JPH02235231A - Magneto-optical recording medium, magneto-optical recording method, magneto-optical erasing method, and magneto-optical recording and reproducing device - Google Patents

Abstract

PURPOSE:To thin a device by laminating two magnetic layers respectively having a specific Curie point and room temperature coercive force, setting up the magnetization of both the magnetic layers in the stable direction of magnetization and using one of the magnetic layer as an auxiliary magnetic field forming layer and the other as a recording layer. CONSTITUTION:The recording layer 33 has a low Curie point and high coercive force at a room temperature and the auxiliary magnetic field forming layer 30 has a Curie point higher than that of the layer 33 and low coercive force at the room temperature. When magnetic field intensity Hb for inverting only the magnetization of the layer 30 by a bias magnetic field head 7 in an erasing state e.g. is impressed in the shown arrow direction, only the magnetization of the layer 30 is inverted and a recordably state is set up. When the surface of the layer 33 is irradiated with a laser beam modulated by an information signal and the laser beam is condensed thereon, only the laser 33 reaches the Curie point, and in a process reducing the temperature from the Curie point, the direction of the magnetization is reversed from that of the erasing state and recording can be executed. Consequently, it becomes unnecessary to arrange the bias magnetic field head 7 oppositely to the optical head 3 and the device can be thinned.

Description

[Detailed description of the invention]

[Field of Industrial Application] The present invention relates to a magneto-optical recording medium employing a magneto-optical recording method, a method for recording information on the medium, a method for erasing information, and a magneto-optical recording and reproducing apparatus.

[Conventional technology]

Conventionally, magneto-optical. Magneto-optical recording/erasing devices that perform recording and playback using air generally have the configuration shown in Figure 6. In the figure, a magneto-optical disk 1 is a glass substrate 10 or the like coated with perpendicular magnetism 2, and an optical head 3 and a bias magnetic field head 7 are arranged across the magneto-optical disk 1. There is. Here, bias magnetic field head 7
is an electromagnet formed by passing a current through a coil 8, and by controlling the direction of the current flowing through the coil 8 by a magnetic field drive circuit 9, the direction of the magnetic field generated from the bias magnetic field head 7 can be switched. There is.
At this time, a constant magnetic field strength is generated during recording or erasing, respectively. Further, the optical head 3 is adapted to move in the radial direction of the magneto-optical disk l, and is arranged opposite to the bias magnetic field head 7 with respect to the magneto-optical disk l. The optical head 3 focuses laser light emitted from a built-in semiconductor laser onto the perpendicularly magnetized film 2.
The optical modulation circuit 4 is operated by the information signal input from the terminal 5 to drive the optical head 3. Also, magneto-optical disk 1
is rotated by a spindle motor 6. In the above configuration, when a recording signal is input as shown in FIG.
, then the laser beam modulated by the recording signal is irradiated onto the perpendicularly magnetized film 2, the irradiated part of the perpendicularly magnetized film 2 reaches a temperature above the Chieri point, and the applied bias magnetic field causes the part of the perpendicularly magnetized film 2 to become heated. The magnetization is reversed and a recorded bit is formed. [Problems to be Solved by the Invention] However, in the conventional example described above, it is necessary to arrange the bias magnetic field head 7 at a position facing the optical head 3 with respect to the magneto-optical disk l, which makes the magneto-optical recording/reproducing/erasing device thin. The disadvantage was that it could prevent oxidation. [Means for Solving the Problems] In view of the above-mentioned drawbacks, an object of the present invention is to provide a magneto-optical recording medium, a magneto-optical recording method, a magneto-optical erasing method, and a magneto-optical recording method that can reduce the thickness of a magneto-optical recording/reproducing/erasing device. We may provide equipment. In order to achieve the above objectives, first of all, we need a low Curie point TL and a high holding power H. at room temperature. a first magnetic layer having a relatively high Curie point TH compared to this magnetic layer;
and a second magnetic layer having a low coercive force HL at room temperature, the magnetization of both magnetic layers is set in a stable magnetization direction (parallel or antiparallel may be used), and the second magnetic layer is auxiliary. A magneto-optical recording medium is provided, characterized in that the first magnetic layer is used as a magnetic field forming layer and as a recording layer. Next, using the magneto-optical recording medium, after magnetizing only the direction of magnetization of the auxiliary magnetic field forming layer in the opposite direction at room temperature using an external magnetic field applying means, the recording layer is exposed to light whose intensity is modulated by the recording signal. A magneto-optical recording method for recording information is provided by scanning with a beam and magnetizing the recording layer in a direction that is energetically stable with respect to the opposite direction of magnetization. Furthermore, in the state recorded in the above procedure, after the magnetization direction of the auxiliary magnetic field forming layer is magnetized in the original direction at room temperature by an external magnetic field applying means, the recording layer is scanned with a continuous light beam to record the original. Provided is a magneto-optical erasing method for erasing information by magnetizing all of the recording layer in a direction that is energetically stable with respect to the direction of magnetization. Finally, there is provided a magneto-optical recording and reproducing apparatus using the magneto-optical recording medium according to the present invention, wherein the external magnetic field applying means and the optical head for emitting the light beam are both provided on one side of the recording medium. provide. The above objects are achieved by the above four inventions. [Function] According to the present invention, the perpendicular magnetization of the magneto-optical disk is made into a multilayer film of two or more layers, and the direction of magnetization of one layer is determined by the bias magnetic field applied by the bias magnetic field head, and the direction of magnetization of the other layers is determined by the bias magnetic field applied by the bias magnetic field head. If a laser beam is applied to a region that is not affected by a magnetic field and a bias magnetic field is applied, the layer whose magnetization is determined by the bias magnetic field will be magnetized in a direction that is energetically stable. By using a perpendicular magnetization multilayer film, there is no need to place the bias magnetic field head opposite the optical head, and the bias magnetic field head can be placed in the same plane as the optical head. ) It is possible to make the playback device thinner. [Example] Hereinafter, a magneto-optical recording medium, a magneto-optical recording method according to the present invention,
The magneto-optical erasing method and magneto-optical recording/reproducing device will be explained in detail based on specific examples. FIG. 1 is an embodiment that best represents the features of the magneto-optical recording and reproducing apparatus of the present invention. In the same figure, 1 is a multilayer perpendicularly magnetized film 2 placed on a glass substrate 1.
This is a magneto-optical disk coated with 0. magneto-optical disk 1
is rotated by a spindle motor 6 around a central axis of 0-0°. Reference numeral 3 designates an optical head basically consisting of a semiconductor laser. The optical head 3 is driven by an optical modulation circuit 4, and the optical modulation circuit 4 is driven by an information signal inputted from a terminal 5. The optical head 3 is configured to always focus laser light emitted from a semiconductor laser onto the multilayer perpendicular magnetization layer 2 of the magneto-optical disk 1.
Further, the optical head 3 is configured to be able to move in the radial direction of the magneto-optical disk 1. 7 is optical head 3
This is a bias magnetic field head placed in the same plane as the . The bias magnetic field head 7 is horizontally configured to generate a magnetic field by a magnetic field drive circuit 9. This magnetic field head 7 is configured to apply a constant bias magnetic field to the entire radial area of the magneto-optical disk 1. In the configuration described above, FIG. 2 shows the principle of recording operation, and FIG. 3 shows the principle of erasing operation. In FIG. 2, numeral 2 denotes a multilayer perpendicular magnetization film of the magneto-optical disk 1, which here has a two-layer structure. Of these, 30
33 is a second magnetic layer serving as an auxiliary magnetic field forming layer (hereinafter referred to as an auxiliary layer), and 33 is a first magnetic layer serving as a recording layer. The first magnetic layer 33 has a low Curie point TL and a high coercive force H at room temperature. The second magnetic layer 30 has a relatively high Curie point TH and a low coercive force HL at room temperature compared to the first magnetic layer 33. An example of these characteristics is shown in Figures 4 and 5, with holding force on the vertical axis and temperature on the horizontal axis. In both figures, 40 is the characteristic curve of the first magnetic layer 33, and 44 is the characteristic curve of the second magnetic layer 30.
In FIG. 4, the characteristic curve of the second magnetic layer 30! 144 has a compensation point for the Curie point, but in the present invention, not only the configuration shown in FIG. 4 but also the configuration shown in FIG. 5 can be adopted. Referring again to FIG. 2, the arrows within each film indicate the direction of magnetization of each layer. The auxiliary layer 30 is exposed to a bias magnetic field H. On the other hand, the characteristics and bias magnetic field HI of the recording layer 33 are determined so as not to be affected in any way. In addition, the intensity of the laser beam irradiated to the recording layer 33 is such that only the recording layer 33 has a Curie point T.
Unlike L, an intensity that does not reach the Curie point TH of the auxiliary layer 30 is selected. In the configuration having the above characteristics, the state (a) is a two-layer perpendicular magnetization film that is energetically stable, and this is set as the erased state. In this state, the bias magnetic field head 7 is used to invert only the magnetization of the auxiliary layer 30 with a magnetic field strength H. (
4 and 5) in the direction shown in the figures, the magnetization of only the auxiliary layer 30 is reversed, resulting in a magnetization state as shown in (b). This state is the recordable state. A laser beam modulated by an information signal (see FIGS. 4 and 5 for the strong optical power range) is irradiated and focused onto the recording layer 33 of the double-layer film perpendicularly magnetized in a recordable state. As explained above, only the perpendicularly magnetized film of the recording layer 33 reaches the key point. As the temperature of the perpendicularly magnetized film of the recording layer 33 decreases from the Curie point, the direction of m-ization of the perpendicularly magnetized film of the recording layer 33 becomes energetically stable with respect to the magnetization direction of the auxiliary layer 30 due to exchange coupling force. The magnetization will be directed in the direction. The direction of this magnetization is opposite to the direction of magnetization of the recording layer 33 in the erased state (a), and as a result, recording can be performed. Figure 3 shows the principle of erasure operation. Figure 3(a)
shows the recorded state corresponding to Fig. 2(c). A bias magnetic field intensity Hb is applied to the perpendicular magnetization of the two-layer film in this recorded state by a bias magnetic field head 7 in a direction opposite to that during recording, as shown in the figure. Bias magnetic field H. is applied,
The direction of magnetization of the recording layer 33, which has a high coercive force, does not change, and only the magnetization of the auxiliary layer 30 is oriented in the direction to which the bias magnetic field H is applied. Let this state be the erasable state. In the erasable state, the recorded information recorded on the recording layer 33 remains unchanged (FIG. 3(b)). 2 in this erasable state
By continuously irradiating the perpendicular magnetization of the eyebrow membrane with laser light at a laser light intensity such that only the recording layer 33 reaches the Curie point, the perpendicular magnetization film of the recording layer 33 reaches the Curie point and the temperature decreases. In the process of decreasing, the direction of magnetization of the recording layer 33 is determined by the exchange coupling force in a direction that is energetically stable with respect to the direction of magnetization of the auxiliary layer 30, as in the case of recording. Therefore, after the direction of magnetization is determined, the data is erased in the same state as shown in FIG. 2(a) (FIG. 3(c)). The present invention is not limited to the embodiments described above, and various embodiments are possible. For example, the auxiliary layer 30 and the recording layer 33 in FIG.
The stable direction of magnetization of can be parallel or antiparallel. Further, although FIG. 1 shows a configuration in which the optical head 3 and the bias magnetic field head 7 are separated in distance, a configuration in which the optical head 3 and the bias magnetic field head 7 are disposed immediately in front of the optical head 3 may also be used. [Effects of the Invention] As explained above, according to the recording medium, recording method, erasing method, and recording/reproducing apparatus of the present invention, it is no longer necessary to place the bias magnetic field head opposite to the optical head, and the bias magnetic field head can be It can be placed in the same plane as the optical head, which has the effect of making the magneto-optical recording/reproducing/erasing device thinner. Further, according to the present invention, there is an effect that less laser power is required compared to the conventional configuration.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an embodiment of the magneto-optical recording/erasing device of the present invention, FIG. 2 is a diagram showing the recording process of FIG. 1,
FIG. 3 is a diagram showing the erasing process of FIG. 1, FIGS. 4 and 5 are diagrams showing the characteristics of the auxiliary layer and the recording layer, respectively, and FIG. 6 is a block diagram of a conventional magneto-optical recording/reproducing/erasing device. Figure 7 is a diagram showing the recording process of Figure 6. l: magneto-optical disk, 2: perpendicular magnetization film, 3o: auxiliary layer, 33 second recording layer, 3: optical head, 4: optical modulation circuit, 5:
Input terminal, 6: spindle motor, 7: bias magnetic field head, 8: coil, 9: magnetic field drive circuit, 10: glass substrate. Figure 1 O Agent Patent attorney Minoru Yamashita Hei 0--Category letter of entry《0》:l4 information. Tortoise Figure 2 (b) Kototsuichik;rJ and Shoben (C) tL Lesson Choice 1 KashiL Figure 7. !Attendance diagram

Claims (4)

[Claims] (1) A first magnetic layer that has a low Curie point T_L and a high coercive force H_H at room temperature, and a second magnetic layer that has a relatively high Curie point T_H and a low coercive force H_L at room temperature compared to this magnetic layer. are laminated at least, the magnetization of both magnetic layers is set in a stable magnetization direction, the second magnetic layer is used as an auxiliary magnetic field forming layer, and the first magnetic layer is used as a recording layer. magneto-optical recording medium. (2) Using the magneto-optical recording medium according to claim 1, after magnetizing only the magnetization direction of the auxiliary magnetic field forming layer in the opposite direction at room temperature by an external magnetic field applying means, the recording layer is intensified with a recording signal. A magneto-optical recording method for recording information by scanning with a modulated light beam and magnetizing the recording layer in a direction that is energetically stable with respect to the opposite direction of magnetization. (3) In the state recorded by the procedure set forth in claim 2,
After the direction of magnetization of the auxiliary magnetic field forming layer is magnetized in the original direction at room temperature by an external magnetic field applying means, the recording layer is scanned with a continuous light beam, and the direction of magnetization in the original direction is changed energetically. A magneto-optical erasing method that erases information by magnetizing all of the recording layer in a stable direction. (4) Magneto-optical recording using the magneto-optical recording medium according to claim 1, wherein the external magnetic field applying means and the optical head for emitting the light beam are both provided on one side of the recording medium. playback device.