JPS6329321B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recording and reading data from a perpendicularly magnetized film made of a rare earth-transition metal amorphous alloy.

Conventional normal magnetic recording method, namely γ-
There is a method for writing and reading information in the form of a magnetization pattern using a ring- _shaped magnetic head on a magnetic recording medium that has a magnetic layer made by dispersing a powdered magnetic material mainly composed of Fe ₂ O ₃ , Fe ₃ O 4, etc. in a binder. It is widely used for recording and reproducing audio signals, video signals, measurement signals, and digital signals for computers, but in recent years, magnetic recording media have been used to increase recording density as the amount of information increases. There is a need for a method of recording short wavelength signals.

As a magnetic recording method that enables short-wavelength high-density recording, a perpendicular magnetization recording method has recently been proposed in which information is recorded by magnetizing a magnetic recording layer in a direction perpendicular to the surface of a magnetic recording medium.

The magnetic material used in this perpendicular magnetization recording method is one in which the axis of easy magnetization is oriented in the perpendicular direction (perpendicular to the surface of the magnetic recording medium). Amorphous RE (rare earth)-TM is a magnetic material with an axis of easy magnetization in the perpendicular direction.
(Transition metal) alloy systems are being extensively studied and used. The reason for using this amorphous RE-TM alloy system is that it has high sensitivity due to its low Kyrie temperature (TC) and low compensation temperature (Tcomp).
The advantages include that it can be made into a large area, can be perpendicularly magnetized, has no grain boundaries, allows high-density recording, and is inexpensive. Amorphous RE-TM alloys include, for example, Gd, Tb,
Using Eu, Dy, Ho, Er as TM and Fe, Co,
It is an alloy made by arbitrarily combining these.

In addition to the above-mentioned characteristics, this amorphous RE-TM alloy has the characteristic that coercive force (Hc) and saturation magnetization (Ms) can be changed significantly depending on the composition.

Generally, in order to stably preserve information recorded on a recording medium without erasing it, it is desirable that the coercive force (Hc) of the recording medium be large at room temperature. This is because the greater the coercive force, the greater the magnetic field required to change the recorded content.

Furthermore, when reading recorded information from a medium, the larger the strength of spontaneous magnetization (Ms) of the medium, the better.

In RE-TF alloys, Ms is small at temperatures where Hc is large, and it is disadvantageous to read at temperatures where Hc is large. However, this alloy has a compensation temperature near the temperature where Hc is large, and if the temperature of the medium is shifted up or down from this temperature, Ms increases. That is, Hc
It is advantageous for both storage and readout if the data is stored at a high temperature and read out by shifting the temperature up or down.

The present invention has been made with this point in mind.In practice, it is difficult to cool the medium instantaneously during reading, so the medium is heated to a state where Ms is large during reading. It is characterized by the fact that

That is, the present invention aims to provide a magnetic recording readout method with high storage stability and high S/N ratio using amorphous RE-TM alloy. The device is characterized in that a perpendicularly magnetized film made of an amorphous RE-TM alloy whose composition is selected to have a high saturation magnetization (Ms) at a certain temperature is heated to the temperature of the high saturation magnetization during reading.

According to the present invention, since records are read from the magnetized film at a temperature at which the saturation magnetization value of the material of the magnetized film becomes large, the S/N ratio can be greatly improved, and when stored (usually at room temperature) Since the coercive force (stored in the magnetic disks) is stored in a state where the value of coercive force is large, the storage stability of the records is high, and the recorded contents do not easily change or disappear.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 schematically shows a first example of the recording and reading method according to the invention.

In FIG. 1, reference numeral 1 denotes a tape-shaped or sheet-shaped support 2 and an amorphous RE-
This is a recording medium consisting of a magnetized film 3 made of TM alloy. Amorphous amorphous which forms this magnetized film 3
As shown in Figure 2, the RE-TM alloy is produced at room temperature (20
An amorphous RE-TM alloy is used, which has a large coercive force at temperatures around 50°C and a large magnetic saturation value at higher temperatures (preferably about 50°C or higher). Amorphous RE-TM alloys with such properties include GdFe (Gd ₃ Fe ₅ O ₁₂ ,
Gd ₂₄ Fe ₇₆ ), TbFe (Tb ₂₁ Fe ₇₉ ), DyFe (Dy ₁₇ Fe ₇₉ )
etc.

The magnetic head 4 used in the method of the present invention may be of the ring type used for normal magnetic recording reading, as shown in FIG. In the vicinity of the magnetic recording medium 1, there is a magnetized film 3 of the magnetic recording medium 1.
A light source 5 is disposed to irradiate a heating light beam L onto the portion 1A from which the record is to be read. As this heating light beam L, laser light, infrared rays, etc. can be used. The portion 1A is heated with the light beam L from the light source 5 from room temperature (for example, about 300°K) to a temperature at which the value of saturation magnetization described above is near the peak (about 350°K). head 4
The record written in the magnetized film 3 is read out.

Figure 2 shows the relationship between coercive force (Hc), saturation magnetization (Ms), and temperature for an example of Tb ₂₁ Fe _79. In this case, coercive force (Hc) is The saturation magnetization (Ms) is as high as 5KOe.
Low at 240 Gauss. Therefore, although the storage stability of recording is high, the signal-to-noise ratio during readout is small and high-quality signals cannot be obtained if left as is. If the temperature is raised by about 50 degrees, the coercive force (Hc) will drop to 1 KOe, but the saturation magnetization will rise to 500 Gauss, making readout with a high S/N ratio possible.

FIG. 3 is a schematic diagram showing another example of the recording/reading method of the present invention, and in this example, a roller 10 equipped with a heater inside is used as the heating means. This example is the same as the example described with reference to FIG. 1, except that a roller 10 is used instead of the light source 5, so further explanation will be omitted.

Note that it is necessary to prevent the magnetic head 4 from being heated by the heating means.

As explained above, in the recording readout method of the present invention, since the recording is read in a state where the saturation magnetization of the magnetic material is large, the S/N ratio and sensitivity are improved, and the recorded magnetic material is read out in a state where the coercive force is large. can be stored, so the records will not be lost.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a first example of the recording/reading method of the present invention, and FIG. 2 is an amorphous RE-TM alloy forming a magnetized film of a magnetic recording medium used in the recording/reading method of the present invention. Figure 3 is a graph showing the temperature characteristics of coercive force and saturation magnetization of
FIG. 3 is a schematic diagram showing a second example of the record reading method of the present invention. DESCRIPTION OF SYMBOLS 1... Recording medium, 2... Support body, 3... Magnetized film, 4...
Magnetic head, 5... light source, 10... heating roller.

Claims (1)

[Claims] 1. A perpendicularly magnetized film made of a rare earth-transition metal amorphous alloy that exhibits high coercive force at temperatures around room temperature and high saturation magnetization at temperatures higher than room temperature is used as a magnetic recording layer, and records in the magnetized film are read out during recording and reading. A recording reading method characterized by heating the magnetic part to a temperature at which saturation magnetization is high.