characterized by magnetizing using the magnetic field in areas where there is no magnetic field. 2. The multi-pole magnetization method according to claim 1, characterized in that a magnetic field is applied to the heating demagnetization section in a direction opposite to the direction in which it was initially magnetized.