JPH02189751A - Magneto-optical recorder - Google Patents

Abstract

PURPOSE:To attain high speed access by using a specific magneto-optical recording medium provided at least with 2 layers of magnetic films and providing a light beam spot irradiating means to a slider floated with air on the medium together with a perpendicular magnetic recording head. CONSTITUTION:A recording auxiliary layer 18 increases its coercive force according to temperature rise from a room temperature and a recording layer 19 decreases its coercive force according to temperature rise from a room temperature and a recording layer 19 and a perpendicular magnetic recording head 13 and a light beam spot radiation means 14 are provided in a slider floated with the force of air with relative product/sum to the direction of an information track. After an information magnetic domain is formed in the recording auxiliary layer 18 by a modulated magnetic field from the perpendicular magnetic recording head 13, the light beam spot irradiating means 14 heats the recording layer 19 up to the Curie temperature to erase the information in the recording layer 19 and the information magnetic domain of the recording auxiliary layer 18 is transferred magnetically to the recording layer by utilizing the exchange bond effect. Thus, the structure of large sized and heavy weight optical head is not required and high speed access is attained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magneto-optical recording device that records information on a magneto-optical recording medium through the interaction of light and magnetism.

(Prior Art) Magneto-optical disks as magneto-optical recording media are attracting attention because of their large distribution capacity and their ability to be erased and rewritten, but in order to increase the data transfer speed, An override method is used in magneto-optical recording devices. This over-write method involves applying a constant external magnetic field while modulating binary radar waves corresponding to recording and erasing onto the magneto-optical recording medium according to the recorded information. By applying an external magnetic field modulated according to the recorded information to the magneto-optical recording medium without irradiating it with a constant laser beam, A magnetic field modulation method is known in which magnetic domains are formed by reversing the magnetization of a recording layer.

In particular, the latter magnetic field modulation method has a configuration as shown in FIG. Here, the magneto-optical recording medium has a magnetic thin film 4 on a disk substrate 5, and a protective coat 3 is provided on its surface to improve acid resistance and durability. A perpendicular magnetic recording head 2 is provided on a slider 1 that floats in the air by rotating the magneto-optical recording medium, and a light beam spot from a semiconductor radar is transmitted through the disk substrate 5 and irradiates the magnetic thin film 4. A magnetic recording device is used. In this device, the current flowing through the perpendicular magnetic recording head 2 is modulated according to the information to be recorded, and as a result, the external magnetic field that affects the magnetic thin film 4 is changed, and the temperature of the magnetic thin film 4 is changed by the light beam spurt. This causes the magnetic domain 7 to rise in response to the external magnetic field. In this case, the above-mentioned light beam spot requires that the light beam from the radar is focused by the objective lens 6 of the optical head and irradiated toward the disk substrate 5. Therefore, the objective lens 6 must be focused on the information track to be recorded. It is necessary to accurately control the focus and further control the tracking.

(Problem to be Solved by the Invention) However, in such a magnetic field modulation method, it is necessary to accurately focus the objective lens 6 on the information track and also perform tracking control, and this control mechanism requires an optical head. It becomes heavy and sacred. This becomes a bottleneck in that the speed of access to information cannot be improved. Furthermore, the recorded magnetic domains are formed in the shape of arrow feathers, making it difficult to record the mark length.

On the other hand, since the former optical modulation method requires a large and heavy optical head, it cannot improve the access speed like the above-mentioned magnetic field modulation method, and it also has the disadvantage of causing unerased data. Furthermore, three levels of light/nine power control are required depending on the recording, erasing, and reproducing states, making control cumbersome.

General optical information recording/reproducing device (other than magneto-optical distribution method)
For example, as disclosed in Japanese Patent Application Laid-open No. 63-100631, a high-speed access optical head has been proposed. This optical head cannot be used as it is as an optical head for a light beam spot in a magneto-optical recording device.

(Object of the Invention) The present invention has been made based on the above-mentioned circumstances, and focuses on the fact that the slider has a substantially constant air levitation on the upper surface of the magneto-optical recording medium. The present invention aims to provide a magneto-optical recording device that can increase the speed of accessing information and accurately record mark lengths.

(Means for Solving the Problems) Therefore, in the present invention, information is provided in a magneto-optical recording medium having a magnetic thin film including at least two layers, a recording auxiliary layer and a recording layer, which are provided close to each other. In a magneto-optical recording device that reverses the magnetization of a recording layer and forms a magnetic domain by applying an external magnetic field modulated according to recorded information while irradiating a light beam spot with a constant intensity in the direction of a track, the recording auxiliary layer is The coercive force increases as the temperature rises from room temperature, and the coercive force of the recording layer decreases as the temperature rises from room temperature. The floating slider is provided with a perpendicular magnetic recording head for applying an external magnetic field to the recording medium and a light beam spot irradiation means for raising the temperature. The coercive forces of the recording auxiliary layer and the recording layer are set between each other, and the light beam switch irradiation means sets the temperature rise in the magnetic thin film to be higher than the Chierly point temperature of the recording layer.

(Function) Therefore, after forming an information magnetic domain array in the recording auxiliary layer by the modulated magnetic field from the perpendicular magnetic recording head, by heating the recording layer to the Curie point temperature with the light beam beam irradiation means, Override recording is achieved by erasing the information in the recording layer and magnetically transferring the information magnetic domain array in the recording auxiliary layer to the recording layer using the exchange coupling effect during the cooling process at room temperature. Since the light beam spot irradiation means is mounted on the slider, autofocus control becomes unnecessary. Therefore, there is no need for a conventional heavy and large optical head structure, and high-speed access is possible. In addition, since the information magnetic domain is formed in the recording auxiliary layer using a perpendicular magnetic recording head and then transferred to the distribution layer using a light beam, the information magnetic domain is accurate and the magnetic domain when transferred to the recording layer is The edges are also clean, making it suitable for recording mark lengths.

(Example) Hereinafter, an example of the present invention will be specifically described with reference to the drawings. In FIG. 1, reference numeral 1o denotes a magneto-optical recording medium, and a slider 12 is disposed above the magneto-optical recording medium 1o, supported by a plate-shaped spring member 11. The spring member 11 is movable in the track access direction B by connecting its base side to a drive mechanism (not shown). The slider 12 is
As shown in detail in FIG. 2, this is the same as the one used in a wintier-type magnetic recording device called a "bar disk," but the one according to the present invention has a It is equipped with a perpendicular magnetic recording head 13 and a light emitter 14 as a light beam spot irradiation means. The perpendicular magnetic recording head 13 generates a magnetic field by a current applied to the signal line 15. Further, the light emitter 14 is a semiconductor radar whose bottom surface is a light emitting end, and the signal line 16
It emits light when a current is applied to it. This signal line 15.1
6 are grouped together as the signal line 9 in Fig. 1 and connected to an external power supply (
(not shown).

FIG. 3 shows a cross section of the slider along the C-C' stripe line in FIG. 2, and also shows a cross section of the magneto-optical recording medium 10 (for example, a magneto-optical disk). In this figure, the same components as in FIGS. 1 and 2 are given the same reference numerals.

The magneto-optical recording medium 10 includes a recording auxiliary layer 18 on a substrate 17,
The two layers of the recording layer 19 constitute a magnetic thin film, on which a protective layer 2o of TERRA silicon is provided for the purpose of preventing oxidation and improving moisture resistance. A protective film 21 made of transparent resin is provided on the top of the protective film 21 to prevent dust and scratches.

When the magneto-optical recording medium 1o is rotated by a driver at 180 rpm or 3600 rpm, the slider 12 is floated by the air flow generated by the relative movement during this rotation. Then, at a distance (h) from the surface of the magneto-optical recording medium 10, it is kept roughly constant. The principle of this mechanism is the same as that of the magnetic head in the conventional Wintier-type magnetic recording apparatus. In this embodiment, a magnetic field 22 from a perpendicular magnetic recording head 13 provided in the slider 12 and a light beam spot 23 from a light emitter 14 act on the magneto-optical recording medium 1o, and magneto-optical recording is performed. Information is recorded on the medium 10. In addition,
In this case, the flying height (h) of the slider 12 is determined by the number of rotations of the magneto-optical recording medium 10, the shape of the slider 12, and the weight (
Although it is determined by various parameters such as the weight of the perpendicular magnetic recording head 13 and the light emitter 140) and the spring strength of the spring member 11, in practice, it is usually about 1 μm. Further, the thickness of the protective film 21 is about several μm,
The thickness of the protective layer 20 is approximately 0.1 μm. Therefore, from the recording layer 19 to the perpendicular magnetic recording head 13, the light emitting device 4
The distance to the lower end surface of the substrate should be at most 10 μm or less, preferably within a range of several μm.

FIG. 4 is for explaining the recording principle of the present invention, in which the magneto-optical recording medium 10 is in the form of a magneto-optical disk,
Track 2 with spikele-like or concentric structure
Information is recorded on 4.

The period Wtr between adjacent tracks is about 1 to 2 μm. Note that although a group 25 is shown between each track in the figure, this is not related to the essence of the present invention. Then, magnetic domains 26 are recorded in the recording auxiliary layer 18 in the optical disk layer by the magnetic field from the perpendicular magnetic recording head. This recording magnetic domain is a characteristic of perpendicular magnetic recording, and has a width λMG
is very small and can be 1 μm or less, but on the other hand, for manufacturing reasons of the perpendicular magnetic recording head, the length LMG in the direction perpendicular to the track has a larger width than this, for example, about 10 μm. Therefore, the magnetic domains 26 recorded in the recording auxiliary layer 18 by the perpendicular magnetic recording head 13 have a very high density in the direction parallel to the track and can make λMG small, but in the direction orthogonal to this, they become LMG, and a plurality of It will span the information track. The role of the light beam spot 23 is to limit the information recorded on the recording auxiliary layer over several tracks to one track. The spot size D of the light beam spot 23 becomes approximately one track width or slightly narrower due to the wedge-shaped waveguide structure provided at the exit end of the semiconductor radar.

Next, the function of this light beam spot will be explained using FIGS. 5 and 6. In the multilayer film of the magneto-optical disk, the magnetic properties of the recording auxiliary layer 18 and the recording layer 19, which are involved in information recording, are as shown in FIG. In the figure, the horizontal axis shows temperature and the vertical axis shows coercive force. That is, the recording auxiliary layer has a small coercive force at room temperature TR00M and is made of a magnetic material with a large chirality, and the recording layer 19 has a large coercive force at room temperature and a low Chierly point. Therefore, as shown in FIG. 5(A), if an external magnetic field of magnetic force H is generated from the perpendicular magnetic recording head at room temperature, H, (H(
H! 1, the coercive force of the recording auxiliary layer is canceled and the magnetic field applied from the perpendicular magnetic recording head is recorded in the recording auxiliary layer. This magnetic domain/arm turn has the shape shown by reference numeral 26 in FIG. 4 above. After that, as shown in FIG. 5), the light beam spot 23 is guided from the light emitter 14 onto the recording layer 19, and when the temperature is raised thereto, for example, to the Chierly point TRC, the storage layer in the recording layer is heated. Although the magnetic force is zero, the Chierly point of one recording auxiliary layer 18 is higher than this, so there is sufficient coercive force. Therefore, when the recording layer 19 that has been heated to the TRC cools down (the position of the light beam spot moves away from the corresponding area as the magneto-optical disk rotates), the exchange coupling occurs due to the influence of the magnetic field of the recording auxiliary layer. Depending on whether the recording layer is oriented according to the direction of the magnetic field in the recording auxiliary layer, for example, whether the recording auxiliary layer is facing upward or downward, magnetization occurs in the recording layer in a downward or upward direction (in the case of opposite magnetization). kept at room temperature. Therefore, the magnetic domain of the recording auxiliary layer is transferred only to the portion of the recording layer that is irradiated with the light beam spot. In this case, if the size of the light beam spot is set to be smaller than or equal to the track width size, 1
Information will be recorded only within the track. Information recorded in this manner can maintain a stable recording state without being affected by external magnetic fields because the recording layer has sufficient coercive force at room temperature.

Note that the distance between the perpendicular magnetic recording head 13 and the light emitter 140 is such that the magnetic domain shape recorded by the magnetic field from the perpendicular magnetic recording head is not affected by the heat distribution of the light beam spot. It is desirable because it allows recording with small external magnetic field modulation without increasing the coercive force of the layer, and because it allows accurate recording of magnetic domains by a perpendicular magnetic recording head, making it suitable for high-density recording. Specifically, the specific heat of the magnetic thin film constituting the magnetic layer, the rotation speed of the magneto-optical recording medium, the nozzle of the optical beam, etc.
It is sufficient if the distance is about m or more.

FIG. 7 shows another embodiment of the invention, in which:
Components having the same functions as those in the previous embodiment are denoted by the same reference numerals. In this embodiment, a magneto-optical head is shown which can not only record information but also reproduce information. Here, the structure of the magnetic film of the magneto-optical recording medium is reversed from that of the previous embodiment.

This is because, as shown in Figure 6, the recording auxiliary layer has a high Chieley point temperature, and a magnetic film with a higher Chieley point temperature usually has a thicker Kerr rotation angle, making use of the Kerr effect. This is because it is suitable for reproducing recorded information.

In this embodiment, a perpendicular magnetic recording head 1 for magnetic field modulation is used.
3 and the optical fiber 27 for generating a heating spot perform the same functions as the perpendicular magnetic recording head and the light emitter in the previous embodiment. Here, the optical fiber 27 functions to guide light from a semiconductor radar (not shown) and emit a light beam from the exit end of the fiber processed into a lens shape, thereby forming a light beam spot on the recording auxiliary layer. . The heat distribution caused by this light beam spot is transmitted to the recording layer, and as in the previous embodiment, the information magnetic domain recorded in the recording auxiliary layer is transferred to the recording layer. The optical fiber 28 projects a light beam spot for reproducing recorded information, and is a polarization preserving single mode optical fiber for receiving reflected light from a magneto-optical recording medium. This optical fiber 2
Similarly to the optical fiber 27, the exit end of the optical fiber 8 is also processed into a lens shape. Optical fiber 28 is connected to slider 12
Like the signal line 15, it is guided from the spring member 11 to the fixed optical system provided in the fixed part of the optical information recording/reproducing device.

FIG. 8 schematically shows the fixed optical system. Here, the P-polarized light beam from the semiconductor radar 33 is shaped by a collimator lens e32 and a beam shaping prism 31, passes through a polarized beam smitter 30, and is directed to an objective lens 29. The light is focused and coupled to the optical fiber 28'. The preserved polarization plane direction of the optical fiber and the vibration plane of P-polarized light match. The reflected light from the magneto-optical recording medium returns containing the 6s polarization component due to the Kerr effect, but is converted into parallel light by the objective lens 29, and the psS polarization component is 100% and the ps polarization component is 100% by the polarization beam splitter 3o. Approximately 50% of the light is reflected and guided to the second polarizing beam splitter 34. The second polarizing beam splitter 34 also has a characteristic that, like the polarizing beam splitter 30 described earlier, 100% of the S-polarized light component is reflected and 50% of the P-polarized light component is reflected. The plane of polarization of the light beam is rotated by a half-wave plate 35. The third polarization beam sinter 37 has the characteristics of 5 (l11 light reflectance is 100% and P polarization reflectance is 100%,
It functions as an analyzer. Therefore, by taking the differential output of photodetectors 38 and 39, a magneto-optical information signal can be reproduced. At this time, the 1/2 wavelength plate 35 is rotated and adjusted so that the maximum signal amplitude is obtained.

In the above embodiment, the magnetic film is divided into two layers: the recording layer and the recording auxiliary layer.
Although the magnetic film has a two-layer structure, the structure of the magnetic film is not limited to these two layers. For example, Figure 9 (&) or C
A configuration as shown in b) may also be used.

FIG. 9(c) shows the temperature-coercive force characteristics in these examples.

In FIG. 9(&), an exchange force adjusting layer 40 is arranged between the recording auxiliary layer 18 and the recording layer 19 in the magneto-optical recording medium of the above-described embodiment, and a protective layer 20 is further provided in the lower layer. ing. The coercive force H83 of the adjustment layer 40 and the key point temperature Tc5 have characteristics as shown in FIG. 9(c). This layer 40 is magnetized in the in-plane direction at room temperature,
When the temperature rises, the recording auxiliary layer 18 has the same perpendicular magnetization direction as the magnetization direction, which acts to weaken the exchange coupling force between the recording auxiliary layer 18 and the recording layer 19 at room temperature. The magnetic force at the time can be lowered to the Hc side.

In FIG. 9(a), a reproducing layer 41 is further provided in the embodiment of FIG. 9(&) described above. The Kerr rotation angle due to the Kerr effect during reproduction is larger in a magnetic layer with a higher Chieley point temperature. Considering this point, the coercive force H0 of the reproducing layer 41 is
4 and the Chieri point temperature To4 are selected to have characteristics as shown in the curves in FIG. 9 (,).

During reproduction, this reproducing layer 41 exhibits perpendicular magnetization corresponding to the magnetic domain of the recording layer 19 due to the exchange coupling force with the recording layer 19. Since most of the reproduction light is reflected on the surface of the reproduction layer 41, the Kerr rotation angle is larger than that in reflection reproduction on the recording layer 19, so reproduction can be achieved with high quality signals.

(Effects of the Invention) The present invention has been described in detail above, and when recording is performed using a magneto-optical recording medium having at least two layers of magnetic films having different characteristics, air floating is carried out on the magneto-optical recording medium. By providing a means for irradiating a light beam spot on the slider in parallel with the perpendicular magnetic recording head, perpendicular magnetization is formed in a desired track by the temperature rise caused by the light beam spot within the magnetic domain formed by the perpendicular magnetic recording head. , there is no need for autofocus control, there is no need for the heavy and large optical head of the conventional method, and high-speed access is possible. In addition, recording can be realized in an override format, and the shape of the recording magnetic domain is almost square, allowing for clean etching and less erasure, making it suitable for mark length recording and enabling even higher density recording. Become.

[Brief explanation of the drawing]

Fig. 1 is a perspective view of a slider portion showing an embodiment of the present invention, Fig. 2 is an enlarged perspective view of the main part, and Fig. 3 is a schematic side view showing the relative position of the slider and magneto-optical recording medium. Figure 4 is a schematic view from the same plane, Figure 5 (a), (b)
is a schematic diagram showing the state of magneto-optical recording, FIG. 6 is a temperature-coercive force characteristic diagram of the recording layer and recording auxiliary layer in the magnetic film, and FIG. 7 is a schematic diagram from the side showing another embodiment. Figure 8 is a diagram showing the optical system related to the embodiment of Figure 7, and Figure 9 (a
), (b) is a schematic diagram of a cross section of a magneto-optical recording medium with a special layer added, No. 910...Magneto-optical recording medium, No. 11...
- Spring member, 12... Slider, 13... Perpendicular magnetic recording head, 14... Light emitter, 17... Base, 18...
...recording auxiliary layer, 19...recording layer, 20...
protective layer. 1st rI! J Agent Patent Attorney Jo Taira Yamashita Figure 2 Figure 4 Figure 6 Figure 6

Claims (1)

[Claims] A magneto-optical recording medium having a magnetic thin film comprising at least two layers, a recording auxiliary layer and a recording layer, which are provided close to each other, is irradiated with a constant light beam spot in the direction of the information track, while recording information. In a magneto-optical recording device that reverses the magnetization of the recording layer and forms magnetic domains by applying an external magnetic field modulated according to The coercive force is reduced as the temperature rises from room temperature, and a perpendicular magnetic recording head for applying an external magnetic field to the recording medium is attached to a slider that floats in the air by relative movement with respect to the direction of the information track, and for temperature rise. The perpendicular magnetic recording head sets the maximum magnetic force in the magnetic thin film between the respective coercive forces of the recording auxiliary layer and the recording layer, and the light beam spot irradiation means sets the maximum magnetic force in the magnetic thin film between the coercive forces of the recording auxiliary layer and the recording layer. A magneto-optical recording device characterized in that the temperature increase in the thin film is set to be higher than the Curie point temperature of the recording layer.