JPS5817505A - Photothermomagnetic track moving method - Google Patents

Abstract

PURPOSE:To perform diverse operation such as information rewriting by moving a track, having an array of pieces of bit information recorded photothermomagnetically, over light irradiation, and erasing and selectively reading the pieces of bit information. CONSTITUTION:A nonreflective coating layer 1c, a reflective film 1d, and a protective 1e are adhered to the thin film obtained by growing a magnetic thin film 1a of garnet on a crystal substrate 1b. This constituted thermomagnetic record reader 1 is fixed to a bias magnetic field generator 2 and applied with a bias magnetic field. Laser light from a light generator 5 is introduced into an optical modulator 6 to form bits on the device 1 through the constitution shown in the figure. Then, the repetitive frequency is set to 100Hz and while the bias magnetic field is unchanged, light irradiation is carried out in the opposite direction to writing. As a result, the bits move to the opposite side to form a new track. For the reading of the bit information, reflected light is introduced into a detector 15 and observed.

Description

DETAILED DESCRIPTION OF THE INVENTION The invention relates to a photothermal magnetic track moving method.
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The present invention relates to a technology that is useful in addition to enabling various operations such as erasing bit information, rewriting information, etc.

Conventional photothermal magnetic storage systems all use large coercive force to retain and stabilize bit information, so it is impossible to move bit information once it has been written due to the large coercive force.・In addition, the present invention has found that the bit information can be stably retained in the 9-character 11JII by using a magnetic material with a sufficiently small coercive force, which is different from the conventional method. A method has been perfected for selectively moving 9-bit information that cannot be captured by technology.

Therefore, the present invention provides a method for selectively moving tracks in which bit information stored photothermally and thermally is arranged by irradiation with light. The anti-adhesive force is sufficiently smaller than the bias magnetic field applied to the bit information recording mechanism, and its W&
It is a small soft magnetic material that has strong uniaxial magnetic anisotropy in the direction perpendicular to the magnetic film and has an axis of easy magnetization in the m-plane, and is a so-called soft magnetic film surface mtm easily magnetized film. ◎ Even in the case of the soft-type art of the trench ninety-seven, if this easily magnetized film is overused as a magnetic recording medium, the diameter of the bit that will be inserted into it will be is essentially determined only by the applied bias magnetic field 4! ! &
The coercive force of the magnetic material used is preferably about 30e or less, more preferably about 30e or less.

Such magnetic *ga, soft magnetic gallium garnet (GGG
It is preferable to grow a crystal such as Y8mCak'eGe-based garnet F on a crystal substrate such as cloth-like gallium garnet such as ) by liquid phase epitaxy method (LPn).

Easy magnetization perpendicular to the surface of the soft magnetic film obtained as described above.
By applying a predetermined tonic bias magnetic field, the gold mine of the gland is magnetized in the same direction as the magnetization direction of the bias stirrer applied perpendicularly to the membrane surface. When this *ia zone number is irradiated with a light pulse, a bit is formed as a cylindrical magnetic domain with magnetization in the opposite direction to the applied bias magnetic field and perpendicular to the film surface. is formed. The bias magnetic field applied when forming this bit is 2 Noaud sulfur fields H2;
and the lapse magnetic field HO. This range obviously varies somewhat depending on the magnetic material used, but an example is the case of the YamCaFeGe garnet mentioned above (
YslrICa)i(FeGe)s01*LPj! 1
14ζ is a leap between 5106 and 750e.

A desired bit is moved from the track where the bits formed in the manner described above are lined up, and a substantially continuous light is emitted while applying a bias magnetic field of m times the difference between the run act magnetic field and the coppice magnetic field. It is irradiated at a predetermined distance from the track, and the bits accompanying the continuous light or the bits to be moved that are approaching due to the temperature gradient formed by the incident light are removed from the track by counterforce.
This is done by jumping to the shrine.

It should be understood that the term "substantially continuous light" used in the present invention includes, in addition to normal continuous light, mechanically intermittent light that does not leave a record even when the light is incident. Therefore, the pulse repetition rate of the beam may be arbitrarily fast compared to the relative speed between the magnetic thin film and the beam. This substantially continuous light must always accompany the bit 1 (II). It is preferable that the intensity is such that the bow 1 is attracted by the temperature gradient formed by the incident light, and the force S allows the bow to be thrown a predetermined distance by the repulsive force without being drawn in. However, even if the intensity of the continuous light is high, the distance from which the light enters the moving truck cars is reduced, which reduces the repulsive force between the bits.

In the present invention, the bias magnetic field for track movement is applied without changing the direction of application of the bias field for recording bit information, so that it is applied along with the substantially continuous incidence of the light. The coming bit has the same direction of sulfidation as the recorded bit.Therefore, one bit has the same direction of sulfidation (t).

From having direction - foot movement #I! When you get close to the target, its ELii force is greater than the ability to absorb the attracted bit, and it can send the bit flying away. This power repellent power bit pole is Oshima, Yang Dai 1
(9) The bit diameter is large enough for the bias magnetic field to be small. Therefore, the light incident for moving the bit information must be within the range of the 2-act magnetic field and the lapse magnetic field, and as much as possible. It is preferable to apply a small bias magnetic field.For example, s (Yl, rotation 8ma, 1cao,
m) (I?e4.cmGeo,es)01g In case of garnet, WJm'''eh is applied by applying an intramedullary bias magnetic field of s 480e and 560C. The force that the p-pit is attracted to by the temperature gradient caused by the substantially continuous light can be expressed by the following equation. CM%Cq: Positive mavd determined by physical switch: Bit moving speed m: Ilization g,: 1ili energy ΔM: Gradient of magnetization picture at both ends of the bit diameter Δ#w: Gradient of domain wall energy at both ends of the bit diameter ζ Here, the temperature coefficient of # is generally negative, and
Since its absolute value is larger than the temperature coefficient of the stock, the direction of movement of the pickle is controlled by the second term on the right side of the above equation, and is the smaller one of #1, that is, the direction of the temperature. Furthermore, as can be seen from the above equation, the drag force (&) needs to be sufficiently small to make the bit disappear into the light or beam.

Therefore, as mentioned above, by adjusting the repulsive force between the bits to become much hotter than the force that attracts the bits due to the temperature gradient caused by the thermomagnetic effect due to the incidence of light, bit information can be obtained in a desired manner. Allows for truck movement.

By the method according to the present invention, desired bit information can be selectively moved from the track, and only the necessary predetermined bit information can be read out and used in combination with the previous bit information. etc. are IJ Noh◎Also,
Depending on the incident position of the substantially continuous light, the desired bit information can be selectively moved to the right or left side of the track, and this movement operation is possible even during the operation), which is extremely convenient in practice. . For example, if d% first continues to inject the continuous light into a predetermined position on the left side of the track to move the bit information to the right side of the track, and then moves the continuous light to a predetermined position on the right side of the track and continues the injection, then can move bit information to the left of the track. 9. If there is bit information in the same vine that does not need to be moved, the bit information can be selectively moved by emitting continuous light at a distance and moving it to a position where it is not affected by the temperature gradient. It also slows down. Refreshingly,
In the method of the present invention, similarly, the bit information can be returned to its original position on the track by injecting continuous light on the outside of the transferred 9-bit information. If the amount of incident light at the incident position of the continuous light is kept constant, the amount of bit movement e can be kept constant. In this case, any bit can be accurately moved in any direction by using a method called two-way servo. In this way, the 9-bit information track that is moved with a constant amount of movement becomes a new friend's track. This is all you need to read out the information you need.

Therefore, the new truck moved in this way also
The original track can also be used to create a headset. Along either track, horizontally placed weak light that does not affect the d bit, even at a wavelength of 488 nm, can be used to absorb light with a weak absorption wavelength. It can be read out by making it incident. In this case, the bit information that was not moved was erased by the new track that was moved and formed, and the 9-bit information that was moved by a% was erased from the original track. . By selectively combining and performing the above-mentioned operations, it is possible to select information and move it by 1 to the OIL, which has the ability to rewrite the information, and write new bit information in the place of the 9-bit information. It also slows down the process, so
It is also possible to record a variety of information on one track, which is useful for preventing ionization.
A wide variety of operations such as selective reading and rewriting of information are possible.

The present invention will be explained below by way of examples.

Example 1 As a sample, fir, (Yl,?I 8m(1,IC!io,t
s ) (Fe4.02 Ge O,9B ) 01z
A thin film of garnet with a thickness of 4.6 ewr was used. Saturation magnetization of this thin film 4gM5== 1420%a Wall resistance 11 Force Hc= CL50e %:1 ps Magnetic field=
62.70e 90 Using this II membrane, form a thermonasal air recording device (1) as shown in Fig. 1. (FeG
e) A solid thin film (1 field) of 6012 garnet etc. is grown to lIc length by liquid phase epitaxial method on a single crystal group 4K (1b) of rare earth gallium garnet to obtain a round thin film, non-reflective =
- A reflector layer (1C) is placed on the opposite side of the crystal substrate, and a reflection j[(14) made of an Al-based Ecum vapor-deposited film with a thickness of 0.3B1g11 and a thickness α5 on the outside thereof. The proverbial protective film made of silicon dioxide (
As shown in %lI2-, the thermomagneto-optical recording projection Mt (1) consisting of a magneto-optical recording device with a magneto-optical structure as shown in FIG. (
In 2), the nine toes are removably attached and fixed, and arranged so that a bias magnetic field is constantly applied. This thermomagneto-optical recording/reading device can be configured to be movable by a motor (3) or the like. In addition, it is also possible to place a bias coil (4) around the device and increase the bias voltage if necessary.〇1it (1) with such a configuration In contrast, the light generation device 5) generates −8<9, for example, the wave height is 484 $nm.
The argon laser is introduced into the light converter (6) to emit 4E9 pulsed light, and the pulsed light is sent to the polarizer (7).
Then, the bit was made incident through the lens (9) through the bar 7 (8). The incident light jliP in this case was 15 mW, pulse power 50μ, repetition frequency line IMg, and bias voltage 510e.

While irradiating pulsed light under the above-mentioned conditions, the device (1)
is moved in one direction at a constant speed to form a track with bits lined up in a straight line with a separation of about 27-.Next, the frequency is set to 100 Hz and the bias magnetic field is repeated 9 times without changing the intensity of the light and the ring. Light was irradiated at a distance of half the diameter of the bit from the track in the opposite direction to the direction in which the device was moved when loading the book without changing the information. As a result, the bits are 10 (Jjd
The pulsed light of g is irradiated and the opposite side is bit I! ! , m
It was found that the irradiation position of the continuous light in the present invention is determined by the rotation detection mechanism a-men attached to the motor (3). The tracking movement is facilitated by moving the motor by 1 m using the movable chassis as by means of a driving gear a provided in conjunction with the moving chassis as.

The head line of the bit information written on this thermomagnetic optical recording/reading device (1), the polarized light from the reflective film (bell) of this device is introduced into the detector, and the light is It is also possible to send p to a photomultiplier tube .mu., and its output to be outputted by an osci scoop a.eta. Among them, when performing memory alignment using transmitted light, the reflective film (1d) is removed from the exposure device (1), and the bias field generating device (2) is used.
That iI! The tm light is linearly polarized, especially due to the Faraday effect, at the periphery of the device rather than at the bottom, and it is only necessary to make it visible by transmitted light.Example 2 Using the same sample and conditions as Example 1, a 9-bit track was performed using WI2. ? The truck was moved in the same way as 111. In this case, the sample moving speed is set to 2? without changing the amount of incident light and the bias value. The track movement situation was improved by using 20 x V-noses for aperture per second. The results are shown in No. 511. In the figure, -
In the right corner of 15, the approaching bit is absorbed by the light and disappears, and in the lower IKjllc of **a, the bit does not follow the light beam and is left behind, causing a tortoise movement. Therefore, the areas where the track of bit information can be moved are the left III area of -15 and 1lli
This is the upper area of iB.

Embodiment 6 A bit track arranged using the same sample and conditions as in Embodiment 1 was moved in the same manner as in Embodiment 1. Incidentally, the incident light amount of the light used for track movement is i 1.3 mW%/(Rousse is 50A11. Bias magnetic field is set to 5606, 1llI!1liII11
The critical light pulse 74uIL#ν (output) at which the bit follows the light beam corresponding to 111B was determined as a function of the sample moving speed Ma (μ weight, Xsha). Show the results to the fourth thief. From Figure 4, it was found that li & field light (Rus frequency ν and sample moving speed 1. It has been shown that the bit cannot be clouded by the light beam if it exceeds a certain value (9.5μ weight in FIG. 184).In addition, in the 4th-, the upper region of il- is within the track movable region.

Example 4 Tracking was performed using the same sample and conditions as used in Example 6. Note that the light expansion pulse used for track movement is 5Ll#s, and the bias lll#
The temperature was set to 560C, the sample was moved with a 29#Il stain, and the critical light pulse frequency ν was changed to determine the amount of sample movement between light pulses Ma/ν (μm) as the incident light amount PO)@number. The results are shown in Figure 185. In FIG. 5, the upper area of the cocoon is the area where the track can be moved.

In the sub-figures to FIG. 5, in the track movable area, as shown in the first embodiment, the following necessary conditions are met at the same time for track movement to be performed. 8. Due to track movement, the reaction force generated between the bit accompanying the incident light beam and other approaching bits is reduced by the m-degree gradient formed by the incident light beam. The force p that attracts the bit is also strong, and the light beam always accompanies the bit is even in the absence of other bits. Even if the light is at the threshold where the light is broken, it is possible to catch the next pulse and attract other bits. In principle, track movement is possible even in the boundary line 1→ region shown by When it is hit, the bit that is attached to the light beam will also be snatched away from the light beam by the reaction and fly out, so it is better not to use the party beam in the area between 9 and 9 when moving the track. It is preferable from a practical standpoint, and it is undesirable to provide a device that allows for less leeway in conditions such as the amount of incident light. Under such conditions on the edge of the boundary line, it is possible that the physical properties of the sample are non-uniform and the expansion operation may be performed at some point, so it is preferable to avoid such conditions.

[Brief explanation of the drawing]

111 - Cross-section showing the thermo-magneto-optical memory display arrangement used in the present invention -, @2 Figure Hiroshi Purutsuta-Hiro showing an outline of an example of a rounded @wax embodying the present invention, and 6th ~ g411
This is a graph showing the characteristics of two-point movement◎ In addition, in the symbols used in the drawings, (,1)'
?・・・・・・・・・Magneto-optical recording readout stand (1
m) ...... Magnetic thin film (1b) ---
・・・Crystal substrate (2) ・・・・・・・・・Bias Kōkai Kyoei device collection υ・・・・・・・One rotation detection mechanism I・・・・・・
・・・・・・・・・It is a mobile chassis ◎ Agent Souvenir Tenyokozai Repair (Order) Procedures Amendment (Method) December 2, 1975 Mr. Commissioner of the Japan Patent Office 1, Case Indication 1988 Patent Application No. No. 114845

Claims (1)

[Claims] The bias magnetic field applied by the coercive magnetic force of the magnetic bell 1141 The direction of the bias field applied to a magnetic thin film made of a sufficiently small magnetic material and the direction of the magnetization of the magnetic field. In conjunction with the Cottbus magnetic field, substantially continuous light is directed a predetermined distance 4-4 from the bit information track.
11. A photothermal magnetic track $11 method characterized in that the ridges are removed from the track by the repulsive force with the bit that accompanies the light irradiation.